KVM: PPC: Book3S HV: Support POWER6 compatibility mode on POWER7

This enables us to use the Processor Compatibility Register (PCR) on
POWER7 to put the processor into architecture 2.05 compatibility mode
when running a guest.  In this mode the new instructions and registers
that were introduced on POWER7 are disabled in user mode.  This
includes all the VSX facilities plus several other instructions such
as ldbrx, stdbrx, popcntw, popcntd, etc.

To select this mode, we have a new register accessible through the
set/get_one_reg interface, called KVM_REG_PPC_ARCH_COMPAT.  Setting
this to zero gives the full set of capabilities of the processor.
Setting it to one of the "logical" PVR values defined in PAPR puts
the vcpu into the compatibility mode for the corresponding
architecture level.  The supported values are:

0x0f000002	Architecture 2.05 (POWER6)
0x0f000003	Architecture 2.06 (POWER7)
0x0f100003	Architecture 2.06+ (POWER7+)

Since the PCR is per-core, the architecture compatibility level and
the corresponding PCR value are stored in the struct kvmppc_vcore, and
are therefore shared between all vcpus in a virtual core.

Signed-off-by: Paul Mackerras <paulus@samba.org>
[agraf: squash in fix to add missing break statements and documentation]
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S HV: Don't crash host on unknown guest interrupt

If we come out of a guest with an interrupt that we don't know about,
instead of crashing the host with a BUG(), we now return to userspace
with the exit reason set to KVM_EXIT_UNKNOWN and the trap vector in
the hw.hardware_exit_reason field of the kvm_run structure, as is done
on x86.  Note that run->exit_reason is already set to KVM_EXIT_UNKNOWN
at the beginning of kvmppc_handle_exit().

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Fix compilation without CONFIG_ALTIVEC

Commit 9d1ffdd8f3 ("KVM: PPC: Book3S PR: Don't corrupt guest state
when kernel uses VMX") added a call to kvmppc_load_up_altivec() that
isn't guarded by CONFIG_ALTIVEC, causing a link failure when building
a kernel without CONFIG_ALTIVEC set.  This adds an #ifdef to fix this.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Keep volatile reg values in vcpu rather than shadow_vcpu

Currently PR-style KVM keeps the volatile guest register values
(R0 - R13, CR, LR, CTR, XER, PC) in a shadow_vcpu struct rather than
the main kvm_vcpu struct.  For 64-bit, the shadow_vcpu exists in two
places, a kmalloc'd struct and in the PACA, and it gets copied back
and forth in kvmppc_core_vcpu_load/put(), because the real-mode code
can't rely on being able to access the kmalloc'd struct.

This changes the code to copy the volatile values into the shadow_vcpu
as one of the last things done before entering the guest.  Similarly
the values are copied back out of the shadow_vcpu to the kvm_vcpu
immediately after exiting the guest.  We arrange for interrupts to be
still disabled at this point so that we can't get preempted on 64-bit
and end up copying values from the wrong PACA.

This means that the accessor functions in kvm_book3s.h for these
registers are greatly simplified, and are same between PR and HV KVM.
In places where accesses to shadow_vcpu fields are now replaced by
accesses to the kvm_vcpu, we can also remove the svcpu_get/put pairs.
Finally, on 64-bit, we don't need the kmalloc'd struct at all any more.

With this, the time to read the PVR one million times in a loop went
from 567.7ms to 575.5ms (averages of 6 values), an increase of about
1.4% for this worse-case test for guest entries and exits.  The
standard deviation of the measurements is about 11ms, so the
difference is only marginally significant statistically.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Allow guest to use 64k pages

This adds the code to interpret 64k HPTEs in the guest hashed page
table (HPT), 64k SLB entries, and to tell the guest about 64k pages
in kvm_vm_ioctl_get_smmu_info().  Guest 64k pages are still shadowed
by 4k pages.

This also adds another hash table to the four we have already in
book3s_mmu_hpte.c to allow us to find all the PTEs that we have
instantiated that match a given 64k guest page.

