Re: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

[Gavin Shan]

Hi Eric,

On 11/10/21 7:16 PM, Eric Auger wrote:
> On 8/15/21 2:13 AM, Gavin Shan wrote:
> > This supports SDEI_EVENT_CONTEXT hypercall. It's used by the guest
> > to retrieved the original registers (R0 - R17) in its SDEI event
> > handler. Those registers can be corrupted during the SDEI event
> > delivery.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 40 ++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 40 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index b022ce0a202b..b4162efda470 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -270,6 +270,44 @@ static unsigned long kvm_sdei_hypercall_enable(struct kvm_vcpu *vcpu,
> >   	return ret;
> >   }
> >   
> > +static unsigned long kvm_sdei_hypercall_context(struct kvm_vcpu *vcpu)
> > +{
> > +	struct kvm *kvm = vcpu->kvm;
> > +	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> > +	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> > +	struct kvm_sdei_vcpu_regs *regs;
> > +	unsigned long index = smccc_get_arg1(vcpu);
> s/index/param_id to match the spec?

Sure, but "reg_id" seems better here. As the parameter indicates the GPR index
to be fetched on request of the guest kernel.

> > +	unsigned long ret = SDEI_SUCCESS;
> > +
> > +	/* Sanity check */
> > +	if (!(ksdei && vsdei)) {
> > +		ret = SDEI_NOT_SUPPORTED;
> > +		goto out;
> > +	}
> > +
> > +	if (index > ARRAY_SIZE(vsdei->state.critical_regs.regs)) {
> > +		ret = SDEI_INVALID_PARAMETERS;
> > +		goto out;
> > +	}
> I would move the above after regs = and use regs there (although the
> regs ARRAY_SIZE of both is identifical)

Ok.

> > +
> > +	/* Check if the pending event exists */
> > +	spin_lock(&vsdei->lock);
> > +	if (!(vsdei->critical_event || vsdei->normal_event)) {
> > +		ret = SDEI_DENIED;
> > +		goto unlock;
> > +	}
> > +
> > +	/* Fetch the requested register */
> > +	regs = vsdei->critical_event ? &vsdei->state.critical_regs :
> > +				       &vsdei->state.normal_regs;
> > +	ret = regs->regs[index];
> > +
> > +unlock:
> > +	spin_unlock(&vsdei->lock);
> > +out:
> > +	return ret;
> > +}
> > +
> >   int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   {
> >   	u32 func = smccc_get_function(vcpu);
> > @@ -290,6 +328,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> >   		ret = kvm_sdei_hypercall_enable(vcpu, false);
> >   		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
> > +		ret = kvm_sdei_hypercall_context(vcpu);
> > +		break;
> >   	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
> >   	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
> >   	case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:

Thanks,
Gavin