Messages in this thread | | | Date | Thu, 25 Aug 2022 16:26:13 +0530 | Subject | Re: [PATCHv3 5/8] KVM: SVM: Add VNMI support in inject_nmi | From | "Shukla, Santosh" <> |
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On 8/24/2022 6:26 PM, Maciej S. Szmigiero wrote: > 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. >
For L1 with vnmi disabled case - is_vnmi_enabled()->get_vnmi_vmcb() will return false so the execution path will opt EVTINJ model for re-injection.
Thanks, Santosh
> 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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