The tlbie instruction changed starting with POWER6 to use a bit in
the RB operand to indicate large page invalidations, and to use other
RB bits to indicate the base and actual page sizes and the segment
size.  64k pages came in slightly earlier, with POWER5++.
We use one bit in vcpu->arch.hflags to indicate that the emulated
cpu supports 64k pages, and another to indicate that it has the new
tlbie definition.

The KVM_PPC_GET_SMMU_INFO ioctl presents a bit of a problem, because
the MMU capabilities depend on which CPU model we're emulating, but it
is a VM ioctl not a VCPU ioctl and therefore doesn't get passed a VCPU
fd.  In addition, commonly-used userspace (QEMU) calls it before
setting the PVR for any VCPU.  Therefore, as a best effort we look at
the first vcpu in the VM and return 64k pages or not depending on its
capabilities.  We also make the PVR default to the host PVR on recent
CPUs that support 1TB segments (and therefore multiple page sizes as
well) so that KVM_PPC_GET_SMMU_INFO will include 64k page and 1TB
segment support on those CPUs.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Use 64k host pages where possible

Currently, PR KVM uses 4k pages for the host-side mappings of guest
memory, regardless of the host page size.  When the host page size is
64kB, we might as well use 64k host page mappings for guest mappings
of 64kB and larger pages and for guest real-mode mappings.  However,
the magic page has to remain a 4k page.

To implement this, we first add another flag bit to the guest VSID
values we use, to indicate that this segment is one where host pages
should be mapped using 64k pages.  For segments with this bit set
we set the bits in the shadow SLB entry to indicate a 64k base page
size.  When faulting in host HPTEs for this segment, we make them
64k HPTEs instead of 4k.  We record the pagesize in struct hpte_cache
for use when invalidating the HPTE.

For now we restrict the segment containing the magic page (if any) to
4k pages.  It should be possible to lift this restriction in future
by ensuring that the magic 4k page is appropriately positioned within
a host 64k page.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Handle PP0 page-protection bit in guest HPTEs

64-bit POWER processors have a three-bit field for page protection in
the hashed page table entry (HPTE).  Currently we only interpret the two
bits that were present in older versions of the architecture.  The only
defined combination that has the new bit set is 110, meaning read-only
for supervisor and no access for user mode.

This adds code to kvmppc_mmu_book3s_64_xlate() to interpret the extra
bit appropriately.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Correct errors in H_ENTER implementation

The implementation of H_ENTER in PR KVM has some errors:

* With H_EXACT not set, if the HPTEG is full, we return H_PTEG_FULL
  as the return value of kvmppc_h_pr_enter, but the caller is expecting
  one of the EMULATE_* values.  The H_PTEG_FULL needs to go in the
  guest's R3 instead.

* With H_EXACT set, if the selected HPTE is already valid, the H_ENTER
  call should return a H_PTEG_FULL error.

This fixes these errors and also makes it write only the selected HPTE,
not the whole group, since only the selected HPTE has been modified.
This also micro-optimizes the calculations involving pte_index and i.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Make HPT accesses and updates SMP-safe

This adds a per-VM mutex to provide mutual exclusion between vcpus
for accesses to and updates of the guest hashed page table (HPT).
This also makes the code use single-byte writes to the HPT entry
when updating of the reference (R) and change (C) bits.  The reason
for doing this, rather than writing back the whole HPTE, is that on
non-PAPR virtual machines, the guest OS might be writing to the HPTE
concurrently, and writing back the whole HPTE might conflict with
that.  Also, real hardware does single-byte writes to update R and C.

The new mutex is taken in kvmppc_mmu_book3s_64_xlate() when reading
the HPT and updating R and/or C, and in the PAPR HPT update hcalls
(H_ENTER, H_REMOVE, etc.).  Having the mutex means that we don't need
to use a hypervisor lock bit in the HPT update hcalls, and we don't
need to be careful about the order in which the bytes of the HPTE are
updated by those hcalls.

The other change here is to make emulated TLB invalidations (tlbie)
effective across all vcpus.  To do this we call kvmppc_mmu_pte_vflush
for all vcpus in kvmppc_ppc_book3s_64_tlbie().

