linux-kernel - Re: [PATCH v2 01/13] KVM: x86: Refactor I/O emulation helpers to provide vcpu-only variant

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Message-ID: <87h7zdjs4s.fsf@vitty.brq.redhat.com>
Date:   Wed, 26 Feb 2020 16:16:35 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/13] KVM: x86: Refactor I/O emulation helpers to provide vcpu-only variant

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Add variants of the I/O helpers that take a vCPU instead of an emulation
> context.  This will eventually allow KVM to limit use of the emulation
> context to the full emulation path.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/x86.c | 39 ++++++++++++++++++++++++---------------
>  1 file changed, 24 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fbabb2f06273..6554abef631f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5959,11 +5959,9 @@ static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
>  	return 0;
>  }
>  
> -static int emulator_pio_in_emulated(struct x86_emulate_ctxt *ctxt,
> -				    int size, unsigned short port, void *val,
> -				    unsigned int count)
> +static int emulator_pio_in(struct kvm_vcpu *vcpu, int size,
> +			   unsigned short port, void *val, unsigned int count)
>  {
> -	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
>  	int ret;
>  
>  	if (vcpu->arch.pio.count)
> @@ -5983,17 +5981,30 @@ static int emulator_pio_in_emulated(struct x86_emulate_ctxt *ctxt,
>  	return 0;
>  }
>  
> -static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,
> -				     int size, unsigned short port,
> -				     const void *val, unsigned int count)
> +static int emulator_pio_in_emulated(struct x86_emulate_ctxt *ctxt,
> +				    int size, unsigned short port, void *val,
> +				    unsigned int count)
>  {
> -	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> +	return emulator_pio_in(emul_to_vcpu(ctxt), size, port, val, count);
>  
> +}
> +
> +static int emulator_pio_out(struct kvm_vcpu *vcpu, int size,
> +			    unsigned short port, const void *val,
> +			    unsigned int count)
> +{
>  	memcpy(vcpu->arch.pio_data, val, size * count);
>  	trace_kvm_pio(KVM_PIO_OUT, port, size, count, vcpu->arch.pio_data);
>  	return emulator_pio_in_out(vcpu, size, port, (void *)val, count, false);
>  }
>  
> +static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,
> +				     int size, unsigned short port,
> +				     const void *val, unsigned int count)
> +{
> +	return emulator_pio_out(emul_to_vcpu(ctxt), size, port, val, count);
> +}
> +
>  static unsigned long get_segment_base(struct kvm_vcpu *vcpu, int seg)
>  {
>  	return kvm_x86_ops->get_segment_base(vcpu, seg);
> @@ -6930,8 +6941,8 @@ static int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size,
>  			    unsigned short port)
>  {
>  	unsigned long val = kvm_rax_read(vcpu);
> -	int ret = emulator_pio_out_emulated(&vcpu->arch.emulate_ctxt,
> -					    size, port, &val, 1);
> +	int ret = emulator_pio_out(vcpu, size, port, &val, 1);
> +
>  	if (ret)
>  		return ret;
>  
> @@ -6967,11 +6978,10 @@ static int complete_fast_pio_in(struct kvm_vcpu *vcpu)
>  	val = (vcpu->arch.pio.size < 4) ? kvm_rax_read(vcpu) : 0;
>  
>  	/*
> -	 * Since vcpu->arch.pio.count == 1 let emulator_pio_in_emulated perform
> +	 * Since vcpu->arch.pio.count == 1 let emulator_pio_in perform
>  	 * the copy and tracing
>  	 */
> -	emulator_pio_in_emulated(&vcpu->arch.emulate_ctxt, vcpu->arch.pio.size,
> -				 vcpu->arch.pio.port, &val, 1);
> +	emulator_pio_in(vcpu, vcpu->arch.pio.size, vcpu->arch.pio.port, &val, 1);
>  	kvm_rax_write(vcpu, val);
>  
>  	return kvm_skip_emulated_instruction(vcpu);
> @@ -6986,8 +6996,7 @@ static int kvm_fast_pio_in(struct kvm_vcpu *vcpu, int size,
>  	/* For size less than 4 we merge, else we zero extend */
>  	val = (size < 4) ? kvm_rax_read(vcpu) : 0;
>  
> -	ret = emulator_pio_in_emulated(&vcpu->arch.emulate_ctxt, size, port,
> -				       &val, 1);
> +	ret = emulator_pio_in(vcpu, size, port, &val, 1);
>  	if (ret) {
>  		kvm_rax_write(vcpu, val);
>  		return ret;

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly