There is no reason to update the shadow pte here because the guest pte
is only changed to dirty state.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

When kvm emulates an invlpg instruction, it can drop a shadow pte, but
leaves the guest tlbs intact.  This can cause memory corruption when
swapping out.

Without this the other cpu can still write to a freed host physical page.
tlb smp flush must happen if rmap_remove is called always before mmu_lock
is released because the VM will take the mmu_lock before it can finally add
the page to the freelist after swapout. mmu notifier makes it safe to flush
the tlb after freeing the page (otherwise it would never be safe) so we can do
a single flush for multiple sptes invalidated.

Cc: stable@kernel.org
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

In the paging_fetch function rmap_remove is called after setting a large
pte to non-present. This causes rmap_remove to not drop the reference to
the large page. The result is a memory leak of that page.

Cc: stable@kernel.org
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Acked-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This actually describes what is going on, rather than alerting the reader
that something strange is going on.
Signed-off-by: NAvi Kivity <avi@redhat.com>

Signed-off-by: NAvi Kivity <avi@redhat.com>

Effectively reverting to the pre walk_shadow() version -- but now
with the reusable for_each().
Signed-off-by: NAvi Kivity <avi@redhat.com>

The invlpg and sync walkers lack knowledge of large host sptes,
descending to non-existant pagetable level.

Stop at directory level in such case.

Fixes SMP Windows XP with hugepages.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

If the guest executes invlpg, peek into the pagetable and attempt to
prepopulate the shadow entry.

Also stop dirty fault updates from interfering with the fork detector.

2% improvement on RHEL3/AIM7.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Skip syncing global pages on cr3 switch (but not on cr4/cr0). This is
important for Linux 32-bit guests with PAE, where the kmap page is
marked as global.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

It is possible for a shadow page to have a parent link
pointing to a freed page. When zapping a high level table,
kvm_mmu_page_unlink_children fails to remove the parent_pte link.
For that to happen, the child must be unreachable via the shadow
tree, which can happen in shadow_walk_entry if the guest pte was
modified in between walk() and fetch(). Remove the parent pte
reference in such case.

Possible cause for oops in bug #2217430.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Allow guest pagetables to go out of sync.  Instead of emulating write
accesses to guest pagetables, or unshadowing them, we un-write-protect
the page table and allow the guest to modify it at will.  We rely on
invlpg executions to synchronize individual ptes, and will synchronize
the entire pagetable on tlb flushes.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

With pages out of sync invlpg needs to be trapped. For now simply nuke
the entry.

Untested on AMD.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Examine guest pagetable and bring the shadow back in sync. Caller is responsible
for local TLB flush before re-entering guest mode.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

It is necessary to flush all TLB's when a large spte entry is
overwritten with a normal page directory pointer.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Convert gfn_to_pfn to use get_user_pages_fast, which can do lockless
pagetable lookups on x86. Kernel compilation on 4-way guest is 3.7%
faster on VMX.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

EPT is 4 level by default in 32pae(48 bits), but the addr parameter
of kvm_shadow_walk->entry() only accept unsigned long as virtual
address, which is 32bit in 32pae. This result in SHADOW_PT_INDEX()
overflow when try to fetch level 4 index.

Fix it by extend kvm_shadow_walk->entry() to accept 64bit addr in
parameter.
Signed-off-by: NSheng Yang <sheng.yang@intel.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Signed-off-by: NAvi Kivity <avi@qumranet.com>

It is not specific to the paging mode, so can be made global (and reusable).
Signed-off-by: NAvi Kivity <avi@qumranet.com>

The shadow code assigns a pte directly in one place, which is nonatomic on
i386 can can cause random memory references.  Fix by using an atomic setter.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Synchronize changes to host virtual addresses which are part of
a KVM memory slot to the KVM shadow mmu.  This allows pte operations
like swapping, page migration, and madvise() to transparently work
with KVM.
Signed-off-by: NAndrea Arcangeli <andrea@qumranet.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Instead of reading each pte individually, read 256 bytes worth of ptes and
batch process them.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Signed-off-by: NAvi Kivity <avi@qumranet.com>

This patch introduces a gfn_to_pfn() function and corresponding functions like
kvm_release_pfn_dirty().  Using these new functions, we can modify the x86
MMU to no longer assume that it can always get a struct page for any given gfn.

We don't want to eliminate gfn_to_page() entirely because a number of places
assume they can do gfn_to_page() and then kmap() the results.  When we support
IO memory, gfn_to_page() will fail for IO pages although gfn_to_pfn() will
succeed.

This does not implement support for avoiding reference counting for reserved
RAM or for IO memory.  However, it should make those things pretty straight
forward.

