Re: [PATCH v4 12/21] KVM: arm64: Support SDEI_{PRIVATE, SHARED}_RESET hypercall

Gavin Shan
2022-01-12T03:01:39Z

Hi Eric,

On 11/10/21 4:37 AM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
>> This supports SDEI_{PRIVATE, SHARED}_RESET. They are used by the
>> guest to purge the private or shared SDEI events, which are registered
> to reset all private SDEI event registrations of the calling PE (resp.
> PRIVATE or SHARED)

Ok.

>> previously.
>>
>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>> arch/arm64/kvm/sdei.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
>> index 3fb33258b494..62efee2b67b8 100644
>> --- a/arch/arm64/kvm/sdei.c
>> +++ b/arch/arm64/kvm/sdei.c
>> @@ -582,6 +582,29 @@ static unsigned long kvm_sdei_hypercall_mask(struct kvm_vcpu *vcpu,
>> return ret;
>> }
>>
>> +static unsigned long kvm_sdei_hypercall_reset(struct kvm_vcpu *vcpu,
>> + bool private)
>> +{
>> + struct kvm *kvm = vcpu->kvm;
>> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
>> + struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
>> + unsigned int mask = private ? (1 << SDEI_EVENT_TYPE_PRIVATE) :
>> + (1 << SDEI_EVENT_TYPE_SHARED);
>> + unsigned long ret = SDEI_SUCCESS;
>> +
>> + /* Sanity check */
>> + if (!(ksdei && vsdei)) {
>> + ret = SDEI_NOT_SUPPORTED;
>> + goto out;
>> + }
>> +
>> + spin_lock(&ksdei->lock);
>> + kvm_sdei_remove_kvm_events(kvm, mask, false);
> With kvm_sdei_remove_kvm_events() implementation, why do you make sure
> that events which have a running handler get unregistered once the
> handler completes? I just see the refcount check that prevents the "KVM
> event object" from being removed.

Good point. I think here we need enhancement to cancel the pending
events prior to destroying them. I will think about it :)

>> + spin_unlock(&ksdei->lock);
>> +out:
>> + return ret;
>> +}
>> +
>> int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>> {
>> u32 func = smccc_get_function(vcpu);
>> @@ -626,8 +649,14 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
>> break;
>> case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:
>> case SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE:
>> + ret = SDEI_NOT_SUPPORTED;
>> + break;
>> case SDEI_1_0_FN_SDEI_PRIVATE_RESET:
>> + ret = kvm_sdei_hypercall_reset(vcpu, true);
>> + break;
>> case SDEI_1_0_FN_SDEI_SHARED_RESET:
>> + ret = kvm_sdei_hypercall_reset(vcpu, false);
>> + break;
>> default:
>> ret = SDEI_NOT_SUPPORTED;
>> }
>>

Thanks,
Gavin