Abstract:
A method, system and computer program product that allows a System Image within a multiple System Image Virtual Server to maintain isolation from the other system images while directly exposing a portion, or all, of its associated System Memory to a shared PCI Adapter without the need for each I/O operation to be analyzed and verified by a component trusted by the LPAR manager.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to commonly assigned and co-pending U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040179US1) entitled “Virtualized I/O Adapter for a Multi-Processor Data Processing System”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040180US1) entitled “Virtualized Fibre Channel Adapter for a Multi-Processor Data Processing System”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040181US1) entitled “Interrupt Mechanism on an IO Adapter That Supports Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040182US1) entitled “System and Method for Modification of Virtual Adapter Resources in a Logically Partitioned Data Processing System”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040183US1) entitled “Method, System, and Computer Program Product for Virtual Adapter Destruction on a Physical Adapter that Supports Virtual Adapters”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040184US1) entitled “System and Method of Virtual Resource Modification on a Physical Adapter that Supports Virtual Resources”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040185US1) entitled “System and Method for Destroying Virtual Resources in a Logically Partitioned Data Processing System”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040186US1) entitled “Association of Memory Access Through Protection Attributes that are Associated to an Access Control Level on a PCI Adapter that Supports Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040187US1) entitled “Association of Host Translations that are Associated to an Access Control Level on a PCI Bridge that Supports Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040507US1) entitled “Method, Apparatus, and Computer Program Product for Coordinating Error Reporting and Reset Utilizing an I/O Adapter that Supports Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040552US1) entitled “Method and System for Fully Trusted Adapter Validation of Addresses Referenced in a Virtual Host Transfer Request”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040553US1) entitled “System, Method, and Computer Program Product for a Fully Trusted Adapter Validation of Incoming Memory Mapped I/O Operations on a Physical Adapter that Supports Virtual Adapters or Virtual Resources”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040554US1) entitled “System and Method for Host Initialization for an Adapter that Supports Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040555US1) entitled “Data Processing System, Method, and Computer Program Product for Creation and Initialization of a Virtual Adapter on a Physical Adapter that Supports Virtual Adapter Level Virtualization”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040556US1) entitled “System and Method for Virtual Resource Initialization on a Physical Adapter that Supports Virtual Resources”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040557US1) entitled “Method and System for Native Virtualization on a Partially Trusted Adapter Using Adapter Bus, Device and Function Number for Identification”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040558US1) entitled “Native Virtualization on a Partially Trusted Adapter Using PCI Host Memory Mapped Input/Output Memory Address for Identification”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040559US1) entitled “Native Virtualization on a Partially Trusted Adapter Using PCI Host Bus, Device, and Function Number for Identification; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040560US1) entitled “System and Method for Virtual Adapter Resource Allocation”; U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040561US1) entitled “System and Method for Providing Quality of Service in a Virtual Adapter”; and U.S. patent application Ser. No. ______ (Attorney Docket No. AUS920040562US1) entitled “System and Method for Managing Metrics Table Per Virtual Port in a Logically Partitioned Data Processing System” all of which are hereby incorporated by reference.  
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field  
         [0003]     The present invention relates generally to communication protocols between a host computer and an input/output (I/O) adapter. More specifically, the present invention provides an implementation for virtualizing resources on a physical I/O. In particular, the present invention provides a mechanism by which the combination of a PCI Bus address translation and protection table and a verb, such as InfiniBand verbs or RDMA protocol verbs, memory address translation and protection table can be used to associate a system image to a set of system memory addresses, such that a system image within a multiple system image virtual server can, with safety, directly expose a portion, or all, of its associated system memory to a PCI adapter that is shared by multiple system images. “With safety” in the previous sentence means that the system memory exposed by one system image is protected from access due to either the intentional or erroneous operation of the other system images sharing the PCI adapter.  
         [0004]     2. Description of Related Art  
         [0005]     Virtualization is the creation of substitutes for real resources. The substitutes have the same functions and external interfaces as their real counterparts, but differ in attributes such as size, performance, and cost. These substitutes are virtual resources and their users are usually unaware of the substitute&#39;s existence. Servers have used two basic approaches to virtualize system resources: partitioning and logical partition (LPAR) managers. Partitioning creates virtual servers as fractions of a physical server&#39;s resources, typically in coarse (e.g. physical) allocation units (e.g. a whole processor, along with its associated memory and I/O adapters). LPAR managers, sometimes referred to as hypervisors, are software or firmware components that can virtualize all server resources with fine granularity (e.g. in small fractions that of a single physical resource).  
         [0006]     Prior to this invention, servers that support virtualization had two options for handling I/O. The first option was to not allow a single physical I/O adapter to be shared between virtual servers. The second option was to add function into the LPAR manager, or another intermediary, that provides the isolation necessary to permit multiple operating systems to share a single physical adapter.  
         [0007]     The first option has several problems. One significant problem is that expensive adapters cannot be shared between virtual servers. If a virtual server only needs to use a fraction of an expensive adapter, an entire adapter would be dedicated to the server. As the number of virtual servers on the physical server increases, this leads to underutilization of the adapters and more importantly a more expensive solution, because each virtual server needs a physical adapter dedicated to it. For physical servers that support many virtual servers, another significant problem with this option is that it requires many adapter slots, with all the accompanying hardware (e.g. chips, connectors, cables, etc. . . ) required to attach those adapters to the physical server.  
         [0008]     Though the second option provides a mechanism for sharing adapters between virtual servers, that mechanism must be invoked and executed on every I/O transaction. The invocation and execution of the sharing mechanism by the LPAR manager or other intermediary on every I/O transaction degrades performance. It also leads to a more expensive solution, because the customer must purchase more hardware, either to make up for the cycles used to perform the sharing mechanism or, if the sharing mechanism is offloaded to an intermediary, for the intermediary hardware.  
         [0009]     It would be advantageous to have an improved method, apparatus, and computer instructions that allows a system image within a multiple system image virtual server to directly expose a portion, or all, of its associated system memory to a shared PCI adapter without having to go through a trusted component, such as a LPAR manager to provide isolation from the other virtual server system images. It would also be advantageous to have the mechanism apply for Ethernet NICs (Network Interface Controllers), FC (Fibre Channel) HBAs (Host Bus Adapters), PSCSI (parallel SCSI) HBAs, InfiniBand, TCP/IP Offload Engines, RDMA (Remote Direct Memory Access) enabled NICs (Network Interface Controllers), iSCSI adapters, iSER (iSCSI Extensions for RDMA) adapters, and any other type of adapter that supports a memory mapped I/O interface.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention provides a method, computer program product, and distributed data processing system that allows a system image within a multiple system image virtual server to directly expose a portion, or all, of its associated system memory to a shared PCI adapter without the need for each I/O operation to be analyzed and verified by a trusted component of the LPAR manager in order to maintain isolation from the other virtual server system images.  
         [0011]     Specifically, the present invention is directed to a mechanism for sharing conventional PCI (Peripheral Component Interconnect) I/O adapters, PCI-X I/O adapters, PCI-Express I/O adapters, and, in general, any I/O adapter that uses a memory mapped I/O interface for communications. The present invention provides a mechanism by which the combination of a PCI Bus address translation and protection table and a verb, such as InfiniBand verbs or RDMA protocol verbs, memory address translation and protection table can be used to associate a system image to a set of system memory addresses, such that a system image within a multiple system image virtual server can directly expose a portion, or all, of its associated system memory to a PCI adapter that is shared by multiple system images; while at the same time maintaining isolation of the exposed system memory from intentional or erroneous access by the other system images that share the I/O adapter.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a diagram of a distributed computer system illustrated in accordance with a preferred embodiment of the present invention;  
         [0014]      FIG. 2  is a functional block diagram of a small host processor node in accordance with a preferred embodiment of the present invention;  
         [0015]      FIG. 3  is a functional block diagram of a small, integrated host processor node in accordance with a preferred embodiment of the present invention;  
         [0016]      FIG. 4  is a functional block diagram of a large host processor node in accordance with a preferred embodiment of the present invention;  
         [0017]      FIG. 5  is a diagram illustrating the key elements of the parallel Peripheral Computer Interface (PCI) bus protocol in accordance with a preferred embodiment of the present;  
         [0018]      FIG. 6  is a diagram illustrating the key elements of the serial PCI bus protocol (PCI-Express, a.k.a. PCI-E) in accordance with a preferred embodiment of the present;  
         [0019]      FIG. 7  is a diagram illustrating the I/O virtualization functions that must be provided in a host processor node in order to provide virtual host access isolation in accordance with the present invention;  
         [0020]      FIG. 8  is a diagram illustrating the control fields used in the PCI Bus Transaction to identify a virtual adapter or system image in accordance with a preferred embodiment of the present invention;  
         [0021]      FIG. 9  is a diagram illustrating the adapter resources that must be virtualized in order to allow: an adapter to directly access virtual host resources; allow a virtual host to directly access adapter resources; and allow a non-PCI port on the adapter to access resources on the adapter or host in accordance with a preferred embodiment of the present invention;  
         [0022]      FIG. 10  is a diagram illustrating the creation of the three access control levels used to manage a PCI family adapter that supports I/O virtualization in accordance with a preferred embodiment of the present invention;  
         [0023]      FIG. 11  is a diagram illustrating how host memory that is associated with an system image is made available to a virtual adapter that is associated with that system image through the LPAR manager in accordance with a preferred embodiment of the present invention;  
         [0024]      FIG. 12  is a diagram illustrating how a PCI family adapter allows the LPAR manager to associate memory in the PCI adapter to an system image and its associated virtual adapter in accordance with a preferred embodiment of the present invention;  
         [0025]      FIG. 13  is a diagram illustrating one of the options for determining the virtual adapter that is associated with an incoming memory address to assure that the functions performed by an incoming PCI bus transaction are within the scope of the virtual adapter that is associated with the memory address referenced in the incoming PCI bus transaction translation in accordance with a preferred embodiment of the present invention;  
         [0026]      FIG. 14  is a diagram illustrating one of the options for determining the virtual adapter that is associated with an PCI-X or PCI-E bus transaction to assure that the functions performed by an incoming PCI bus transaction are within the scope of the virtual adapter that is associated with the Requestor Bus Number, Requestor Device Number, and Requestor Function Number referenced in the incoming PCI bus transaction translation in accordance with a preferred embodiment of the present invention;  
         [0027]      FIG. 15  is a diagram illustrating a virtual adapter management approach for virtualizing adapter in accordance with a preferred embodiment of the present invention;  
         [0028]      FIG. 16  is a diagram illustrating a virtual resource management approach for virtualizing adapter resources in accordance with a preferred embodiment of the present invention;  
         [0029]      FIG. 17  is a diagram illustrating an adapter virtualization approach, where an LPAR manager is responsible for managing the address translation and protection tables on the host, and the system image is responsible for controlling the address translation and protection tables on the adapter in accordance with a preferred embodiment of the present invention;  
         [0030]      FIG. 18  is a flowchart outlining the functions used to manage the adapter&#39;s address translations and protection tables;  
         [0031]      FIG. 19  is a flowchart outlining the functions performed at run-time to validate the memory access of an outbound operation on an adapter downstream port; and  
         [0032]      FIG. 20  is a flowchart outlining the functions performed at run-time to validate the memory access of an inbound operation on an adapter downstream port.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0033]     The present invention applies to any general or special purpose host that uses an I/O adapter, and in the preferred embodiment the I/O adapter is a PCI family I/O adapter that is used to directly attach storage or to attach to a network, where the network consists of endnodes, switches, router and the links interconnecting these components. The network links can be Fibre Channel, Ethernet, InfiniBand, Advanced Switching Interconnect, or a proprietary link that uses proprietary or standard protocols.  
