ISCSI: Add support for thin-provisioning via discard/UNMAP and bigger LUNs

Update the configure test for libiscsi support to detect version 1.3
or later.  Version 1.3 of libiscsi provides both READCAPACITY16 as well
as UNMAP commands.

Update the iscsi block layer to use READCAPACITY16 to detect the size of
the LUN instead of READCAPACITY10. This allows support for LUNs larger
than 2TB.

Update to implement bdrv_aio_discard() using the UNMAP command.
This allows us to use thin-provisioned LUNs from TGTD and other iSCSI
targets that support thin-provisioning.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
[squashed in subsequent patch from Ronnie to fix off-by-one in LBA count]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: prevent data transfer overflow

Avoid sending more than 2GB of data, as that can cause overflows
in int32_t variables.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: fix refcounting for reads

Recently introduced FUA support also gave us a use-after-free
of the BlockAcctCookie within a SCSIDiskReq, due to unbalanced
reference counting.

The patch fixes this by making scsi_do_read look like a combination
of scsi_*_complete + scsi_*_data.  It does both a ref (like
scsi_read_data) and an unref (like scsi_flush_complete).

Reported-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: fix WRITE SAME transfer length and direction

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: Specify the xfer direction for UNMAP and ATA_PASSTHROUGH commands

scsi_cmd_xfer_mode() is used to specify the xfer direction for SCSI
commands that come in from the guest.  If the direction is set incorrectly
this will eventually cause QEMU to kernel-panic the guest.

Add UNMAP and ATAPASSTHROUGH as commands that send data to the device.

Without this change, recent kernels will send both UNMAP as well
as ATAPASSTHROUGH commands to any /dev/sg* device, which due to the
incorrect xfer direction very quickly causes the guest kernel to crash.

Example causing a crash without the patch applied:

./x86_64-softmmu/qemu-system-x86_64 -m 1024 -enable-kvm -cdrom linuxmint-12-gnome-dvd-64bit.iso -drive file=/dev/sg4,if=scsi,bus=0,unit=6

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: change "removable" field to host many features

It is pointless to add a uint32_t field for every new feature.
Since we will need a new feature soon, convert accesses to "removable"
to look at bit 0 only.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi-disk: add dpofua property

Linux expects REQ_FUA to be advertised only if WRITE+FUA is faster than
WRITE+SYNCHRONIZE CACHE, so we should not set the DPOFUA bit.  However,
it is useful to have it for testing purposes, so add a qdev property to
set it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: do not report bogus overruns for commands in the 0x00-0x1F range

Interpreting cdb[4] == 0 as a request to transfer 256 blocks is only
needed for READ_6 and WRITE_6.  No other command in that range needs
that special-casing, and the resulting overrun breaks scsi-testsuite's
attempt to use command 2 as a known-invalid command.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: parse 16-byte tape CDBs

The transfer length for these commands is different from the transfer
length of the corresponding disk commands, so parse it specially.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: do not require a minimum allocation length for INQUIRY

The requirements on the INQUIRY buffer size are not in my copy of SPC
(SPC-4 r27) and not observed by LIO.  Rip them out.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: do not require a minimum allocation length for REQUEST SENSE

The requirements on the REQUEST SENSE buffer size are not in my copy of SPC
(SPC-4 r27) and not observed by LIO.  Rip them out.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: set VALID bit to 0 in fixed format sense data

The INFORMATION field (bytes 3..6) is never set by QEMU, so the VALID
bit must be 0.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: remove useless debug messages

Optional inquiry information is declared obsolete in the latest versions
of the standard; invalid CDBs or unsupported VPD pages are supported
can be diagnosed with trace_scsi_inquiry.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: Add assertion for use-after-free errors

The QEMU emulation which is currently used with Raspberry PI images
(qemu-system-arm -M versatilepb ...) accesses memory which was freed.

Valgrind output (extract):

==17857== Invalid write of size 4
==17857==    at 0x24EB06: scsi_req_unref (scsi-bus.c:1273)
==17857==    by 0x24FFAE: scsi_read_complete (scsi-disk.c:277)
==17857==    by 0x152ACC: bdrv_co_em_bh (block.c:3363)
==17857==    by 0x13D49C: qemu_bh_poll (async.c:71)
==17857==    by 0x211A8C: main_loop_wait (main-loop.c:503)
==17857==    by 0x207954: main_loop (vl.c:1555)
==17857==    by 0x20E9C9: main (vl.c:3653)
==17857==  Address 0x1c54383c is 12 bytes inside a block of size 260 free'd
==17857==    at 0x4824B3A: free (vg_replace_malloc.c:366)
==17857==    by 0x20ADFA: free_and_trace (vl.c:2250)
==17857==    by 0x4899FC5: g_free (in /lib/libglib-2.0.so.0.2400.1)
==17857==    by 0x24EB3B: scsi_req_unref (scsi-bus.c:1277)
==17857==    by 0x24F003: scsi_req_complete (scsi-bus.c:1383)
==17857==    by 0x25022A: scsi_read_data (scsi-disk.c:334)
==17857==    by 0x24EB9F: scsi_req_continue (scsi-bus.c:1289)
==17857==    by 0x1C7787: lsi_do_dma (lsi53c895a.c:575)
==17857==    by 0x1C8CDA: lsi_execute_script (lsi53c895a.c:1147)
==17857==    by 0x1C74EA: lsi_resume_script (lsi53c895a.c:510)
==17857==    by 0x1C7ECD: lsi_transfer_data (lsi53c895a.c:746)
==17857==    by 0x24EC90: scsi_req_data (scsi-bus.c:1307)

(There are some more similar messages.)

This patch adds an assertion which also detects those errors:

Calling scsi_req_unref is not allowed when the previous call
of that function has decremented refcount to 0, because in this
case req was freed.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>