Commit e1359e2b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini

KVM: x86/mmu: Detect MMIO generation wrap in any address space

The check to detect a wrap of the MMIO generation explicitly looks for a
generation number of zero.  Now that unique memslots generation numbers
are assigned to each address space, only address space 0 will get a
generation number of exactly zero when wrapping.  E.g. when address
space 1 goes from 0x7fffe to 0x80002, the MMIO generation number will
wrap to 0x2.  Adjust the MMIO generation to strip the address space
modifier prior to checking for a wrap.

Fixes: 4bd518f1 ("KVM: use separate generations for each address space")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 15248258
...@@ -5895,11 +5895,28 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) ...@@ -5895,11 +5895,28 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
{ {
gen &= MMIO_GEN_MASK;
/*
* Shift to eliminate the "update in-progress" flag, which isn't
* included in the spte's generation number.
*/
gen >>= 1;
/*
* Generation numbers are incremented in multiples of the number of
* address spaces in order to provide unique generations across all
* address spaces. Strip what is effectively the address space
* modifier prior to checking for a wrap of the MMIO generation so
* that a wrap in any address space is detected.
*/
gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1);
/* /*
* The very rare case: if the generation-number is round, * The very rare case: if the MMIO generation number has wrapped,
* zap all shadow pages. * zap all shadow pages.
*/ */
if (unlikely((gen & MMIO_GEN_MASK) == 0)) { if (unlikely(gen == 0)) {
kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n");
kvm_mmu_invalidate_zap_all_pages(kvm); kvm_mmu_invalidate_zap_all_pages(kvm);
} }
......
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