From b9f3973ab3a80141a6decc34f4740e6494ca7d51 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Tue, 1 Mar 2022 16:36:46 +0200 Subject: [PATCH] KVM: x86: nSVM: implement nested VMLOAD/VMSAVE This was tested by booting L1,L2,L3 (all Linux) and checking that no VMLOAD/VMSAVE vmexits happened. Signed-off-by: Maxim Levitsky Message-Id: <20220301143650.143749-4-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 35 ++++++++++++++++++++++++++++------- arch/x86/kvm/svm/svm.c | 7 +++++++ arch/x86/kvm/svm/svm.h | 8 +++++++- 3 files changed, 42 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 96bab46..d736ec6 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -121,6 +121,20 @@ static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu) vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; } +static bool nested_vmcb_needs_vls_intercept(struct vcpu_svm *svm) +{ + if (!svm->v_vmload_vmsave_enabled) + return true; + + if (!nested_npt_enabled(svm)) + return true; + + if (!(svm->nested.ctl.virt_ext & VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK)) + return true; + + return false; +} + void recalc_intercepts(struct vcpu_svm *svm) { struct vmcb_control_area *c, *h; @@ -162,8 +176,17 @@ void recalc_intercepts(struct vcpu_svm *svm) if (!intercept_smi) vmcb_clr_intercept(c, INTERCEPT_SMI); - vmcb_set_intercept(c, INTERCEPT_VMLOAD); - vmcb_set_intercept(c, INTERCEPT_VMSAVE); + if (nested_vmcb_needs_vls_intercept(svm)) { + /* + * If the virtual VMLOAD/VMSAVE is not enabled for the L2, + * we must intercept these instructions to correctly + * emulate them in case L1 doesn't intercept them. + */ + vmcb_set_intercept(c, INTERCEPT_VMLOAD); + vmcb_set_intercept(c, INTERCEPT_VMSAVE); + } else { + WARN_ON(!(c->virt_ext & VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK)); + } } /* @@ -454,11 +477,6 @@ static void nested_save_pending_event_to_vmcb12(struct vcpu_svm *svm, vmcb12->control.exit_int_info = exit_int_info; } -static inline bool nested_npt_enabled(struct vcpu_svm *svm) -{ - return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE; -} - static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu) { /* @@ -621,6 +639,9 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) svm->vmcb->control.event_inj = svm->nested.ctl.event_inj; svm->vmcb->control.event_inj_err = svm->nested.ctl.event_inj_err; + if (!nested_vmcb_needs_vls_intercept(svm)) + svm->vmcb->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK; + nested_svm_transition_tlb_flush(vcpu); /* Enter Guest-Mode */ diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bd4c64b..af17061 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -960,6 +960,8 @@ static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu) set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SYSENTER_EIP, 0, 0); set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SYSENTER_ESP, 0, 0); + + svm->v_vmload_vmsave_enabled = false; } else { /* * If hardware supports Virtual VMLOAD VMSAVE then enable it @@ -3947,6 +3949,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) svm->tsc_scaling_enabled = tsc_scaling && guest_cpuid_has(vcpu, X86_FEATURE_TSCRATEMSR); + svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD); + svm_recalc_instruction_intercepts(vcpu, svm); /* For sev guests, the memory encryption bit is not reserved in CR3. */ @@ -4695,6 +4699,9 @@ static __init void svm_set_cpu_caps(void) if (tsc_scaling) kvm_cpu_cap_set(X86_FEATURE_TSCRATEMSR); + if (vls) + kvm_cpu_cap_set(X86_FEATURE_V_VMSAVE_VMLOAD); + /* Nested VM can receive #VMEXIT instead of triggering #GP */ kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK); } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index f77a7d2..468f149 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -231,9 +231,10 @@ struct vcpu_svm { unsigned int3_injected; unsigned long int3_rip; - /* cached guest cpuid flags for faster access */ + /* optional nested SVM features that are enabled for this guest */ bool nrips_enabled : 1; bool tsc_scaling_enabled : 1; + bool v_vmload_vmsave_enabled : 1; u32 ldr_reg; u32 dfr_reg; @@ -481,6 +482,11 @@ static inline bool gif_set(struct vcpu_svm *svm) return !!(svm->vcpu.arch.hflags & HF_GIF_MASK); } +static inline bool nested_npt_enabled(struct vcpu_svm *svm) +{ + return svm->nested.ctl.nested_ctl & SVM_NESTED_CTL_NP_ENABLE; +} + /* svm.c */ #define MSR_INVALID 0xffffffffU -- 2.7.4