         [0034]     With reference now to the figures and in particular with reference to  FIG. 1 , a diagram of a distributed computer system is illustrated in accordance with a preferred embodiment of the present invention. The distributed computer system represented in  FIG. 1  takes the form of a network, such as network  120  and is provided merely for illustrative purposes and the embodiments of the present invention described below can be implemented on computer systems of numerous other types and configurations. Two switches (or routers) are shown inside of network  120 , switch  116  and switch  140 , switch  116  connects to a Small Host Node, such as Small Host Node  100  through a port, such as port  112 . Small Host Node  100  also contains a second type of port, port  104 , which connects to a Direct Attached Storage subsystem, such as Direct Attached Storage  108 .  
         [0035]     Network  120  can also attach a Large Host Node, such as Large Host Node  124 , which is connected to Network  120 , through port  136  which attaches to switch  140 . Large Host Node  124  can also contain a second type of port, such as port  128 , which connects to a Direct Attached Storage subsystem, such as Direct Attached Storage  132 .  
         [0036]     Network  120  can also attach a Small Integrated Host Node, such as Small Integrated Host Node  144 , which is connected to Network  120 , through port  148  which attaches to switch  140 . Small Integrated Host Node  144  can also contain a second type of port, such as port  152 , which connects to a Direct Attached Storage subsystem, such as Direct Attached Storage  156 .  
         [0037]     Turning next to  FIG. 2 , a functional block diagram of a Small Host Node is depicted in accordance with a preferred embodiment of the present invention. Small Host Node  202  is an example of a host processor node, such as Small Host Node  100  in  FIG. 1 .  
         [0038]     In this example, Small Host Node  202 , shown in  FIG. 2 , includes two Processor I/O Hierarchies, such as Processor I/O Hierarchy  200  and  203 , which are interconnected through link  201 . In  FIG. 2  Processor I/O Hierarchy  200  is drawn completely, and it includes a Processor Chip, such as Processor Chip  207 , which includes one or more processors and their associated caches. Processor Chip  207  is connected to memory, such as memory  212 , through a link, such as link  208 . One of the links on the Processor Chip, such as link  220 , connects to a PCI Family I/O Bridge, such as PCI Family I/O Bridge  228 . The PCI Family I/O Bridge  228  has one or more PCI family (PCI, PCI-X, PCI-Express, or any future generation of PCI) links that are used to connect other PCI family I/O bridges or a PCI family I/O adapter, such as PCI Family Adapter  1   244  and PCI Family Adapter  2   245  through a PCI link, such as link  232 ,  236 , and  240 . PCI Family Adapter  1   245  can also be used to connect a network, such as Network  264 , through a link, such as  256 , using either a Switch or Router, such as Switch Or Router  260 . PCI Family Adapter  2   244  can be used to connect Direct Attached Storage, such as Direct Attached Storage  252 , through a link, such as link  248 .  
         [0039]     With reference now to  FIG. 3 , a functional block diagram of a Small Integrated Host Node is depicted in accordance with a preferred embodiment of the present invention. Small Integrated Host Node  302  is an example of a host processor node, such as Small Integrated Host Node  144  in  FIG. 1 .  
         [0040]     In this example, Small Integrated Host Node  302 , shown in  FIG. 3 , includes two Processor I/O Hierarchies, such as Processor I/O Hierarchy  300  and  303 , which are interconnected through link  301 . In  FIG. 3  Processor I/O Hierarchy  300  is drawn completely, and it includes a Processor Chip, such as Processor Chip  304 , which includes one or more processors and their associated caches. Processor Chip  304  is connected to memory, such as memory  312 , through a link, such as link  308 . The Processor Chip  304  has one or more PCI family (PCI, PCI-X, PCI-Express, or any future generation of PCI) links that are used to connect either PCI family I/O bridges or a PCI family I/O adapter, such as PCI Family Adapter  1   345  and PCI Family Adapter  2   344  through a PCI link, such as link  316 ,  330 , and  324 . PCI Family Adapter  1   345  can also be used to connect a network, such as Network  364 , through a link, such as  356 , using either a Switch or Router, such as Switch Or Router  360 . PCI Family Adapter  2   344  can be used to connect Direct Attached Storage, such as Direct Attached Storage  352 , through a link, such as link  348 .  
         [0041]     Turning now to  FIG. 4 , a functional block diagram of a Large Host Node is depicted in accordance with a preferred embodiment of the present invention. Large Host Node  402  is an example of a host processor node, such as Large Host Node  124  in  FIG. 1 .  
         [0042]     In this example, Large Host Node  402 , shown in  FIG. 4 , includes two Processor I/O Hierarchies, such as Processor I/O Hierarchy  400  and  403 , which are interconnected through link  401 . In  FIG. 4  Processor I/O Hierarchy  400  includes a Processor Chip, such as Processor Chip  404 , which includes one or more processors and their associated caches. Processor Chip  404  is connected to memory, such as memory  412 , through a link, such as link  408 . One of the links on the Processor Chip, such as link  440 , connects to a PCI Family I/O Hub, such as PCI Family I/O Hub  441 . The PCI Family I/O Hub uses a network, such as Network  442 , to attach to a PCI Family I/O Bridge, such as PCI Family I/O Bridge  448 . That is, PCI Family I/O Bridge  448  is connected to Switch or Router  436  through link  432  and Switch or Router  436  also attaches to PCI Family I/O Hub  441  through link  443 . Network  442  allows the PCI Family I/O Hub and PCI Family I/O Bridge to be placed in different packages. PCI Family I/O Bridge  448  has one or more PCI family (PCI, PCI-X, PCI-Express, or any future generation of PCI) links that are used to connect other PCI family I/O bridges or a PCI family I/O adapter, such as PCI Family Adapter  456  and PCI Family Adapter  2   457  through a PCI link, such as link  444 ,  448 , and  452 . PCI Family Adapter  1   456  can be used to connect Direct Attached Storage, such as Direct Attached Storage  476 , through a link, such as link  460 . PCI Family Adapter  2   457  can also be used to connect a network, such as Network  464 , through a link, such as  468 , using either a Switch or Router, such as Switch Or Router  472 .  
         [0043]     Also shown in  FIG. 4 , Processor I/O Hierarchy  403  includes a Processor Chip, such as Processor Chip  405 , which includes one or more processors and their associated caches. Processor Chip  405  is connected to memory, such as memory  413 , through a link, such as link  409 . One of the links on the Processor Chip, such as link  418 , connects to a non-PCI I/O Hub, such as non-PCI I/O Hub  419 . The non-PCI I/O Hub uses a network, such as Network  492 , to attach to a non-PCI to PCI I/O Bridge, such as non-PCI to PCI I/O Bridge  488 . That is, non-PCI to PCI I/O Bridge  488  is connected to Switch or Router  494  through link  490  and Switch or Router  494  also attaches to non-PCI I/O Hub  419  through link  496 . Network  492  allows the non-PCI I/O Hub  419  and non-PCI to PCI I/O Bridge  488  to be placed in different packages. Non-PCI to PCI I/O Bridge  488  has one or more PCI family (PCI, PCI-X, PCI-Express, or any future generation of PCI) links that are used to connect other PCI family I/O bridges or a PCI family I/O adapter, such as PCI Family Adapter  1   480  and PCI Family Adapter  2   474  through a PCI link, such as link  482 ,  484 , and  486 . PCI Family Adapter  1   480  can be used to connect Direct Attached Storage, such as Direct Attached Storage  476 , through a link, such as link  478 . PCI Family Adapter  2   457  can also be used to connect a network, such as Network  464 , through a link, such as  473 , using either a Switch or Router, such as Switch Or Router  472 .  
