Implement Hyper-V L2 TLB flush for nSVM. The feature needs to be enabled both in extended 'nested controls' in VMCB and VP assist page. According to Hyper-V TLFS, synthetic vmexit to L1 is performed with - HV_SVM_EXITCODE_ENL exit_code. - HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH exit_info_1. Note: VP assist page is cached in 'struct kvm_vcpu_hv' so recalc_intercepts() doesn't need to read from guest's memory. KVM needs to update the case upon each VMRUN and after svm_set_nested_state (svm_get_nested_state_pages()) to handle the case when the guest got migrated while L2 was running. Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> --- arch/x86/kvm/svm/hyperv.c | 7 +++++++ arch/x86/kvm/svm/hyperv.h | 30 ++++++++++++++++++++++++++++++ arch/x86/kvm/svm/nested.c | 36 ++++++++++++++++++++++++++++++++++-- 3 files changed, 71 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/hyperv.c b/arch/x86/kvm/svm/hyperv.c index 911f51021af1..088f6429b24c 100644 --- a/arch/x86/kvm/svm/hyperv.c +++ b/arch/x86/kvm/svm/hyperv.c @@ -8,4 +8,11 @@ void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu) { + struct vcpu_svm *svm = to_svm(vcpu); + + svm->vmcb->control.exit_code = HV_SVM_EXITCODE_ENL; + svm->vmcb->control.exit_code_hi = 0; + svm->vmcb->control.exit_info_1 = HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH; + svm->vmcb->control.exit_info_2 = 0; + nested_svm_vmexit(svm); } diff --git a/arch/x86/kvm/svm/hyperv.h b/arch/x86/kvm/svm/hyperv.h index dd2e393f84a0..7b01722838bf 100644 --- a/arch/x86/kvm/svm/hyperv.h +++ b/arch/x86/kvm/svm/hyperv.h @@ -33,6 +33,9 @@ struct hv_enlightenments { */ #define VMCB_HV_NESTED_ENLIGHTENMENTS VMCB_SW +#define HV_SVM_EXITCODE_ENL 0xF0000000 +#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH (1) + static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); @@ -48,6 +51,33 @@ static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) hv_vcpu->nested.vp_id = hve->hv_vp_id; } +static inline bool nested_svm_hv_update_vp_assist(struct kvm_vcpu *vcpu) +{ + if (!to_hv_vcpu(vcpu)) + return true; + + if (!kvm_hv_assist_page_enabled(vcpu)) + return true; + + return kvm_hv_get_assist_page(vcpu); +} + +static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct hv_enlightenments *hve = + (struct hv_enlightenments *)svm->nested.ctl.reserved_sw; + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); + + if (!hv_vcpu) + return false; + + if (!hve->hv_enlightenments_control.nested_flush_hypercall) + return false; + + return hv_vcpu->vp_assist_page.nested_control.features.directhypercall; +} + void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu); #endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */ diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 28b63663e1d9..369b92aaf1ad 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -171,8 +171,12 @@ void recalc_intercepts(struct vcpu_svm *svm) vmcb_clr_intercept(c, INTERCEPT_VINTR); } - /* We don't want to see VMMCALLs from a nested guest */ - vmcb_clr_intercept(c, INTERCEPT_VMMCALL); + /* + * We want to see VMMCALLs from a nested guest only when Hyper-V L2 TLB + * flush feature is enabled. + */ + if (!nested_svm_l2_tlb_flush_enabled(&svm->vcpu)) + vmcb_clr_intercept(c, INTERCEPT_VMMCALL); for (i = 0; i < MAX_INTERCEPT; i++) c->intercepts[i] |= g->intercepts[i]; @@ -489,6 +493,17 @@ static void nested_save_pending_event_to_vmcb12(struct vcpu_svm *svm, static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu) { + /* + * KVM_REQ_HV_TLB_FLUSH flushes entries from either L1's VP_ID or + * L2's VP_ID upon request from the guest. Make sure we check for + * pending entries for the case when the request got misplaced (e.g. + * a transition from L2->L1 happened while processing L2 TLB flush + * request or vice versa). kvm_hv_vcpu_flush_tlb() will not flush + * anything if there are no requests in the corresponding buffer. + */ + if (to_hv_vcpu(vcpu)) + kvm_make_request(KVM_REQ_HV_TLB_FLUSH, vcpu); + /* * TODO: optimize unconditional TLB flush/MMU sync. A partial list of * things to fix before this can be conditional: @@ -835,6 +850,12 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu) return 1; } + /* This fails when VP assist page is enabled but the supplied GPA is bogus */ + if (!nested_svm_hv_update_vp_assist(vcpu)) { + kvm_inject_gp(vcpu, 0); + return 1; + } + vmcb12_gpa = svm->vmcb->save.rax; ret = kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map); if (ret == -EINVAL) { @@ -1412,6 +1433,7 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu) int nested_svm_exit_special(struct vcpu_svm *svm) { u32 exit_code = svm->vmcb->control.exit_code; + struct kvm_vcpu *vcpu = &svm->vcpu; switch (exit_code) { case SVM_EXIT_INTR: @@ -1430,6 +1452,13 @@ int nested_svm_exit_special(struct vcpu_svm *svm) return NESTED_EXIT_HOST; break; } + case SVM_EXIT_VMMCALL: + /* Hyper-V L2 TLB flush hypercall is handled by L0 */ + if (guest_hv_cpuid_has_l2_tlb_flush(vcpu) && + nested_svm_l2_tlb_flush_enabled(vcpu) && + kvm_hv_is_tlb_flush_hcall(vcpu)) + return NESTED_EXIT_HOST; + break; default: break; } @@ -1710,6 +1739,9 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu) return false; } + if (!nested_svm_hv_update_vp_assist(vcpu)) + return false; + return true; } -- 2.35.3