For 32-bit, this makes the setting of the accessed and dirty bits use
single-byte writes, and makes tlbie invalidate shadow HPTEs for all
vcpus.

With this, PR KVM can successfully run SMP guests.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Allocate kvm_vcpu structs from kvm_vcpu_cache

This makes PR KVM allocate its kvm_vcpu structs from the kvm_vcpu_cache
rather than having them embedded in the kvmppc_vcpu_book3s struct,
which is allocated with vzalloc.  The reason is to reduce the
differences between PR and HV KVM in order to make is easier to have
them coexist in one kernel binary.

With this, the kvm_vcpu struct has a pointer to the kvmppc_vcpu_book3s
struct.  The pointer to the kvmppc_book3s_shadow_vcpu struct has moved
from the kvmppc_vcpu_book3s struct to the kvm_vcpu struct, and is only
present for 32-bit, since it is only used for 32-bit.

Signed-off-by: Paul Mackerras <paulus@samba.org>
[agraf: squash in compile fix from Aneesh]
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S: Move skip-interrupt handlers to common code

Both PR and HV KVM have separate, identical copies of the
kvmppc_skip_interrupt and kvmppc_skip_Hinterrupt handlers that are
used for the situation where an interrupt happens when loading the
instruction that caused an exit from the guest.  To eliminate this
duplication and make it easier to compile in both PR and HV KVM,
this moves this code to arch/powerpc/kernel/exceptions-64s.S along
with other kernel interrupt handler code.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Better handling of host-side read-only pages

Currently we request write access to all pages that get mapped into the
guest, even if the guest is only loading from the page.  This reduces
the effectiveness of KSM because it means that we unshare every page we
access.  Also, we always set the changed (C) bit in the guest HPTE if
it allows writing, even for a guest load.

This fixes both these problems.  We pass an 'iswrite' flag to the
mmu.xlate() functions and to kvmppc_mmu_map_page() to indicate whether
the access is a load or a store.  The mmu.xlate() functions now only
set C for stores.  kvmppc_gfn_to_pfn() now calls gfn_to_pfn_prot()
instead of gfn_to_pfn() so that it can indicate whether we need write
access to the page, and get back a 'writable' flag to indicate whether
the page is writable or not.  If that 'writable' flag is clear, we then
make the host HPTE read-only even if the guest HPTE allowed writing.

This means that we can get a protection fault when the guest writes to a
page that it has mapped read-write but which is read-only on the host
side (perhaps due to KSM having merged the page).  Thus we now call
kvmppc_handle_pagefault() for protection faults as well as HPTE not found
faults.  In kvmppc_handle_pagefault(), if the access was allowed by the
guest HPTE and we thus need to install a new host HPTE, we then need to
remove the old host HPTE if there is one.  This is done with a new
function, kvmppc_mmu_unmap_page(), which uses kvmppc_mmu_pte_vflush() to
find and remove the old host HPTE.

Since the memslot-related functions require the KVM SRCU read lock to
be held, this adds srcu_read_lock/unlock pairs around the calls to
kvmppc_handle_pagefault().

Finally, this changes kvmppc_mmu_book3s_32_xlate_pte() to not ignore
guest HPTEs that don't permit access, and to return -EPERM for accesses
that are not permitted by the page protections.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Use mmu_notifier_retry() in kvmppc_mmu_map_page()

When the MM code is invalidating a range of pages, it calls the KVM
kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
kvm_unmap_hva_range(), which arranges to flush all the existing host
HPTEs for guest pages.  However, the Linux PTEs for the range being
flushed are still valid at that point.  We are not supposed to establish
any new references to pages in the range until the ...range_end()
notifier gets called.  The PPC-specific KVM code doesn't get any
explicit notification of that; instead, we are supposed to use
mmu_notifier_retry() to test whether we are or have been inside a
range flush notifier pair while we have been getting a page and
instantiating a host HPTE for the page.

