Simply return from kvm_mmu_pte_write path if no shadow page is write-protected, then we can avoid to walk all shadow pages and hold mmu-lock
Signed-off-by: Xiao Guangrong <[email protected]> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 12 +++++++++++- 2 files changed, 12 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d2ac8e2..d2e5fb8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -442,6 +442,7 @@ struct kvm_arch { unsigned int n_requested_mmu_pages; unsigned int n_max_mmu_pages; atomic_t invlpg_counter; + atomic_t indirect_shadow_pages; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; /* * Hash table of struct kvm_mmu_page. diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 2841805..7e6117dc 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1038,8 +1038,10 @@ static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp) hlist_del(&sp->hash_link); list_del(&sp->link); free_page((unsigned long)sp->spt); - if (!sp->role.direct) + if (!sp->role.direct) { free_page((unsigned long)sp->gfns); + atomic_dec(&kvm->arch.indirect_shadow_pages); + } kmem_cache_free(mmu_page_header_cache, sp); kvm_mod_used_mmu_pages(kvm, -1); } @@ -1536,6 +1538,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, kvm_sync_pages(vcpu, gfn); account_shadowed(vcpu->kvm, gfn); + atomic_inc(&vcpu->kvm->arch.indirect_shadow_pages); } if (shadow_trap_nonpresent_pte != shadow_notrap_nonpresent_pte) vcpu->arch.mmu.prefetch_page(vcpu, sp); @@ -3233,6 +3236,13 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, int level, npte, invlpg_counter, r, flooded = 0; bool remote_flush, local_flush, zap_page; + /* + * If we don't have indirect shadow pages, it means no page is + * write-protected, so we can simply exit. + */ + if (!atomic_read(&vcpu->kvm->arch.indirect_shadow_pages)) + return; + zap_page = remote_flush = local_flush = false; offset = offset_in_page(gpa); -- 1.7.4.4 -- 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