         [0044]     Turning next to  FIG. 5 , an illustration of the phases contained in a conventional PCI bus transaction, such as PCI  500 , and a PCI-X bus transaction, such as PCI-X  520  is depicted in accordance with a preferred embodiment of the present invention. PCI  500  depicts the conventional PCI bus transaction that forms the unit of information which is transferred through a PCI fabric for conventional PCI. PCI-X  520  depicts the PCI-X bus transaction that forms the unit of information which is transferred through a PCI fabric for PCI-X.  
         [0045]     PCI  500  shows three phases: an address phase, such as Address Phase  508 ; a data phase, such as Data Phase  512 ; and a turnaround cycle, such as Turnaround Cycle  516 . Also depicted is the Arbitration for next transfer,  504 , which can occur simultaneously with the three phases. For conventional PCI, the address contained in the Address Phase is used to route a bus transaction from the adapter to the host and from the host to the adapter.  
         [0046]     PCI-X  520  shows five phases: an address phase, such as Address Phase  528 ; an attribute phase, such as Attribute Phase  532 ; a response phase, such as Response Phase  560 ; a data phase, such as Data Phase  564 ; and a turnaround cycle, such as Turnaround Cycle  566 . Also depicted is the Arbitration for next transfer,  524 , which can occur simultaneously with the three phases. Similar to conventional PCI, PCI-X uses the address contained in the Address Phase to route a bus transaction from the adapter to the host and from the host to the adapter. However, PCI-X adds the Attribute Phase  532 , which contains three fields that define the bus transaction Requestor, these three fields are the: Requestor Bus Number  544 , Requestor Device Number  548 , and Requestor Function Number  552 . The bus transaction also contains a Misc field  536 , and a Tag  540  which uniquely identifies the specific bus transaction in relation to other bus transactions that are outstanding between the Requestor and the Responder. The Byte Count  556  contains a count of the number of bytes being sent.  
         [0047]     Turning now to  FIG. 6 , an illustration of the phases contained in a PCI-Express bus transaction, such as PCI-E  600  is depicted in accordance with a preferred embodiment of the present invention. The PCI-E bus transaction depicted in  600  forms the unit of information which is transferred through a PCI fabric for PCI-E.  
         [0048]     PCI-E  600  shows six phases: a frame phase, such as Frame  608 ; a sequence number, such as Sequence Number  612 ; a header, such as Header  664 ; a data phase, such as Data Phase  668 ; a Cyclical Redundancy Check, such as CRC  672 ; and a frame phase, such as Frame  680 . The PCI-E Header, such as Header  664 , contains a set of fields defined in the PCI-Express specification, including Address/Routing information  640 . The Requestor Identifier field, such as Requestor ID  628 , contains three fields that define the bus transaction Requestor, these three fields are the: Requestor Bus Number  684 , Requestor Device Number  688 , and Requestor Function Number  692 . The PCI-E Header also contains a Tag  652 , which uniquely identifies the specific bus transaction in relation to other bus transactions that are outstanding between the Requestor and the Responder. The remaining Header fields, including Length  644 , Attr  648 , Reserved  656 , Byte Enables  660 , Fmt  620 , Type  624 , Reserved  632  and Traffic Class  636 , are defined in the PCI-Express specification and need not be further described herein.  
         [0049]     With reference now to  FIG. 7 , a functional block diagram of a PCI adapter, such as PCI Family Adapter  736 , and the firmware and software that runs on host hardware (e.g. processor with possibly an I/O Hub or I/O Bridge), such as Host Hardware  700 , is depicted in accordance with a preferred embodiment of the present invention.  
         [0050]      FIG. 7  also shows a LPAR manager, such as Hypervisor  708 , running on Host Hardware  700 . Hypervisor  708  can run in firmware, software, or a combination of the two. Hypervisor  708  hosts two System Image partitions, such as System Image  1   712  and System Image  2   724 . The System Image partitions may be an Operating System running in software, a special purpose image running in software, such as a storage block server or storage file server image, or a special purpose image running in firmware. Applications can run on these System Images, such as Application  1 A  716 , Application  2   720 , Application  1 B  728 , and Application  3   732 .  
         [0051]     PCI Family Adapter  736  contains a set of Physical Adapter Configuration Resources, such as Physical Adapter Configuration Resources  740 , and Physical Adapter Memory Resources, such as Physical Adapter Memory Resources  744 . The Physical Adapter Configuration Resources  740  and Memory  744  contain information describing the number of virtual adapters that PCI Family Adapter  736  can support and the physical resources allocated to each virtual adapter. Hypervisor  708  is provided a physical configuration resource interface, such as  738 , and memory interface, such as  742 , to read and write into the Physical Adapter Configuration Resource and Memory spaces during the adapter&#39;s initial configuration and reconfiguration. Through the physical configuration resource interface  738  and physical configuration memory interface  742 , Hypervisor  708  creates virtual adapters and assigns physical resources to each virtual adapter. The Hypervisor  708  may use one of the System Images, for example a special software or firmware partition, as a hosting partition that uses physical configuration resource interface  738  and physical configuration memory interface  742  to perform a portion, or even all, of the virtual adapter initial configuration and reconfiguration functions.  
         [0052]      FIG. 7  shows two Virtual Adapters. Virtual Adapter 1 contains the set of Virtual Adapter Resources, such as Virtual Adapter 1 Resources  748 , and Virtual Adapter Memory, such as Virtual Adapter 1 Memory  752 , that were assigned by Hypervisor  708  to Virtual Adapter 1 and associated with an System Image, such as System Image  1   712 . Similarly, Virtual Adapter 2 contains the set of Virtual Adapter Resources, such as Virtual Adapter 2 Resources  756 , and Virtual Adapter Memory, such as Virtual Adapter 2 Memory  760 , that were assigned by Hypervisor  708  to Virtual Adapter 2 and associated with an System Image, such as System Image  2   724 . For an adapter used to connect to Direct Attached Storage, such as Direct Attached Storage  108 ,  132 , or  156  (as shown in  FIG. 1 ), examples of Virtual Adapter Resources may include: the list of the associated physical disks, a list of the associated Logical Unit Numbers, and a list of the associated adapter functions (e.g. RAID level). For an adapter used to connect to a Network, such as Network  120  (as shown in  FIG. 1 ), examples of Virtual Adapter Resources may include: the list of the associated link level identifiers, a list of the associated network level identifiers, a list of the associated virtual fabric identifiers (e.g. Virtual LAN IDs for Ethernet fabrics, N-port IDs for Fibre Channel fabrics, and Partition Keys for InfiniBand fabrics), and a list of the associated network layers functions (e.g. network offload services).  
         [0053]     After the Hypervisor  708  configures the PCI Family Adapter  736 , each System Image is allowed to only communicate with the Virtual Adapters that were associated with that System Image by Hypervisor  708 . As shown in  FIG. 7  at  768  and  764 , System Image 1 is allowed to communicate with Virtual Adapter 1 Resources  748  and Virtual Adapter 1 Memory  752  directly.  FIG. 7  at  778  and  782  also shows that System Image 1 is not allowed to communicate with Virtual Adapter 2 Resources  756  and Virtual Adapter 2 Memory  760  directly. Similarly,  FIG. 7  at  774  and  772  shows that System Image  2  is allowed to communicate with Virtual Adapter 2 Resources  756  and Virtual Adapter 1 Memory  760  directly.  FIG. 7  at  786  and  790  also shows that System Image 2 is not allowed to communicate with Virtual Adapter 1 Resources  748  and Virtual Adapter 1 Memory  752  directly.  
         [0054]     With reference now to  FIG. 8 , there is depicted a component, such as Processor, I/O Hub, or I/O Bridge  800 , inside a host node, such as Small Host Node  100 , Large Host Node  124 , or Small, Integrated Host Node  144 , that attaches a PCI Family Adapter, such as PCI Family Adapter  804 , through a PCI-X or PCI-E link, such as PCI-X or PCI-E Link  808  in accordance with a preferred embodiment of the present invention.  
         [0055]      FIG. 8  shows that when a System Image, such as System Image  1   712  or System Image  2   724 , or a LPAR manager, such as Hypervisor  708 , performs a PCI-X or PCI-E bus transactions, such as Host to Adapter PCI-X or PCI-E Bus Transaction  812 , the Processor, I/O Hub, or I/O Bridge  800  that connects to the PCI-X or PCI-E Link  808  which issues the Host to Adapter PCI-X or PCI-E Bus Transaction  812  must fill in the Bus Number, Device Number, and Function Number fields in the PCI-X or PCI-E bus transaction  812 . The Processor, I/O Hub, or I/O Bridge  800  has two choices for how to fill in these three fields: it can either use the same Bus Number, Device Number, and Function Number for all software components that use the Processor, I/O Hub, or I/O Bridge  800 ; or it can use a different Bus Number, Device Number, and Function Number for each software component that uses the Processor, I/O Hub, or I/O Bridge  800 . The software component can be a System Image, such as System Image  1   712  or System Image  2   724 , or a LPAR manager, such as Hypervisor  708 . It should also be noted that this invention applies not just to the PCI Family, but to any Memory Mapped I/O interface, such as HyperTransport, Rapid I/O, proprietary Memory Mapped I/O interfaces, or some new standard Memory Mapped I/O interface.  
