From 3f4a812edf5cb0a50e65fbdfafdb3e688da18f16 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 1 Nov 2022 15:54:06 +0100 Subject: [PATCH] KVM: nSVM: hyper-v: Enable L2 TLB flush 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. Reviewed-by: Sean Christopherson Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Message-Id: <20221101145426.251680-29-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/hyperv-tlfs.h | 4 ++++ arch/x86/kvm/hyperv.h | 11 +++++++++++ arch/x86/kvm/svm/hyperv.c | 7 +++++++ arch/x86/kvm/svm/hyperv.h | 15 +++++++++++++++ arch/x86/kvm/svm/nested.c | 35 +++++++++++++++++++++++++++++++++-- 5 files changed, 70 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h index b25c679..e3efaf6 100644 --- a/arch/x86/include/asm/hyperv-tlfs.h +++ b/arch/x86/include/asm/hyperv-tlfs.h @@ -631,6 +631,10 @@ struct hv_vmcb_enlightenments { */ #define HV_VMCB_NESTED_ENLIGHTENMENTS 31 +/* Synthetic VM-Exit */ +#define HV_SVM_EXITCODE_ENL 0xf0000000 +#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH (1) + struct hv_partition_assist_pg { u32 tlb_lock_count; }; diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index 5157622..9f96414 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -198,6 +198,17 @@ static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu) code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX); } +static inline int kvm_hv_verify_vp_assist(struct kvm_vcpu *vcpu) +{ + if (!to_hv_vcpu(vcpu)) + return 0; + + if (!kvm_hv_assist_page_enabled(vcpu)) + return 0; + + return kvm_hv_get_assist_page(vcpu); +} + int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu); #endif diff --git a/arch/x86/kvm/svm/hyperv.c b/arch/x86/kvm/svm/hyperv.c index 911f510..088f642 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 7564bdf..02f4784 100644 --- a/arch/x86/kvm/svm/hyperv.h +++ b/arch/x86/kvm/svm/hyperv.h @@ -25,6 +25,21 @@ 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_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct hv_vmcb_enlightenments *hve = &svm->nested.ctl.hv_enlightenments; + 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 748e4de..bc9cd70 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -150,8 +150,12 @@ 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]; @@ -474,6 +478,15 @@ 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 in the right FIFO upon L1/L2 transition as these + * requests are put by other vCPUs asynchronously. + */ + if (to_hv_vcpu(vcpu) && npt_enabled) + 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: * @@ -824,6 +837,13 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu) return 1; } + /* This fails when VP assist page is enabled but the supplied GPA is bogus */ + ret = kvm_hv_verify_vp_assist(vcpu); + if (ret) { + kvm_inject_gp(vcpu, 0); + return ret; + } + vmcb12_gpa = svm->vmcb->save.rax; ret = kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map); if (ret == -EINVAL) { @@ -1421,6 +1441,7 @@ 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: @@ -1439,6 +1460,13 @@ 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; } @@ -1719,6 +1747,9 @@ static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu) return false; } + if (kvm_hv_verify_vp_assist(vcpu)) + return false; + return true; } -- 2.7.4