diff options
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 12 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.c | 6 |
2 files changed, 7 insertions, 11 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 084e6c4d1eaf..d4bb9d60dc59 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -514,9 +514,12 @@ static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) /* Rules for using mmu_spte_update: * Update the state bits, it means the mapped pfn is not changed. * - * Whenever an MMU-writable SPTE is overwritten with a read-only SPTE, remote - * TLBs must be flushed. Otherwise rmap_write_protect will find a read-only - * spte, even though the writable spte might be cached on a CPU's TLB. + * If the MMU-writable flag is cleared, i.e. the SPTE is write-protected for + * write-tracking, remote TLBs must be flushed, even if the SPTE was read-only, + * as KVM allows stale Writable TLB entries to exist. When dirty logging, KVM + * flushes TLBs based on whether or not dirty bitmap/ring entries were reaped, + * not whether or not SPTEs were modified, i.e. only the write-tracking case + * needs to flush at the time the SPTEs is modified, before dropping mmu_lock. * * Returns true if the TLB needs to be flushed */ @@ -533,8 +536,7 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) * we always atomically update it, see the comments in * spte_has_volatile_bits(). */ - if (is_mmu_writable_spte(old_spte) && - !is_writable_pte(new_spte)) + if (is_mmu_writable_spte(old_spte) && !is_mmu_writable_spte(new_spte)) flush = true; /* diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index f1a50a78badb..e5af69a8f101 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -133,12 +133,6 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) */ bool spte_has_volatile_bits(u64 spte) { - /* - * Always atomically update spte if it can be updated - * out of mmu-lock, it can ensure dirty bit is not lost, - * also, it can help us to get a stable is_writable_pte() - * to ensure tlb flush is not missed. - */ if (!is_writable_pte(spte) && is_mmu_writable_spte(spte)) return true; |