linux-kernel - Re: [PATCH 6/6] KVM: SEV-ES: reuse advance_sev_es_emulated

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Message-ID: <YqJ5OXwAyXvQuC2/@google.com>
Date:   Thu, 9 Jun 2022 22:50:33 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 6/6] KVM: SEV-ES: reuse advance_sev_es_emulated_ins for
 OUT too

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@...hat.com>
> ---
>  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.

>  		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
>