Messages in this thread Patch in this message | | | Date | Tue, 1 Feb 2022 19:30:23 +0100 | Subject | Re: [PATCH 0/5] KVM: SVM: nSVM: Implement Enlightened MSR-Bitmap for Hyper-V-on-KVM and fix it for KVM-on-Hyper-V | From | Paolo Bonzini <> |
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On 2/1/22 15:31, Vitaly Kuznetsov wrote: > Paolo Bonzini <pbonzini@redhat.com> writes: > >> On 12/20/21 16:21, Vitaly Kuznetsov wrote: >>> Enlightened MSR-Bitmap feature implements a PV protocol for L0 and L1 >>> hypervisors to collaborate and skip unneeded updates to MSR-Bitmap. >>> KVM implements the feature for KVM-on-Hyper-V but it seems there was >>> a flaw in the implementation and the feature may not be fully functional. >>> PATCHes 1-2 fix the problem. The rest of the series implements the same >>> feature for Hyper-V-on-KVM. >>> >>> Vitaly Kuznetsov (5): >>> KVM: SVM: Drop stale comment from >>> svm_hv_vmcb_dirty_nested_enlightenments() >>> KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real >>> KVM: nSVM: Track whether changes in L0 require MSR bitmap for L2 to be >>> rebuilt >>> KVM: x86: Make kvm_hv_hypercall_enabled() static inline >>> KVM: nSVM: Implement Enlightened MSR-Bitmap feature >>> >>> arch/x86/kvm/hyperv.c | 12 +-------- >>> arch/x86/kvm/hyperv.h | 6 ++++- >>> arch/x86/kvm/svm/nested.c | 47 ++++++++++++++++++++++++++++----- >>> arch/x86/kvm/svm/svm.c | 3 ++- >>> arch/x86/kvm/svm/svm.h | 16 +++++++---- >>> arch/x86/kvm/svm/svm_onhyperv.h | 12 +++------ >>> 6 files changed, 63 insertions(+), 33 deletions(-) >>> >> >> Queued 3-5 now, but it would be nice to have some testcases.
Hmm, it fails to compile with CONFIG_HYPERV disabled, and a trivial #if also fails due to an unused goto label. Does this look good to you?
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index e3759a79d39a..a2b5267b3e73 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -173,9 +173,16 @@ void recalc_intercepts(struct vcpu_svm *svm) */ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) { + int i; + + if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) + return true; + + svm->vmcb->control.msrpm_base_pa = __sme_set(__pa(svm->nested.msrpm)); + +#if IS_ENABLED(CONFIG_HYPERV) struct hv_enlightenments *hve = (struct hv_enlightenments *)svm->nested.ctl.reserved_sw; - int i; /* * MSR bitmap update can be skipped when: @@ -185,10 +192,8 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) kvm_hv_hypercall_enabled(&svm->vcpu) && hve->hv_enlightenments_control.msr_bitmap && (svm->nested.ctl.clean & VMCB_HV_NESTED_ENLIGHTENMENTS)) - goto set_msrpm_base_pa; - - if (!(vmcb12_is_intercept(&svm->nested.ctl, INTERCEPT_MSR_PROT))) return true; +#endif for (i = 0; i < MSRPM_OFFSETS; i++) { u32 value, p; @@ -213,10 +216,6 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm) } svm->nested.force_msr_bitmap_recalc = false; - -set_msrpm_base_pa: - svm->vmcb->control.msrpm_base_pa = __sme_set(__pa(svm->nested.msrpm)); - return true; }
Thanks,
Paolo
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