From 4771450c345dc5e3e3417d82aff62e0d88e7eee6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 5 Feb 2019 13:01:23 -0800 Subject: [PATCH] Revert "KVM: MMU: drop kvm_mmu_zap_mmio_sptes" Revert back to a dedicated (and slower) mechanism for handling the scenario where all MMIO shadow PTEs need to be zapped due to overflowing the MMIO generation number. The MMIO generation scenario is almost literally a one-in-a-million occurrence, i.e. is not a performance sensitive scenario. Restoring kvm_mmu_zap_mmio_sptes() leaves VM teardown as the only user of kvm_mmu_invalidate_zap_all_pages() and paves the way for removing the fast invalidate mechanism altogether. This reverts commit a8eca9dcc656a405a28ffba43f3d86a1ff0eb331. Cc: Xiao Guangrong Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 22 +++++++++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 69daa57b08a7..aeca3fb1cf63 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -319,6 +319,7 @@ struct kvm_mmu_page { struct list_head link; struct hlist_node hash_link; bool unsync; + bool mmio_cached; /* * The following two entries are used to key the shadow page in the diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index b81e2cad0237..d80c1558b23c 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -391,6 +391,8 @@ static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, mask |= (gpa & shadow_nonpresent_or_rsvd_mask) << shadow_nonpresent_or_rsvd_mask_len; + page_header(__pa(sptep))->mmio_cached = true; + trace_mark_mmio_spte(sptep, gfn, access, gen); mmu_spte_set(sptep, mask); } @@ -5942,6 +5944,24 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); } +static void kvm_mmu_zap_mmio_sptes(struct kvm *kvm) +{ + struct kvm_mmu_page *sp, *node; + LIST_HEAD(invalid_list); + + spin_lock(&kvm->mmu_lock); +restart: + list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { + if (!sp->mmio_cached) + continue; + if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list)) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + spin_unlock(&kvm->mmu_lock); +} + void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) { WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); @@ -5963,7 +5983,7 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) */ if (unlikely(gen == 0)) { kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); - kvm_mmu_invalidate_zap_all_pages(kvm); + kvm_mmu_zap_mmio_sptes(kvm); } }