Messages in this thread | | | Date | Wed, 24 Aug 2022 14:56:57 +0200 | From | "Maciej S. Szmigiero" <> | Subject | Re: [PATCHv3 5/8] KVM: SVM: Add VNMI support in inject_nmi |
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On 24.08.2022 14:13, Shukla, Santosh wrote: > Hi Maciej, > > On 8/11/2022 2:54 AM, Maciej S. Szmigiero wrote: >> On 10.08.2022 08:12, Santosh Shukla wrote: >>> Inject the NMI by setting V_NMI in the VMCB interrupt control. processor >>> will clear V_NMI to acknowledge processing has started and will keep the >>> V_NMI_MASK set until the processor is done with processing the NMI event. >>> >>> Signed-off-by: Santosh Shukla <santosh.shukla@amd.com> >>> --- >>> v3: >>> - Removed WARN_ON check. >>> >>> v2: >>> - Added WARN_ON check for vnmi pending. >>> - use `get_vnmi_vmcb` to get correct vmcb so to inject vnmi. >>> >>> arch/x86/kvm/svm/svm.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c >>> index e260e8cb0c81..8c4098b8a63e 100644 >>> --- a/arch/x86/kvm/svm/svm.c >>> +++ b/arch/x86/kvm/svm/svm.c >>> @@ -3479,7 +3479,14 @@ static void pre_svm_run(struct kvm_vcpu *vcpu) >>> static void svm_inject_nmi(struct kvm_vcpu *vcpu) >>> { >>> struct vcpu_svm *svm = to_svm(vcpu); >>> + struct vmcb *vmcb = NULL; >>> + if (is_vnmi_enabled(svm)) { >> >> I guess this should be "is_vnmi_enabled(svm) && !svm->nmi_l1_to_l2" >> since if nmi_l1_to_l2 is true then the NMI to be injected originally >> comes from L1's VMCB12 EVENTINJ field. >> > > Not sure if I understood the case fully.. so trying to sketch scenario here - > if nmi_l1_to_l2 is true then event is coming from EVTINJ. .which could > be one of following case - > 1) L0 (vnmi enabled) and L1 (vnmi disabled)
As far as I can see in this case: is_vnmi_enabled() returns whether VMCB02's int_ctl has V_NMI_ENABLE bit set.
This field in VMCB02 comes from nested_vmcb02_prepare_control() which in the !nested_vnmi_enabled() case (L1 is not using vNMI) copies these bits from VMCB01: > int_ctl_vmcb01_bits |= (V_NMI_PENDING | V_NMI_ENABLE | V_NMI_MASK);
So in this case (L0 uses vNMI) V_NMI_ENABLE will be set in VMCB01, right?
This bit will then be copied to VMCB02 so re-injection will attempt to use vNMI instead of EVTINJ.
> 2) L0 & L1 both vnmi disabled.
This case is ok.
> > In both cases the vnmi check will fail for L1 and execution path > will fall back to default - right? > > Thanks, > Santosh
Thanks, Maciej
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