KVM: x86: Avoid zapping mmio sptes twice for generation wraparound

Now that kvm_arch_memslots_updated() catches every increment of the
memslots->generation, checking if the mmio generation has reached its
maximum value is enough.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9e9285ae9b94..3a9493ad1066 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4390,11 +4390,8 @@ 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);
         }