         [0056]     If the Processor, I/O Hub, or I/O Bridge  800  uses the same Bus Number, Device Number, and Function Number for all software components, then when a software component initiates a PCI-X or PCI-E bus transaction, such as Host to Adapter PCI-X or PCI-E Bus Transaction  812 , the Processor, I/O Hub, or I/O Bridge  800  places the Processor, I/O Hub, or I/O Bridge&#39;s bus number in the PCI-X or PCI-E bus transaction&#39;s Requestor Bus Number, such as Requestor Bus Number  544  or Requestor Bus Number  684 . This is shown in  FIG. 8  as Host Bus Number  820 . Similarly, the Processor, I/O Hub, or I/O Bridge  800  places the Processor, I/O Hub, or I/O Bridge&#39;s device number in the PCI-X or PCI-E bus transaction&#39;s Requestor Device Number, such as Requestor Bus Number  548  or Requestor Device Number  688 . This is shown in  FIG. 8  as Host Device Number  824 . Finally, the Processor, I/O Hub, or I/O Bridge  800  places the Processor, I/O Hub, or I/O Bridge&#39;s function number in the PCI-X or PCI-E bus transaction&#39;s Requestor Function Number, such as Requestor Bus Number  552  or Requestor Function Number  692 . This is shown in  FIG. 8  as Host Function Number  828 . The Processor, I/O Hub, or I/O Bridge  800  also places in the PCI-X or PCI-E bus transaction the Physical or Virtual Adapter memory address that is targeted by the software component. This is shown in  FIG. 8  as Adapter Resource or Address  816 .  
         [0057]     If the Processor, I/O Hub, or I/O Bridge  800  uses a different Bus Number, Device Number, and Function Number for each software component, then the Processor, I/O Hub, or I/O Bridge  800  must assign a Bus Number, Device Number, and Function Number to the software component. When the software component initiates a PCI-X or PCI-E bus transaction, such as Host to Adapter PCI-X or PCI-E Bus Transaction  812 , the Processor, I/O Hub, or I/O Bridge  800  places the software component&#39;s bus number in the PCI-X or PCI-E bus transaction&#39;s Requestor Bus Number, such as Requestor Bus Number  544  or Requestor Bus Number  684 . This is shown in  FIG. 8  as Host Bus Number  820 . Similarly, the Processor, I/O Hub, or I/O Bridge  800  places the software component&#39;s device number in the PCI-X or PCI-E bus transaction&#39;s Requestor Device Number, such as Requestor Bus Number  548  or Requestor Device Number  688 . This is shown in  FIG. 8  as Host Device Number  824 . Finally, the Processor, I/O Hub, or I/O Bridge  800  places the software component&#39;s function number in the PCI-X or PCI-E bus transaction&#39;s Requestor Function Number, such as Requestor Bus Number  552  or Requestor Function Number  692 . This is shown in  FIG. 8  as Host Function Number  828 . The Processor, I/O Hub, or I/O Bridge  800  also places in the PCI-X or PCI-E bus transaction the Physical or Virtual Adapter memory address that is targeted by the software component. This is shown in  FIG. 8  as Adapter Resource or Address  816 .  
         [0058]      FIG. 8  also shows that when a physical or virtual adapter, such as Physical or Virtual Adapter  806  performs PCI-X or PCI-E bus transactions, such as Adapter to Host PCI-X or PCI-E Bus Transaction  832 , the PCI Family Adapter, such as Physical Family Adapter  804 , that connects to the PCI-X or PCI-E Link  808  which issues the Adapter to Host PCI-X or PCI-E Bus Transaction  832  must fill in the Bus Number, Device Number, and Function Number of the associated bus transaction with the Physical or Virtual Adapter that initiated the bus transaction. It should be noted that to support more than one Bus or Device Number, PCI Family Adapter  804  must support one or more internal busses (For a PCI-X Adapter, see the PCI-X Addendum to the PCI Local Bus Specification Revision 1.0 or 1.0a; for a PCI-E Adapter see PCI-Express Base Specification Revision 1.0 or 1.0a). Also, to perform this function, Hypervisor  708  associates each Physical or Virtual Adapter to a software component running, by assigning a Bus Number, Device Number, and Function Number to the Physical or Virtual Adapter. When the Physical or Virtual Adapter initiates an Adapter to Host PCI-X or PCI-E Bus Transaction, the PCI Family Adapter  804  places the Physical or Virtual Adapter&#39;s bus number in the PCI-X or PCI-E bus transaction&#39;s Requestor Bus Number, such as Requestor Bus Number  544  or Requestor Bus Number  684 . This is shown in  FIG. 8  as Adapter Bus Number  836 . Similarly, PCI Family Adapter  804  places the Physical or Virtual Adapter&#39;s device number in the PCI-X or PCI-E bus transaction&#39;s Requestor Device Number, such as Requestor Bus Number  548  or Requestor Device Number  688 . This is shown in  FIG. 8  as Adapter Device Number  840 . Finally, PCI Family Adapter  804  places the Physical or Virtual Adapter&#39;s function number in the PCI-X or PCI-E bus transaction&#39;s Requestor Function Number, such as Requestor Bus Number  552  or Requestor Function Number  692 . This is shown in  FIG. 8  as Adapter Function Number  844 . The PCI Family Adapter  804  also places in the PCI-X or PCI-E bus transaction the memory address of the system storage assigned to the software component that is associated with, and targeted by, the Physical or Virtual Adapter. This is shown in  FIG. 8  as Host Resource or Address  848 .  
         [0059]     With reference now to  FIG. 9 , a functional block diagram of a PCI adapter, such as PCI Family Adapter  900 , with two virtual adapters, such as Virtual Adapter  1   916  and Virtual Adapter  2   920 , is depicted in accordance with a preferred embodiment of the present invention. A PCI adapter, such as PCI Family Adapter  900 , may contain one (or more) PCI family ports, such as PCI-X or PCI-E Port  912 . A PCI adapter, such as PCI Family Adapter  900 , may also contain one (or more) device or network ports, such as Physical Port  1   904  and Physical Port  2   908 .  
         [0060]      FIG. 9  also shows the types of resources that can be virtualized on a PCI adapter, such as PCI Family Adapter  900 . The resources on Virtual Adapter  1   916  that may be virtualized include: processing queues, such as Processing Queues  924 , address and configuration memory, such as Address and Configuration Memory  928 , PCI ports, such as PCI Port  936 , host memory management resources (e.g. such as memory region registration and memory window binding resources on InfiniBand or iWARP), such as Host Memory Management Resources  984 , and device or network ports, such as External Port  1   932  and External Port  2   934 . For Virtual Adapter  2   920  the resources that may be virtualized include: processing queues, such as Processing Queues  940 , address and configuration memory, such as Address and Configuration Memory  944 , PCI ports, such as PCI Port  952 , host memory management resources, such as Host Memory Management Resources  980 , and device or network ports, such as External Port  1   948  and External Port  2   950 .  
         [0061]     Turning next to  FIG. 10 , a functional block diagram of the access control levels on a PCI Family Adapter, such as PCI Family Adapter  900 , is depicted in accordance with a preferred embodiment of the present invention. The three levels of access are a Super-Privileged Physical Resource Allocation Level, such as Super-Privileged Physical Resource Allocation Level  1000 , a Privileged Virtual Resource Allocation Level, such as Privileged Virtual Resource Allocation Level  1008 , and a Non-Privileged Level, such as Non-Privileged Level  1016 .  
         [0062]     The functions performed at the Super-Privileged Physical Resource Allocation Level  1000  include: PCI Family Adapter queries, creation of virtual adapters, submission and retrieval of work, and allocation of physical resources to a virtual adapter instance. The PCI Family Adapter queries are used to determine: the physical adapter type (e.g. Fibre Channel, Ethernet, iSCSI, parallel SCSI), the functions supported on the physical adapter, and the number of virtual adapters supported by the PCI Family Adapter. A LPAR manager, such as Hypervisor  708 , performs the Physical Adapter Resource Management  1004  functions associated with Super-Privileged Physical Resource Allocation Level  1000 . However, the LPAR manager may use a System Image, for example an I/O Hosting Partition, to perform the Physical Adapter Resource Management  1004  functions.  
         [0063]     The functions performed at the Privileged Virtual Resource Allocation Level  1008  include: virtual adapter queries, allocation and initialization of virtual adapter resources, submission and retrieval of work through virtual adapter resources, and, for virtual adapters that support offload services: allocation and assignment of virtual adapter resources to a middleware process or thread instance. The virtual adapter queries are used to determine: the virtual adapter type (e.g. Fibre Channel, Ethernet, iSCSI, parallel SCSI) and the functions supported on the virtual adapter. A System Image, such as System Image  1   712 , performs the Privileged Virtual Adapter Resource Management  1012  functions associated with Virtual Resource Allocation Level  1008 .  
         [0064]     Finally, the functions performed at the Non-Privileged Level  1016  include: query of virtual adapter resources that have been assigned to software running at the Non-Privileged Level  1016  and submission and retrieval of work through virtual adapter resources that have been assigned to software running at the Non-Privileged Level  1016 . An application, such as Application  1 A  716 , performs the Virtual Adapter Access Library  1020  functions associated with Non-Privileged Level  1016 .  
         [0065]     Turning next to  FIG. 11 , a functional block diagram of the host memory addresses that are made accessible to a PCI Family Adapter, such as PCI Family Adapter  1101 , is depicted in accordance with a preferred embodiment of the present invention.  