Since we're only introducing new common symbols, I don't think it will break
the non-x86 architectures but I haven't tested those.  I've tested Intel,
AMD, NPT, and hugetlbfs with Windows and Linux guests.

[avi: fix overflow when shifting left pfns by adding casts]
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Unify slots_lock acquision around vcpu_run(). This is simpler and less
error-prone.

Also fix some callsites that were not grabbing the lock properly.

[avi: drop slots_lock while in guest mode to avoid holding the lock
      for indefinite periods]
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

If we populate a shadow pte due to a fault (and not speculatively due to a
pte write) then we can set the accessed bit on it, as we know it will be
set immediately on the next guest instruction.  This saves a read-modify-write
operation.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Create large pages mappings if the guest PTE's are marked as such and
the underlying memory is hugetlbfs backed.  If the largepage contains
write-protected pages, a large pte is not used.

Gives a consistent 2% improvement for data copies on ram mounted
filesystem, without NPT/EPT.

Anthony measures a 4% improvement on 4-way kernbench, with NPT.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Currently an mmio guest pte is encoded in the shadow pagetable as a
not-present trapping pte, with the SHADOW_IO_MARK bit set.  However
nothing is ever done with this information, so maintaining it is a
useless complication.

This patch moves the check for mmio to before shadow ptes are instantiated,
so the shadow code is never invoked for ptes that reference mmio.  The code
is simpler, and with future work, can be made to handle mmio concurrently.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

A guest partial guest pte write will leave shadow_trap_nonpresent_pte
in spte, which generates a vmexit at the next guest access through that pte.

This patch improves this by reading the full guest pte in advance and thus
being able to update the spte and eliminate the vmexit.

This helps pae guests which use two 32-bit writes to set a single 64-bit pte.

[truncation fix by Eric]
Signed-off-by: NYaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: NFeng (Eric) Liu <eric.e.liu@intel.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

For improved concurrency, the guest walk is performed concurrently with other
vcpus.  This means that we need to revalidate the guest ptes once we have
write-protected the guest page tables, at which point they can no longer be
modified.

The current code attempts to avoid this check if the shadow page table is not
new, on the assumption that if it has existed before, the guest could not have
modified the pte without the shadow lock.  However the assumption is incorrect,
as the racing vcpu could have modified the pte, then instantiated the shadow
page, before our vcpu regains control:

  vcpu0        vcpu1

  fault
  walk pte

               modify pte
               fault in same pagetable
               instantiate shadow page

  lookup shadow page
  conclude it is old
  instantiate spte based on stale guest pte

We could do something clever with generation counters, but a test run by
Marcelo suggests this is unnecessary and we can just do the revalidation
unconditionally.  The pte will be in the processor cache and the check can
be quite fast.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

the cr3 variable is now inside the vcpu->arch structure.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

This patch replaces the mmap_sem lock for the memory slots with a new
kvm private lock, it is needed beacuse untill now there were cases where
kvm accesses user memory while holding the mmap semaphore.
Signed-off-by: NIzik Eidus <izike@qumranet.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Remove the redundant level check when fetching
shadow pte for present & non-present spte.
Signed-off-by: NYaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

If some other cpu steals mmu pages between our check and an attempt to
allocate, we can run out of mmu pages.  Fix by moving the check into the
same critical section as the allocation.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Convert the synchronization of the shadow handling to a separate mmu_lock
spinlock.

Also guard fetch() by mmap_sem in read-mode to protect against alias
and memslot changes.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Since gfn_to_page() is a sleeping function, and we want to make the core mmu
spinlocked, we need to pass the page from the walker context (which can sleep)
to the shadow context (which cannot).

[marcelo: avoid recursive locking of mmap_sem]
Signed-off-by: NAvi Kivity <avi@qumranet.com>

In preparation for a mmu spinlock, add kvm_read_guest_atomic()
and use it in fetch() and prefetch_page().
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Do not hold kvm->lock mutex across the entire pagefault code,
only acquire it in places where it is necessary, such as mmu
hash list, active list, rmap and parent pte handling.

Allow concurrent guest walkers by switching walk_addr() to use
mmap_sem in read-mode.

And get rid of the lockless __gfn_to_page.

[avi: move kvm_mmu_pte_write() locking inside the function]
[avi: add locking for real mode]
[avi: fix cmpxchg locking]
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

This paves the way for multiple architecture support.  Note that while
ioapic.c could potentially be shared with ia64, it is also moved.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Move all the architecture-specific fields in kvm_vcpu into a new struct
kvm_vcpu_arch.
Signed-off-by: NZhang Xiantao <xiantao.zhang@intel.com>
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>