From 14c07ad89f4d728a468caaea6a769c018c2b8dd6 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Mon, 8 Oct 2018 21:28:08 +0200 Subject: x86/kvm/mmu: introduce guest_mmu When EPT is used for nested guest we need to re-init MMU as shadow EPT MMU (nested_ept_init_mmu_context() does that). When we return back from L2 to L1 kvm_mmu_reset_context() in nested_vmx_load_cr3() resets MMU back to normal TDP mode. Add a special 'guest_mmu' so we can use separate root caches; the improved hit rate is not very important for single vCPU performance, but it avoids contention on the mmu_lock for many vCPUs. On the nested CPUID benchmark, with 16 vCPUs, an L2->L1->L2 vmexit goes from 42k to 26k cycles. Signed-off-by: Vitaly Kuznetsov Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a0c3992a5e88..02888031d038 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8423,8 +8423,10 @@ static void vmx_disable_shadow_vmcs(struct vcpu_vmx *vmx) vmcs_write64(VMCS_LINK_POINTER, -1ull); } -static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) +static inline void nested_release_vmcs12(struct kvm_vcpu *vcpu) { + struct vcpu_vmx *vmx = to_vmx(vcpu); + if (vmx->nested.current_vmptr == -1ull) return; @@ -8438,10 +8440,12 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) vmx->nested.posted_intr_nv = -1; /* Flush VMCS12 to guest memory */ - kvm_vcpu_write_guest_page(&vmx->vcpu, + kvm_vcpu_write_guest_page(vcpu, vmx->nested.current_vmptr >> PAGE_SHIFT, vmx->nested.cached_vmcs12, 0, VMCS12_SIZE); + kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); + vmx->nested.current_vmptr = -1ull; } @@ -8449,8 +8453,10 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) * Free whatever needs to be freed from vmx->nested when L1 goes down, or * just stops using VMX. */ -static void free_nested(struct vcpu_vmx *vmx) +static void free_nested(struct kvm_vcpu *vcpu) { + struct vcpu_vmx *vmx = to_vmx(vcpu); + if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) return; @@ -8483,6 +8489,8 @@ static void free_nested(struct vcpu_vmx *vmx) vmx->nested.pi_desc = NULL; } + kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); + free_loaded_vmcs(&vmx->nested.vmcs02); } @@ -8491,7 +8499,7 @@ static int handle_vmoff(struct kvm_vcpu *vcpu) { if (!nested_vmx_check_permission(vcpu)) return 1; - free_nested(to_vmx(vcpu)); + free_nested(vcpu); return nested_vmx_succeed(vcpu); } @@ -8517,7 +8525,7 @@ static int handle_vmclear(struct kvm_vcpu *vcpu) VMXERR_VMCLEAR_VMXON_POINTER); if (vmptr == vmx->nested.current_vmptr) - nested_release_vmcs12(vmx); + nested_release_vmcs12(vcpu); kvm_vcpu_write_guest(vcpu, vmptr + offsetof(struct vmcs12, launch_state), @@ -8872,7 +8880,8 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu) VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID); } - nested_release_vmcs12(vmx); + nested_release_vmcs12(vcpu); + /* * Load VMCS12 from guest memory since it is not already * cached. @@ -10928,12 +10937,10 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs) */ static void vmx_free_vcpu_nested(struct kvm_vcpu *vcpu) { - struct vcpu_vmx *vmx = to_vmx(vcpu); - - vcpu_load(vcpu); - vmx_switch_vmcs(vcpu, &vmx->vmcs01); - free_nested(vmx); - vcpu_put(vcpu); + vcpu_load(vcpu); + vmx_switch_vmcs(vcpu, &to_vmx(vcpu)->vmcs01); + free_nested(vcpu); + vcpu_put(vcpu); } static void vmx_free_vcpu(struct kvm_vcpu *vcpu) @@ -11300,6 +11307,7 @@ static void nested_ept_init_mmu_context(struct kvm_vcpu *vcpu) { WARN_ON(mmu_is_nested(vcpu)); + vcpu->arch.mmu = &vcpu->arch.guest_mmu; kvm_init_shadow_ept_mmu(vcpu, to_vmx(vcpu)->nested.msrs.ept_caps & VMX_EPT_EXECUTE_ONLY_BIT, @@ -11315,6 +11323,7 @@ static void nested_ept_init_mmu_context(struct kvm_vcpu *vcpu) static void nested_ept_uninit_mmu_context(struct kvm_vcpu *vcpu) { + vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; } @@ -13731,7 +13740,7 @@ static void vmx_leave_nested(struct kvm_vcpu *vcpu) to_vmx(vcpu)->nested.nested_run_pending = 0; nested_vmx_vmexit(vcpu, -1, 0, 0); } - free_nested(to_vmx(vcpu)); + free_nested(vcpu); } static int vmx_check_intercept(struct kvm_vcpu *vcpu, -- cgit