         [0066]      FIG. 11  depicts four different mechanisms by which a LPAR manager, such as Hypervisor  1190  can associate Host Memory  1176  assigned to a System Image, such as System Image  1   1108  or System Image  2   1116 , with a Virtual Adapter, such as Virtual Adapter  1   1104  or Virtual Adapter  2   1112 . Once Host Memory has been associated to a System Image and a Virtual Adapter, the Virtual Adapter can then perform Direct Memory Access (DMA) Write and Read operations directly to/from the Host Memory  1176 .  
         [0067]     The first mechanism that Hypervisor  1190  can use to associate and make available Host Memory to a System Image and to one or more Virtual Adapters is to write into the Virtual Adapter&#39;s Resources a page size and page list  1122 . In  FIG. 11 , Virtual Adapter 1 Resources  1120  contains a list of PCI Bus Addresses, where each PCI Bus Address in the list is associated by the Platform Hardware to the starting address of a System Image page, such as SI 1 Page  1   1128  through SI 1 Page N  1136 . Virtual Adapter 1 Resources  1120  also contains the page size, which must be equal for all the pages in the list. At initial configuration, and during reconfigurations, Hypervisor  1190  loads the page size and page list  1122  into the Virtual Adapter 1 Resources  1120 . The page size and page list  1122  define the set of addresses (as indicated at  1124  and  1132 ) that Virtual Adapter  1   1104  can use in Direct Memory Access (DMA) Write and Read Operations. After the page size and page list  1122  have been created, Virtual Adapter  1   1104  must validate that each DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in the page size and page list  1122 . If the DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in the page size and page list  1122 , then Virtual Adapter  1   1104  may perform the operation. Otherwise Virtual Adapter  1   1104  must not perform the operation. Instead of Virtual Adapter  1   1104 , the PCI Family Adapter  1101  may use a special, LPAR manager style Virtual Adapter to perform the check that determines if DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in the page size and page list  1122 .  
         [0068]     The second mechanism that Hypervisor  1190  can use to associate and make available Host Memory to a System Image and to one or more Virtual Adapters is to write into the Virtual Adapter&#39;s Resources a starting page address and page size  1122  for a single page. In  FIG. 11 , Virtual Adapter 1 Resources  1120  contains a single PCI Bus Address that is associated by the Platform Hardware to the starting address of a System Image page, such as SI 1 Page  1   1128 . Virtual Adapter 1 Resources  1120  also contains the size of the page. At initial configuration, and during reconfigurations, Hypervisor  1190  loads the page size and starting page address into starting page address and size resource  1122  into the Virtual Adapter 1 Resources  1120 . The starting page address and size resource  1122  defines the set of addresses that Virtual Adapter  1   1104  can use in Direct Memory Access (DMA) Write and Read Operations. After the starting page address and size resource  1122  has been created, Virtual Adapter  1   1104  must validate that each DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in starting page address and size resource  1122 . If the DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in the starting page address and size resource  1122 , then Virtual Adapter  1   1104  may perform the operation. Otherwise Virtual Adapter  1   1104  must not perform the operation. Instead of Virtual Adapter  1   1104 , the PCI Family Adapter  1101  may use a special, LPAR manager style Virtual Adapter to perform the check that determines if DMA Write or DMA Read requested by System Image  1   1108  is contained within a page in the starting page address and size resource  1122 .  
         [0069]     The third mechanism that Hypervisor  1190  can use to associate and make available Host Memory to a System Image and to one or more Virtual Adapters is to write into the Virtual Adapter&#39;s Resources a list of different sized buffers  1154 . In  FIG. 11 , Virtual Adapter 2 Resources  1150  contains a list of PCI Bus Address pairs (starting and ending address), where each pair of PCI Bus Address in the list is associated by the Platform Hardware to a pair (starting and ending) of addresses of a System Image buffer, such as SI 2 Buffer  1   1166  through SI 1 Buffer N  1180 . At initial configuration, and during reconfigurations, Hypervisor  1190  loads the buffer list of different sized buffers  1154  into the Virtual Adapter 2 Resources  1150 . The list of different sized buffers  1154  defines the set of addresses (as indicated at  1158 ,  1162 ,  1172  and  1174 ) that Virtual Adapter  2   1112  can use in Direct Memory Access (DMA) Write and Read Operations. After the list of different sized buffers  1154  has been created, Virtual Adapter  2   1112  must validate that each DMA Write or DMA Read requested by System Image  2   1116  is contained within a buffer in list of different sized buffers  1154 . If the DMA Write or DMA Read requested by System Image  2   1116  is contained within a buffer in the list of different sized buffers  1154 , then Virtual Adapter  2   1112  may perform the operation. Otherwise Virtual Adapter  2   1112  must not perform the operation. Instead of Virtual Adapter  2   1112 , the PCI Family Adapter  1101  may use a special, LPAR manager style Virtual Adapter to perform the check that determines if DMA Write or DMA Read requested by System Image  2   1116  is contained within a buffer in the list of different sized buffers  1154 .  
         [0070]     The fourth mechanism that Hypervisor  1190  can use to associate and make available Host Memory to a System Image and to one or more Virtual Adapters is to write into the Virtual Adapter&#39;s Resources a single starting and ending address. In  FIG. 11 , Virtual Adapter 2 Resources  1150  contains a single PCI Bus starting and ending address that is associated by the Platform Hardware to a pair (starting and ending) of addresses associated with a System Image buffer, such as SI 2 Buffer  1   1166 . At initial configuration, and during reconfigurations, Hypervisor  1190  loads SI 2 Buffer  1 &#39;s  1166  starting and ending address into the Virtual Adapter 2 Resources buffer starting and ending address resource  1154 . The starting and ending address resource  1154  then defines the set of addresses that Virtual Adapter  2   1112  can use in Direct Memory Access (DMA) Write and Read Operations. After the starting and ending address resource  1154  has been created, Virtual Adapter  2   1112  must validate that each DMA Write or DMA Read requested by System Image  2   1116  is contained within the starting and ending address resource  1154 . If the DMA Write or DMA Read requested by System Image  2   1116  is contained within a starting and ending address resource  1154 , then Virtual Adapter  2   1112  may perform the operation. Otherwise Virtual Adapter  2   1112  must not perform the operation. Instead of Virtual Adapter  2   1112 , the PCI Family Adapter  1101  may use a special, LPAR manager style Virtual Adapter to perform the check that determines if DMA Write or DMA Read requested by System Image  2   1116  is contained within a page in  1154 .  
         [0071]     Turning next to  FIG. 12 , a functional block diagram of the PCI Family Adapter, such as PCI Family Adapter  1201 , memory addresses that are made accessible to a System Image, such as System Image  1   1208  or System Image  2   1216 , is depicted in accordance with a preferred embodiment of the present invention.  
         [0072]      FIG. 12  depicts four different mechanisms by which a LPAR manager, such as Hypervisor  1294  can associate PCI Family Adapter Memory to a Virtual Adapter, such as Virtual Adapter  1   1204 , and to a System Image, such as System Image  1   1208 . Once PCI Family Adapter Memory has been associated to a System Image and a Virtual Adapter, the System Image can then perform Programmed I/O Write and Read (a.k.a. Store and Load) operations directly to the PCI Family Adapter Memory.  
         [0073]     There is a key difference between  FIG. 11  and  FIG. 12 . In  FIG. 11  the PCI Family Adapter only holds a list of host addresses that do not have any local memory associated with them. If the PCI Family Adapter supports flow-through traffic, then data arriving on an external port can directly flow through the PCI Family Adapter and be transferred, through DMA Writes, directly into these host addresses. Similarly, if the PCI Family Adapter supports flow-through traffic, then the data from these host addresses can directly flow through the PCI Family Adapter and be transferred out to an external port. In  FIG. 12  the PCI Family Adapter has local adapter memory that is associated with the list of host memory addresses. The PCI Family Adapter can initiate: DMA Writes from its local memory to the host memory or DMA Reads from the host memory to its local memory. Similarly, the host can initiate: Programmed I/O Writes (a.k.a. Stores) from its local memory to the PCI Family Adapter memory or Programmed I/O Reads (a.k.a. Loads) from the PCI Family Adapter memory to the host&#39;s local memory.  
         [0074]     The first and second mechanisms that Hypervisor  1294  can use to associate and make available PCI Family Adapter Memory to a System Image and to a Virtual Adapter is to write into the PCI Family Adapter&#39;s Physical Adapter Memory Translation Table  1290  a page size and the starting address of one (first mechanism) or more (second mechanism) pages. In this case all pages have the same size. For example,  FIG. 12  depicts a set of pages that have been mapped (as indicated at  1224  and  1232 ) between the System Image  1   1208  and Virtual Adapter  1   1204 : SI 1 Page  1   1240  through SI 1 Page N  1242 . For System Image 1, all pages in the list have the same size. At initial configuration, and during reconfigurations, Hypervisor  1294  loads the PCI Family Adapter&#39;s Physical Adapter Memory Translation Table  1290  with the page size and the starting address of one or more pages. The Physical Adapter Memory Translation Table  1290  then defines the set of addresses that Virtual Adapter  1   1204  can use in Direct Memory Access (DMA) Write and Read Operations. After Physical Adapter Memory Translation Table  1290  has been created, PCI Family Adapter  1201  (or Virtual Adapter  1   1204 ) must validate that each DMA Write or DMA Read requested by System Image  1   1208  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  1   1204 . If the DMA Write or DMA Read requested by System Image  1   1208  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  1   1204 , then Virtual Adapter  1   1204  may perform the operation. Otherwise Virtual Adapter  1   1204  must not perform the operation. The Physical Adapter Memory Translation Table  1290  also defines the set of addresses that System Image  1   1208  can use in Programmed I/O (PIO) Write and Read Operations. After Physical Adapter Memory Translation Table  1290  has been created, PCI Family Adapter  1201  (or Virtual Adapter  1   1204 ) must validate that Programmed I/O Write or Read requested by System Image  1   1208  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  1   1204 . If the PIO Write or PIO Read requested by System Image  1   1208  is contained in the Physical Adapter Memory Translation Table  1290  associated with Virtual Adapter  1   1204 , then Virtual Adapter  1   1204  may perform the operation. Otherwise Virtual Adapter  1   1204  must not perform the operation.  
