Re: [PATCH 6/6] KVM: SEV-ES: reuse advance_sev_es_emulated_ins for OUT too

[Paolo Bonzini]

On 6/10/22 00:50, Sean Christopherson wrote:
> On Wed, Jun 08, 2022, Paolo Bonzini wrote:
> > complete_emulator_pio_in only has to be called by
> > complete_sev_es_emulated_ins now; therefore, all that the function does
> > now is adjust sev_pio_count and sev_pio_data.  Which is the same for
> > both IN and OUT.
> >
> > No functional change intended.
> >
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > ---
> >   arch/x86/kvm/x86.c | 19 +++++++++----------
> >   1 file changed, 9 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index fd4382602f65..a3651aa74ed7 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -13007,6 +13007,12 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes,
> >   }
> >   EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read);
> >   
> > +static void advance_sev_es_emulated_pio(struct kvm_vcpu *vcpu, unsigned count, int size)
> > +{
> > +	vcpu->arch.sev_pio_count -= count;
> > +	vcpu->arch.sev_pio_data += count * size;
> > +}
> > +
> >   static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
> >   			   unsigned int port);
> >   
> > @@ -13030,8 +13036,7 @@ static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
> >   		int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count);
> >   
> >   		/* memcpy done already by emulator_pio_out.  */
> > -		vcpu->arch.sev_pio_count -= count;
> > -		vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size;
> > +		advance_sev_es_emulated_pio(vcpu, count, size);
>
> I think this is a bug fix that should go in a separate patch.  size == vcpu->arch.pio.size
> when kvm_sev_es_outs() is called from complete_sev_es_emulated_outs(), but when
> it's called from kvm_sev_es_string_io() it will hold the size of the previous PIO.

It's not a bugfix for current master, because emulator_pio_out() sets 
vcpu->arch.pio.size = size.

However, it has to be moved before "KVM: x86: wean in-kernel PIO from 
vcpu->arch.pio*" or squashed therein.

Paolo

> >   		if (!ret)
> >   			break;
> >   
> > @@ -13047,12 +13052,6 @@ static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
> >   static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,
> >   			  unsigned int port);
> >   
> > -static void advance_sev_es_emulated_ins(struct kvm_vcpu *vcpu, unsigned count, int size)
> > -{
> > -	vcpu->arch.sev_pio_count -= count;
> > -	vcpu->arch.sev_pio_data += count * size;
> > -}
> > -
> >   static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu)
> >   {
> >   	unsigned count = vcpu->arch.pio.count;
> > @@ -13060,7 +13059,7 @@ static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu)
> >   	int port = vcpu->arch.pio.port;
> >   
> >   	complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data);
> > -	advance_sev_es_emulated_ins(vcpu, count, size);
> > +	advance_sev_es_emulated_pio(vcpu, count, size);
> >   	if (vcpu->arch.sev_pio_count)
> >   		return kvm_sev_es_ins(vcpu, size, port);
> >   	return 1;
> > @@ -13076,7 +13075,7 @@ static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,
> >   			break;
> >   
> >   		/* Emulation done by the kernel.  */
> > -		advance_sev_es_emulated_ins(vcpu, count, size);
> > +		advance_sev_es_emulated_pio(vcpu, count, size);
> >   		if (!vcpu->arch.sev_pio_count)
> >   			return 1;
> >   	}
> > --
> > 2.31.1