This therefore adds a call to mmu_notifier_retry inside
kvmppc_mmu_map_page().  This call is inside a region locked with
kvm->mmu_lock, which is the same lock that is called by the KVM
MMU notifier functions, thus ensuring that no new notification can
proceed while we are in the locked region.  Inside this region we
also create the host HPTE and link the corresponding hpte_cache
structure into the lists used to find it later.  We cannot allocate
the hpte_cache structure inside this locked region because that can
lead to deadlock, so we allocate it outside the region and free it
if we end up not using it.

This also moves the updates of vcpu3s->hpte_cache_count inside the
regions locked with vcpu3s->mmu_lock, and does the increment in
kvmppc_mmu_hpte_cache_map() when the pte is added to the cache
rather than when it is allocated, in order that the hpte_cache_count
is accurate.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Mark pages accessed, and dirty if being written

The mark_page_dirty() function, despite what its name might suggest,
doesn't actually mark the page as dirty as far as the MM subsystem is
concerned.  It merely sets a bit in KVM's map of dirty pages, if
userspace has requested dirty tracking for the relevant memslot.
To tell the MM subsystem that the page is dirty, we have to call
kvm_set_pfn_dirty() (or an equivalent such as SetPageDirty()).

This adds a call to kvm_set_pfn_dirty(), and while we are here, also
adds a call to kvm_set_pfn_accessed() to tell the MM subsystem that
the page has been accessed.  Since we are now using the pfn in
several places, this adds a 'pfn' variable to store it and changes
the places that used hpaddr >> PAGE_SHIFT to use pfn instead, which
is the same thing.

This also changes a use of HPTE_R_PP to PP_RXRX.  Both are 3, but
PP_RXRX is more informative as being the read-only page permission
bit setting.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S PR: Reduce number of shadow PTEs invalidated by MMU notifiers

Currently, whenever any of the MMU notifier callbacks get called, we
invalidate all the shadow PTEs.  This is inefficient because it means
that we typically then get a lot of DSIs and ISIs in the guest to fault
the shadow PTEs back in.  We do this even if the address range being
notified doesn't correspond to guest memory.

This commit adds code to scan the memslot array to find out what range(s)
of guest physical addresses corresponds to the host virtual address range
being affected.  For each such range we flush only the shadow PTEs
for the range, on all cpus.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
kvm: powerpc: book3s hv: Fix vcore leak

add kvmppc_free_vcores() to free the kvmppc_vcore structures
that we allocate for a guest, which are currently being leaked.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S HV: Better handling of exceptions that happen in real mode

When an interrupt or exception happens in the guest that comes to the
host, the CPU goes to hypervisor real mode (MMU off) to handle the
exception but doesn't change the MMU context.  After saving a few
registers, we then clear the "in guest" flag.  If, for any reason,
we get an exception in the real-mode code, that then gets handled
by the normal kernel exception handlers, which turn the MMU on.  This
is disastrous if the MMU is still set to the guest context, since we
end up executing instructions from random places in the guest kernel
with hypervisor privilege.

In order to catch this situation, we define a new value for the "in guest"
flag, KVM_GUEST_MODE_HOST_HV, to indicate that we are in hypervisor real
mode with guest MMU context.  If the "in guest" flag is set to this value,
we branch off to an emergency handler.  For the moment, this just does
a branch to self to stop the CPU from doing anything further.

While we're here, we define another new flag value to indicate that we
are in a HV guest, as distinct from a PR guest.  This will be useful
when we have a kernel that can support both PR and HV guests concurrently.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
powerpc: book3e: _PAGE_LENDIAN must be _PAGE_ENDIAN

For booke3e _PAGE_ENDIAN is not defined. Infact what is defined
is "_PAGE_LENDIAN" which is wrong and that should be _PAGE_ENDIAN.
There are no compilation errors as
arch/powerpc/include/asm/pte-common.h defines _PAGE_ENDIAN to 0
as it is not defined anywhere.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
kvm: powerpc: allow guest control "E" attribute in mas2

"E" bit in MAS2 bit indicates whether the page is accessed
in Little-Endian or Big-Endian byte order.
There is no reason to stop guest setting  "E", so allow him."

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
kvm: powerpc: allow guest control "G" attribute in mas2

"G" bit in MAS2 indicates whether the page is Guarded.
There is no reason to stop guest setting  "G", so allow him.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>