         [0075]     The third and fourth mechanisms that Hypervisor  1294  can use to associate and make available PCI Family Adapter Memory to a System Image and to a Virtual Adapter is to write into the PCI Family Adapter&#39;s Physical Adapter Memory Translation Table  1290  one (third mechanism) or more (fourth mechanism) buffer starting and ending addresses (or starting address and length). In this case, the buffers may have different sizes. For example,  FIG. 12  depicts a set of varying sized buffers that have been mapped (as indicated at  1258 ,  1262 ,  1270  and  1274 ) between the System Image  2   1216  and Virtual Adapter  2   1212 : SI 2 Buffer  1   1244  through SI 2 Buffer N  1248 . For System Image 2, the buffers in the list have different sizes. At initial configuration, and during reconfigurations, Hypervisor  1294  loads the PCI Family Adapter&#39;s Physical Adapter Memory Translation Table  1290  with the starting and ending address (or starting address and length) of one or more pages. The Physical Adapter Memory Translation Table  1290  then defines the set of addresses that Virtual Adapter  2   1212  can use in Direct Memory Access (DMA) Write and Read Operations. After Physical Adapter Memory Translation Table  1290  has been created, PCI Family Adapter  1201  (or Virtual Adapter  2   1212 ) must validate that each DMA Write or DMA Read requested by System Image  2   1216  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  2   1212 . If the DMA Write or DMA Read requested by System Image  2   1216  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  2   1212 , then Virtual Adapter  2   1212  may perform the operation. Otherwise Virtual Adapter  2   1212  must not perform the operation. The Physical Adapter Memory Translation Table  1290  also defines the set of addresses that System Image  2   1212  can use in Programmed I/O (PIO) Write and Read Operations. After Physical Adapter Memory Translation Table  1290  has been created, PCI Family Adapter  1201  (or Virtual Adapter  2   1212 ) must validate that Programmed I/O Write or Read requested by System Image  2   1216  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  2   1212 . If the PIO Write or PIO Read requested by System Image  2   1216  is contained in the Physical Adapter Memory Translation Table  1290  and associated with Virtual Adapter  2   1212 , then Virtual Adapter  2   1212  may perform the operation. Otherwise Virtual Adapter  2   1212  must not perform the operation.  
         [0076]     With reference next to  FIG. 13 , a functional block diagram of the PCI Family Adapter, such as PCI Family Adapter  1300 , Physical Address Memory Translation Table, such as Buffer Table  1390  or Page Table  1392 , is depicted in accordance with a preferred embodiment of the present invention.  
         [0077]      FIG. 13  depicts four mechanisms for how the address referenced in an incoming PCI Bus Transaction, such as Bus Transaction  1304 , can be used to look up the Virtual Adapter Resources (including the local PCI Family Adapter memory address that has been mapped to the host address), such as Virtual Adapter 1 Resources  1398  and Virtual Adapter 2 Resources  1394 , associated with that memory address.  
         [0078]     The first mechanism is to compare the incoming PCI Bus Transaction&#39;s, such as Bus Transaction  1304 , memory address  1308  with each row of High Address  1316  and Low Address  1320  in the Buffer Table  1390  as shown by arrow  1312 . If the incoming PCI Bus Transaction, such as Bus Transaction  1304 , has an address that is lower than the contents of a High Address  1316  cell, and higher than the contents of the associated Low Address  1320  cell, then the incoming PCI Bus Transaction, such as Bus Transaction  1304 , is within the High Address and Low Address cells that are associated with a Virtual Adapter (as indicated by column  1324 ) and the incoming PCI Bus Transaction, such as Bus Transaction  1304 , is allowed to be performed on the matching Virtual Adapter. If the incoming PCI Bus Transaction, such as Bus Transaction  1304 , has an address that is not between the contents of a High Address  1316  cell and the contents of the associated Low Address  1320  cell, then the incoming PCI Bus Transaction, such as Bus Transaction  1304 , must not be allowed to complete. The second mechanism is to simply allow a single entry in the Buffer Table  1390  per Virtual Adapter.  
         [0079]     The third mechanism is to compare the incoming PCI Bus Transaction&#39;s, such as Bus Transaction  1304 , memory address  1308  with each row of Page Starting Address  1322  and with each row of Page Starting Address  1322  plus the page size in the Page Table  1392  as shown by arrow  1314 . If the incoming PCI Bus Transaction, such as Bus Transaction  1304 , has an address that is higher than or equal to the contents of the Page Starting Address  1322  cell and lower the Page Starting Address  1322  cell plus the page size, then the incoming PCI Bus Transaction, such as Bus Transaction  1304 , is within a Page that is associated with a Virtual Adapter (as indicated by column  1326 ) and the incoming PCI Bus Transaction, such as Bus Transaction  1304 , is allowed to be performed on the matching Virtual Adapter. If the incoming PCI Bus Transaction, such as Bus Transaction  1304 , has an address that is not within the range of the Page Starting Address  1322  cell and the Page Starting Address  1322  cell plus the page size, then the incoming PCI Bus Transaction, such as Bus Transaction  1304 , must not be allowed to complete. The fourth mechanism is to simply allow a single entry in the Page Table  1392  per Virtual Adapter.  
         [0080]     With reference next to  FIG. 14 , a functional block diagram of the PCI Family Adapter, such as PCI Family Adapter  1400 , is depicted in accordance with a preferred embodiment of the present invention.  
         [0081]      FIG. 14  depicts several mechanisms for how the Requestor Bus Number, such as Host Bus Number  1408 , Requestor Device Number, such as Host Device Number  1412 , and Requestor Function Number, such as Host Function Number  1416 , referenced in an incoming PCI Bus Transaction, such as Bus Transaction  1404 , can be used to index into either a Buffer Table, such as Buffer Table  1498 , as indicated by arrow  1424 , a Page Table, such as Page Table  1494 , as indicated by arrow  1490 , or an indirect Local Address Table, such as Local Address Table  1464 , as indicated by arrow  1450 . Buffer Table  1498  contains the same contents as Buffer Table  1390  in  FIG. 13 . Page Table  1490  contains the same contents as Page Table  1392  in  FIG. 13 . Local Address Table  1464  contains local PCI Family Adapter memory addresses, such as is shown at  1468 ,  1472  and  1476 , that reference either a Buffer Table, such as Buffer Table  1438 , as indicated by arrow  1484 , or a Page Table, such as Page Table  1434 , as indicated by arrow  1480 , that only contains host memory addresses that are mapped to the same Virtual Adapter.  
         [0082]     Using the Requestor Bus Number, such as Host Bus Number  1408 , Requestor Device Number, such as Host Device Number  1412 , and Requestor Function Number, such as Host Function Number  1416 , referenced in an incoming PCI Bus Transaction, such as Bus Transaction  1404 , provides an additional check beyond the memory address mappings using received address  1420  that were set up by a host LPAR manager.  
         [0083]     Turning next to  FIG. 15 , a Virtual Adapter Level Management Approach is depicted. Under this approach, a physical or virtual host creates one or more Virtual Adapters, such as Virtual Adapter  1   1514 , each containing a set of resources that is within the scope of the Physical Adapter, such as PCI Adapter  1532 . Physical PCI adapter  1532  contains one or more physical PCI ports, such as physical PCI port  1528 , and one or more down stream physical ports, such as Physical Ports  1518  and  1522 . Processing means within the physical PCI adapter  1532  create virtual PCI ports each with their own bus number, device number and function number, such as BDF 1 through BDF N depicted at  1526 . The virtual adapter, such as Virtual Adapter  1   1514 , has a PCI port address, such as  1506 , associated with a given virtual PCI port, such as  1526 , for the physical PCI port, such as PCI Port  1528 . Processing means with the physical PCI adapter  1532  also creates virtual downstream ports, such as VP 1 through VP N for physical down stream port  1518 , depicted at  1516 , and VP 1 through VP N for physical down stream port  1522 , depicted at  1524 . The virtual adapter, such as Virtual Adapter  1   1514 , has a down stream port address, such as  1508  and  1510 , associated with a given virtual down stream port, such as  1516  and  1524 , for each physical port, such as Physical Port  1   1518  and Physical Port  2   1522 . The virtual adapter also has a The set of resources associated with the Virtual Adapter  1   1514  minimally include at least one virtual PCI port, such as BDF 1 in  1526 , for each physical PCI port, such as physical port  1528 ; and one virtual down stream port, such as VP 1 in  1516  and  1524 , for each physical down stream port, such as physical down stream ports  1518  and  1522 . The set of resources associated with the Virtual Adapter  1   1514  may also include: processing queues and associated resources, such as  1504 , and one or more Memory Translation and Protection Tables, such as Address TPT  1511  and Verb Memory TPT  1512 . Thus, each of the virtual adapters, such as virtual adapter  1   1514 , that are created by physical PCI adapter  1532  appears to all logical entries outside of physical PCI adapter  1532  to be totally independent adapters, with their own PCI and down stream addresses.  
