Since kvm_arch_prepare_memory_region() is called right after installing the slot marked invalid, wraparound checking should be there to avoid zapping mmio sptes when mmio generation is still MMIO_MAX_GEN - 1.
Signed-off-by: Takuya Yoshikawa <[email protected]> --- This seems to be the simplest solution for fixing the off-by-one issue we discussed before. arch/x86/kvm/mmu.c | 5 +---- arch/x86/kvm/x86.c | 7 +++++++ 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 0d094da..bf7af1e 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4383,11 +4383,8 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm) /* * The very rare case: if the generation-number is round, * zap all shadow pages. - * - * The max value is MMIO_MAX_GEN - 1 since it is not called - * when mark memslot invalid. */ - if (unlikely(kvm_current_mmio_generation(kvm) >= (MMIO_MAX_GEN - 1))) { + if (unlikely(kvm_current_mmio_generation(kvm) >= MMIO_MAX_GEN)) { printk_ratelimited(KERN_INFO "kvm: zapping shadow pages for mmio generation wraparound\n"); kvm_mmu_invalidate_zap_all_pages(kvm); } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7d71c0f..9ddd4ff 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7046,6 +7046,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, memslot->userspace_addr = userspace_addr; } + /* + * In these cases, slots->generation has been increased for marking the + * slot invalid, so we need wraparound checking here. + */ + if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) + kvm_mmu_invalidate_mmio_sptes(kvm); + return 0; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
