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SubjectRe: [PATCH v6 14/18] KVM: arm64: Support SDEI_EVENT_SIGNAL hypercall
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Hi Oliver,

On 5/1/22 5:32 AM, Oliver Upton wrote:
> On Sun, Apr 03, 2022 at 11:39:07PM +0800, Gavin Shan wrote:
>> This supports SDEI_EVENT_SIGNAL hypercall. It's used by guest
>> to inject event, whose number must be zero to the specified
>> vCPU. As the shared event isn't supported, calling vCPU is
>> assumed to be the target.
>>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>> arch/arm64/kvm/sdei.c | 45 +++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 45 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
>> index ebdbe7810cf0..e1f6ab9800ee 100644
>> --- a/arch/arm64/kvm/sdei.c
>> +++ b/arch/arm64/kvm/sdei.c
>> @@ -455,6 +455,48 @@ static unsigned long hypercall_mask(struct kvm_vcpu *vcpu, bool mask)
>> return ret;
>> }
>>
>> +static unsigned long hypercall_signal(struct kvm_vcpu *vcpu)
>> +{
>> + struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
>> + struct kvm_sdei_event *event;
>> + unsigned int num = smccc_get_arg(vcpu, 1);
>> + unsigned long ret = SDEI_SUCCESS;
>> +
>> + /*
>> + * The event must be the software signaled one, whose number
>> + * is zero.
>> + */
>> + if (!kvm_sdei_is_sw_signaled(num)) {
>> + ret = SDEI_INVALID_PARAMETERS;
>> + goto out;
>> + }
>> +
>> + spin_lock(&vsdei->lock);
>> +
>> + /* Check if the vcpu has been masked */
>> + if (vsdei->masked) {
>> + ret = SDEI_INVALID_PARAMETERS;
>> + goto unlock;
>> + }
>
> You should still be able to signal an event if the vCPU is masked. Just
> means the bit will rot in the pending bitmap until the vCPU is unmasked.
>

Nice point! The event pending state is set if vCPU is masked. However,
it's not becoming active until the vCPU is unmasked :)

Thanks,
Gavin

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