Re: [PATCH v6 06/18] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

[Gavin Shan]

Hi Oliver,

On 4/30/22 11:03 PM, Oliver Upton wrote:
> On Sun, Apr 03, 2022 at 11:38:59PM +0800, Gavin Shan wrote:
> > This supports SDEI_EVENT_CONTEXT hypercall. It's used by the guest
> > to retrieve the registers (x0 - x17) from the interrupted or preempted
> > context in the event handler. The interrupted or preempted context
> > is saved prior to handling the event by executing its handler and
> > restored after that.
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/arm64/kvm/sdei.c | 34 ++++++++++++++++++++++++++++++++++
> >   1 file changed, 34 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> > index 941263578b30..af5d11b8eb2f 100644
> > --- a/arch/arm64/kvm/sdei.c
> > +++ b/arch/arm64/kvm/sdei.c
> > @@ -140,6 +140,37 @@ static unsigned long hypercall_enable(struct kvm_vcpu *vcpu, bool enable)
> >   	return ret;
> >   }
> >   
> > +static unsigned long hypercall_context(struct kvm_vcpu *vcpu)
> > +{
> > +	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> > +	struct kvm_sdei_vcpu_context *context;
> > +	unsigned long param_id = smccc_get_arg(vcpu, 1);
> > +	unsigned long ret = SDEI_SUCCESS;
> > +
> > +	spin_lock(&vsdei->lock);
> > +
> > +	/* Check if we have events are being handled */
> > +	context = &vsdei->context[SDEI_EVENT_PRIORITY_CRITICAL];
> > +	context = context->event ? context : NULL;
> > +	context = context ? : &vsdei->context[SDEI_EVENT_PRIORITY_NORMAL];
> > +	context = context->event ? context : NULL;
> > +	if (!context) {
> > +		ret = SDEI_DENIED;
> > +		goto unlock;
> > +	}
>
> Eek! You'll probably be able to drop all of this and just check the SDEI
> active flag.

Yep, the event's active state will be checked instead in next respin :)

Thanks,
Gavin