         [0084]     Turning next to  FIG. 16 , a Virtual Resource Level Management approach is depicted. Under this approach, a physical or virtual host creates one or more Virtual Resources, such as Virtual Resource  1694  which represents a Processing Queue,  1692  which represents a Virtual PCI Port,  1688  and  1690  which represent a Virtual Downstream Port, and  1675  and  1676  which represent Address Translation and Protection Tables for the PCI bus and verb memory, respectively. Under this approach, the various virtual adapters created by physical PCI adapter  1674  do not have their own PCI bus number, device number and function number, but instead are represented by a subset of the address space of the single bus number, device number, and function number assigned to physical adapter  1674 .  
         [0085]     Turning next to  FIG. 17 , a diagram illustrating an adapter virtualization approach that allows a System Image within a multiple System Image Virtual Server to directly expose a portion, or all, of its associated System Memory to a shared PCI Adapter without having to go through a trusted component, such as a LPAR manager, is depicted. Using the mechanisms described in this document, a System Image is responsible for registering physical memory addresses it wants to expose to a virtual adapter or virtual resource with the LPAR manager. The LPAR manager is responsible for translating physical memory addresses exposed by a System Image into PCI bus addresses used on the PCI bus which equal the real memory addresses used to access memory. The LPAR manager is responsible for setting up the adapter&#39;s PCI Bus Address Translation and Protection Table (ATPT) with these translations and access controls and communicating to the System Image when this process is complete. The System Image is responsible for registering memory, including the physical memory addresses, with the adapter. The adapter&#39;s PCI Bus ATPT is responsible for performing access control on DMA operations in accordance with a preferred embodiment of the present invention. The adapter&#39;s verb memory ATPT is responsible for: associating a resource to one or more PCI virtual ports and to one or more virtual downstream ports; performing the registrations requested by a System Image; and performing the I/O transaction requested by a System Image in accordance with a preferred embodiment of the present invention.  
         [0086]      FIG. 17  depicts a virtual system image, such as System Image A  1796 , which runs in host memory, such as Host Memory  1798 , and has applications running on it. Each application has its own Virtual Address (VA) space, such App 1 VA Space  1792  and  1794 , and App 2 VA Space  1790 . The VA Space is mapped by the OS into a set of physically contiguous physical memory addresses. The LPAR manager maps physical memory addresses to PCI bus addresses used on the PCI bus which equal the real memory addresses used to access memory. In  FIG. 17 , Application 1 VA Space  1794  maps into a portion of Logical Memory Block (LMB)  1   1786  and  2   1784 . Similarly, Application 1 VA Space  1792  maps into a portion of Logical Memory Block (LMB)  3   1782  and  4   1780 . Finally, Application 2 VA Space  1790  maps into a portion of Logical Memory Block (LMB)  4   1780  and N  1778 .  
         [0087]     A System Image, such as System Image A  1796  depicted in  FIG. 17 , does not directly expose the real memory addresses, such as the addresses used by the I/O ASIC, such as I/O ASIC  1768 , used to reference Host Memory  1798 , to the PCI Adapter, such as PCI Adapter  1532  and  1674 . Instead, the host depicted in  FIG. 17  assigns a PCI Bus Address Translation and Protection Table to a System Image and to either: a Virtual Adapter or Virtual Resource; a set of Virtual Adapters and Virtual Resources; or to all Virtual Adapters and Virtual Resources. For example, PCI Bus Address Translation and Protection Table  1511  contains the list of Host real memory addresses associated with System Image A  1796  and Virtual Adapter  1   1514 . Similarly, PCI Bus Address Translation and Protection Table  1675  contains the list of Host real memory addresses associated with System Image A  1796  and the Virtual Resource(s) that are associated with PCI Bus Address Translation and Protection Table  1675 .  
         [0088]     When a PCI Adapter, such as PCI Adapter  1532  and  1674 , processes a data segment referenced by a work queue element on one of its processing queues, it compares the protection domain associated with the processing queue to the protection domain associated with the memory region referenced by the data segment. If the two do not match, the operation ends in an error. If they match, the PCI Adapter, such as PCI Adapter  1532  and  1674 , compares the PCI Bus Address referenced by the data segment through the memory region mapping to the list of PCI Bus Addresses contained in the PCI Bus ATPT. If the PCI Bus Address referenced by the data segment through the memory region mapping is not in the list of PCI Bus Addresses contained in the PCI Bus ATPT, the operation ends in an error. If the PCI Bus Address referenced by the data segment through the memory region mapping is in the list of PCI Bus Addresses contained in the PCI Bus ATPT, the operation proceeds.  
         [0089]      FIG. 17  also depicts two PCI adapters, one that uses a Virtual Adapter Level Management approach, such as PCI Adapter  1532 , and one that uses a Virtual Resource Level Management approach, such as PCI Adapter  1674 .  
         [0090]     In  FIG. 17 , the PCI Adapter  1532  must associate to a host side System Image the following: one set of processing queues; either a Verb Memory Address Translation and Protection Table or one set of Verb Memory Address Translation and Protection Table entries; one downstream virtual port; either a list of PCI Bus memory addresses from a single PCI Bus Address Translation and Protection Table or a PCI Bus Address Translation and Protection Table that is referenced by using the a Virtual Host (PCI) ID, such as the virtual host&#39;s PCI Bus, Device, Function Number; one downstream virtual port; and one upstream Virtual Adapter (PCI) ID (VAID), such as the Bus, Device, Function Number.  
         [0091]      FIG. 18  is a flowchart outlining the functions used to manage the adapter&#39;s address translations and protection tables, such as those shown at  1511  and  1675  of  FIG. 17 .  
         [0092]      FIG. 18  is entered on  1800 , when the LPAR manager, or a LPAR manager appointed intermediary, is invoked to perform an Address Translation and Protection Table (ATPT) operation. A System Image may perform the invocation in order to register physical memory addresses with the host ATPT, adapter ATPT, or both. A system user, through a management user interface, may perform the invocation in order to create, modify, or destroy an adapter instance and associate that adapter with a new or existing System Image. The LPAR manager itself may perform the invocation in order to create, modify, or destroy an adapter instance and associate that adapter with a new or existing System Image as a result of an autonomic computing initiated operation.  
         [0093]     In  1804 , the LPAR manager determines the type of management operation. If the management operation is for the creation, query, modification, or destruction of a Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach, then the next step is  1808 . Otherwise it is a Memory Region (MR) management operation and the next step is  1837 .  
         [0094]     Note, as previously described, a Virtual Adapter consists of: a set of processing queues, one virtual downstream port identifier, one virtual adapter (upstream port) identifier, a PCI Bus Address Translation and Protection Table (ATPT) or a set of PCI Bus Address Translation and Protection Tables (one per virtual host identifier), and either a verb style memory Address Translation and Protection Table or a set of verb style Address Translation and Protection Table entries. The processing queues includes: InfiniBand standard Queue Pairs, iWARP standard Queue Pairs, or analogous Queue Pairs; InfiniBand standard Completion Queues, iWARP standard Completion Queues, or analogous Completion Queues; and InfiniBand standard Asynchronous Event Queues, iWARP standard Asynchronous Event Queues, or analogous Asynchronous Event Queues.  
         [0095]     Also note, as previously described, a Virtual Resource consists of a set of processing queues, which are associated to: a) one virtual downstream port identifier; b) one virtual adapter (upstream port) identifier; c) through a protection domain, either an verb style ATPT or a set of verb style ATPT entries; and c) a list of PCI Bus Addresses that is obtained by looking up PCI Bus Addresses contained in a verb style ATPT and assuring that those PCI Bus Addresses are also contained in the PCI Bus ATPT. Again, the processing queues includes: InfiniBand standard Queue Pairs, iWARP standard Queue Pairs, or analogous Queue Pairs; InfiniBand standard Completion Queues, iWARP standard Completion Queues, or analogous Completion Queues; and InfiniBand standard Asynchronous Event Queues, iWARP standard Asynchronous Event Queues, or analogous Asynchronous Event Queues.  
         [0096]     In  1808 , the LPAR manager determines if the management operation is a query of the attributes associated with a Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach. If it is a query, then the LPAR manager, in  1812 , queries the Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach, and returns the results of the query to the entity that invoked the LPAR manager. Otherwise the next step is  1816 .  
         [0097]     In  1816 , the LPAR manager determines if the management operation is a Create of a Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach. If it is not a Create, then the LPAR manager continues to  1834 . If it is a Create, then the LPAR manager, in  1820 , determines if there are sufficient resources available to perform the creation. If there are sufficient resources, then, in  1824 , the LPAR manager allocates the resource on the adapter and returns the results to the entity that invoked the LPAR manager. If there are not sufficient resources, then, in  1828 , the LPAR manager creates an error record describing the number of resources still available and returns the results to the entity that invoked the LPAR manager. Otherwise the next step is  1824 .  
         [0098]     In  1834 , the LPAR manager determines if the management operation is a Destroy of a Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach. If it is a Destroy, then the LPAR manager, in  1832 , destroys the Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach, and returns the results to the entity that invoked the LPAR manager. Otherwise, in  1836 , the PCI adapter resets the Virtual Adapter, in the case where the PCI adapter uses the Virtual Adapter Management Approach, or a Virtual Processing Queue Resource, in the case where the PCI adapter uses the Virtual Resource Management Approach, and returns the results to the entity that invoked the LPAR manager.  
