Reply-To: Gavin Shan <gshan@redhat.com>
Subject: Re: [PATCH v4 12/21] KVM: arm64: Support SDEI_{PRIVATE, SHARED}_RESET
 hypercall
To:     Eric Auger <eauger@redhat.com>, kvmarm@lists.cs.columbia.edu
Cc:     maz@kernel.org, linux-kernel@vger.kernel.org,
        Jonathan.Cameron@huawei.com, pbonzini@redhat.com, will@kernel.org
References: <20210815001352.81927-1-gshan@redhat.com>
 <20210815001352.81927-13-gshan@redhat.com>
 <a4b91fa5-12b0-afeb-4449-c2acb59e8cd7@redhat.com>
From:   Gavin Shan <gshan@redhat.com>
Message-ID: <d163631c-6e66-f7a1-6eea-3bc000e771ca@redhat.com>
Date:   Wed, 12 Jan 2022 11:01:21 +0800
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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