On 6/17/2022 8:15 PM, Shukla, Santosh wrote:
>
>
> On 6/7/2022 6:37 PM, Maxim Levitsky wrote:
>> On Thu, 2022-06-02 at 19:56 +0530, Santosh Shukla wrote:
>>> VMCB intr_ctrl bit12 (V_NMI_MASK) is set by the processor when handling
>>> NMI in guest and is cleared after the NMI is handled. Treat V_NMI_MASK as
>>> read-only in the hypervisor and do not populate set accessors.
>>>
>>> Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
>>> ---
>>> arch/x86/kvm/svm/svm.c | 20 +++++++++++++++++++-
>>> 1 file changed, 19 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>>> index 860f28c668bd..d67a54517d95 100644
>>> --- a/arch/x86/kvm/svm/svm.c
>>> +++ b/arch/x86/kvm/svm/svm.c
>>> @@ -323,6 +323,16 @@ static int is_external_interrupt(u32 info)
>>> return info == (SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR);
>>> }
>>>
>>> +static bool is_vnmi_enabled(struct vmcb *vmcb)
>>> +{
>>> + return vnmi && (vmcb->control.int_ctl & V_NMI_ENABLE);
>>> +}
>>
>> Following Paolo's suggestion I recently removed vgif_enabled(),
>> based on the logic that vgif_enabled == vgif, because
>> we always enable vGIF for L1 as long as 'vgif' module param is set,
>> which is set unless either hardware or user cleared it.
>>
> Yes. In v2, Thanks!.
>
>> Note that here vmcb is the current vmcb, which can be vmcb02,
>> and it might be wrong
>>
>>> +
>>> +static bool is_vnmi_mask_set(struct vmcb *vmcb)
>>> +{
>>> + return !!(vmcb->control.int_ctl & V_NMI_MASK);
>>> +}
>>> +
>>> static u32 svm_get_interrupt_shadow(struct kvm_vcpu *vcpu)
>>> {
>>> struct vcpu_svm *svm = to_svm(vcpu);
>>> @@ -3502,13 +3512,21 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
>>>
>>> static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu)
>>> {
>>> - return !!(vcpu->arch.hflags & HF_NMI_MASK);
>>> + struct vcpu_svm *svm = to_svm(vcpu);
>>> +
>>> + if (is_vnmi_enabled(svm->vmcb))
>>> + return is_vnmi_mask_set(svm->vmcb);
>>> + else
>>> + return !!(vcpu->arch.hflags & HF_NMI_MASK);
>>> }
>>>
>>> static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
>>> {
>>> struct vcpu_svm *svm = to_svm(vcpu);
>>>
>>> + if (is_vnmi_enabled(svm->vmcb))
>>> + return;
>>
>> What if the KVM wants to mask NMI, shoudn't we update the
>> V_NMI_MASK value in int_ctl instead of doing nothing?
>>
V_NMI_MASK is cpu controlled meaning HW sets the mask while processing
event and clears right after processing, so in away its Read-only for hypervisor.
>> Best regards,
>> Maxim Levitsky
>>
>>
>>> +
>>> if (masked) {
>>> vcpu->arch.hflags |= HF_NMI_MASK;
>>> if (!sev_es_guest(vcpu->kvm))
>>
>>