         [0099]     In  1837 , the LPAR manager translates the addresses passed in by the OS into real memory addresses. If the Memory Region is a user space Memory Region, then the LPAR manager translates the Virtual Address and Length into a set of real memory addresses that are used by hardware to access memory. If the Memory Region is a privileged space Memory Region or a user space Memory Region that&#39;s been translated into physical memory addresses by the System Image, then the LPAR manager translates the set of physical memory addresses, which are used by the System Image to address memory, into a set of real memory addresses that are used by hardware to access memory. It then continues to step  1838 .  
         [0100]     In  1838 , the LPAR manager determines if the Memory Region (MR) is associated with the System Image that invoked the LPAR manager operation. If the Memory Region is a user space Memory Region, the LPAR manager does this by translating the Virtual Address and Length into a set of real memory addresses that are used by hardware to access memory and then checking that those real memory addresses are associated with the System Image that invoked the LPAR manager operation. If the Memory Region is a privileged space Memory Region or a user space Memory Region that&#39;s been translated into physical memory addresses by the System Image, then the LPAR manager does the MR check by translating the set of physical memory addresses, which are used by the System Image to address memory, into a set of real memory addresses that are used by hardware to access memory and then checking that those real memory addresses are associated with the System Image that invoked the LPAR manager operation.  
         [0101]     In  1838 , if the MR is associated with the System Image that invoked the LPAR manager operation, then the LPAR manager continues to step  1842 . Otherwise it continues to step  1858 .  
         [0102]     In  1842 , the LPAR manager determines if the adapter&#39;s PCI Bus Address Translation and Protection Table (ATPT) has enough entries available to contain the real memory addresses that were translated as part of step  1838 . If the adapter&#39;s PCI Bus Address Translation and Protection Table (ATPT) has enough entries available to contain the real memory addresses that were translated as part of step  1838 , then the LPAR manager continues to step  1850 . Otherwise it continues to step  1858 .  
         [0103]     In  1850 , the LPAR manager uses the real memory addresses that resulted from step  1838  to create a set of associated PCI Bus Addresses and loads the real memory address to PCI Bus Address mapping into the adapter&#39;s PCI Bus Address Translation and Protection Table.  
         [0104]     In  1854 , the LPAR manager returns the PCI Bus Addresses that resulted from the mapping of step  1846  to the System Image that invoked the LPAR manager.  
         [0105]     In  1862 , the System Image uses the adapter&#39;s InfiniBand standard, iWARP standard, or analogous verb semantic memory registration mechanism to register the Memory Region using the PCI Bus Addresses to reference the “physical buffers or physical pages” defined by the InfiniBand standard, iWARP standard, or analogous verb semantic memory registration mechanism. During run-time the adapter uses the PCI bus addresses in the adapter&#39;s ATPT for Direct Memory Accesses and the adapter converts these PCI bus addresses into real memory addresses through the adapter&#39;s PCI Bus ATPT.  
         [0106]     In  1858 , the LPAR manager creates an error record describing the number of reason the operation could not be completed, brings down the System Image that attempted the operation.  
         [0107]     In  1870 , the management operation is considered completed.  
         [0108]      FIG. 19  is a flowchart outlining the functions performed at run-time to validate the memory access of an outbound operation on an adapter downstream port in accordance with a preferred embodiment of the present invention.  
         [0109]     In  1900 , the OS builds and adds one or more Work Queue Elements (WQE), containing one or more Data Segments (DSs) that reference a previously registered Memory Region, to a Work Queue (WQ) that is associated with the OS and resides on a PCI Adapter that supports either the Virtual Adapter Level (VAL) Management approach, such as PCI Adapter  1532 , or the Virtual Resource Level (VRL) Management approach, such as PCI Adapter  1674 . The OS code that builds the WQE may be running in either privileged or user space.  
         [0110]     In  1908 , the OS lets the adapter know that it has more work to do by performing a Memory Mapped I/O (MMIO) Write to the doorbell address associated with the WQ. The OS code that performs the MMIO may be running in either privileged or user space.  
         [0111]     In  1916 , the PCI Adapter performs Verb Style Address Translation and Protection Table (ATPT) access control checks on each Data Segment referenced by each WQE. For each check to be deemed successful, the following conditions must all apply: the Protection Domain in the Verb Style ATPT entry associated with the Data Segment must match the Protection Domain associated with the Processing Queue attempting to access that Verb Style ATPT entry; the physical memory address range referenced by the Data Segment must be within the physical memory address range in the Verb Style ATPT entry associated with the Data Segment; and the type of access requested by the WQE must be one of the access types allowed in the Verb Style ATPT entry associated with the Data Segment.  
         [0112]     In  1920 , if all the checks from  1916  were successful, then the PCI Adapter continues to  1921 . Otherwise it continues on to  1936 .  
         [0113]     In  1921 , the PCI Adapter performs PCI Bus Address Translation and Protection Table (ATPT) access control checks on each Data Segment referenced by each WQE. For each check to be deemed successful, the following conditions must all apply: the physical memory address range translated through the Verb Style ATPT from the Data Segment must be associated with the same System Image as the Processing Queue used to submit the WQE containing the Data Segment.  
         [0114]     In  1922 , if all the checks from  1921  were successful, then the PCI Adapter continues to  1924 . Otherwise it continues on to  1936 .  
         [0115]     In  1924  the adapter marks the WQE as valid, and in  1932  the adapter performs all functions associated with the WQE. For each function that requires a transfer on the downstream network, the physical adapter adds the downstream network&#39;s ID that is associated with the virtual adapter, if the VAL approach is used, or virtual resource, if the VRL approach is used. Examples of a downstream network ID, include: N-port ID for Fibre Channel, SCSI Initiator ID for SCSI, or VLAN ID (or MAC Address) for Ethernet. If the WQE requires an upstream transfer, then for each Data Segment referenced by each WQE, the PCI Adapter obtains from the Verb Style ATPT the physical memory addresses associated with the Data Segment and uses the PCI Bus ATPT to translate these physical memory addresses into the PCI Bus Addresses, which equal real memory addresses used by the host hardware to access memory, used for the transfer.  
         [0116]     In  1936 , the adapter creates a Completion Queue Element describing the results of performing the functions associated with the WQE. The results could be all functions were completed successfully or one, or more, of the functions completed in error. In  1944 , if a completion event was requested, then, in  1948  the adapter generates an event for the operation, and completes in  1954 . Otherwise, the adapter completes the operation in  1954 .  
         [0117]     In  1954  the operation is complete.  
         [0118]      FIG. 20  is a flowchart outlining the functions performed at run-time to validate the memory access of an inbound operation on an adapter downstream port in accordance with a preferred embodiment of the present invention.  
         [0119]     In  2000 , the PCI adapter receives a Virtual Address, in the case of InfiniBand, or Tagged Offset, in the case of iWARP, operation on one of its downstream ports.  
         [0120]     In  2016 , the PCI Adapter performs Verb Style Address Translation and Protection Table (ATPT) access control checks on each buffer referenced by the incoming operation. For the check to be deemed successful, the following conditions must all apply: the Protection Domain in the Verb Style ATPT entry referenced in the incoming operation&#39;s R_Key field, in the case of InfiniBand, or STag field, in the case of iWARP, must match the Protection Domain associated with the Processing Queue referenced in the incoming operation; the physical memory address range referenced by the incoming operation must be within the physical memory address range in the Verb Style ATPT entry associated with the incoming operation; and the type of access requested by the WQE must be one of the access types allowed in the Verb Style ATPT entry associated with the incoming operation.  
         [0121]     In  2020 , if all the checks from  2016  were successful, then the PCI Adapter continues to  2021 . Otherwise it continues on to  2036 .  
         [0122]     In  2021 , the PCI Adapter performs PCI Bus Address Translation and Protection Table (ATPT) access control checks on the incoming operation. For the check to be deemed successful, the following condition must apply: the physical memory address range translated through the Verb Style ATPT from the incoming operation&#39;s R_Key field, in the case of InfiniBand, or STag field, in the case of iWARP, must be associated with the same System Image as the Processing Queue referenced by the incoming operation.  
         [0123]     In  2022 , if all the checks from  2021  were successful, then the PCI Adapter continues to  2024 . Otherwise it continues on to  2036 .  
         [0124]     In  2024  the adapter marks the incoming operation as valid, and in  2032  the adapter performs all functions associated with the operation. For each function that requires a transfer on the downstream network, the physical adapter adds the downstream network&#39;s ID that is associated with the virtual adapter, if the VAL approach is used, or virtual resource, if the VRL approach is used. Examples of a downstream network ID, include: N-port ID for Fibre Channel, SCSI Initiator ID for SCSI, or VLAN ID (or MAC Address) for Ethernet. If the incoming operation requires an upstream transfer, then the PCI Adapter obtains from the Verb Style ATPT the physical memory addresses associated with the incoming operation&#39;s R_Key field, in the case of InfiniBand, or STag field, in the case of iWARP, and uses the PCI Bus ATPT to translate these physical memory addresses into the PCI Bus Addresses, which equal real memory addresses used by the host hardware to access memory, used for the transfer.  
         [0125]     In  2036 , the adapter creates an error record describing the check that failed and tears down the connection. The error record could simply be a counter increment. It then continues to  2054 .  
         [0126]     In  2044 , if the downstream port is InfiniBand, the incoming operation is an RDMA Write with Immediate and a completion event was requested by the Consumer, then, in  2048 , the adapter generates an event for the incoming operation, and completes in  2054 . Otherwise, the adapter completes the operation in  2054 .  
         [0127]     In  2054  the incoming operation is complete.  
         [0128]     The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.