On Wed, Jun 08, 2022, Paolo Bonzini wrote:
> Now that __emulator_pio_in already fills "val" for in-kernel PIO, it
For some reason the "already" confused the heck out of me. I thought it was
referring to a previous patch, which it kind of is, but then I couldn't figure
out the relevance to this patch.
Ah, I know why I got confused, the in-kernel PIO case has nothing to do with the
usage in complete_fast_pio_in(), e.g. complete_fast_pio_in() could be modified to
call complete_emulator_pio_in() directly even without the previous cleanup in
this series.
Can you split this patch in two? It's comically trivial, but it makes the
changelogs much easier to understand.
Use __emulator_pio_in() directly for fast PIO instead of bouncing through
emulator_pio_in() now that __emulator_pio_in() fills "val" when handling
in-kernel PIO. vcpu->arch.pio.count is guaranteed to be '0', so this a
pure nop.
No functional change intended.
and
Use complete_emulator_pio_in() directly when completing fast PIO, there's
no need to bounce through emulator_pio_in() as the comment about ECX
changing doesn't apply to fast PIO, which isn't used for string I/O.
No functional change intended.
> is both simpler and clearer not to use emulator_pio_in.
> Use the appropriate function in kvm_fast_pio_in and complete_fast_pio_in,
> respectively __emulator_pio_in and complete_emulator_pio_in.
>
> emulator_pio_in_emulated is now the last caller of emulator_pio_in.
>
> No functional change intended.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3b641cd2ff6f..aefcc71a7040 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8692,11 +8692,7 @@ static int complete_fast_pio_in(struct kvm_vcpu *vcpu)
> /* For size less than 4 we merge, else we zero extend */
> val = (vcpu->arch.pio.size < 4) ? kvm_rax_read(vcpu) : 0;
>
> - /*
> - * Since vcpu->arch.pio.count == 1 let emulator_pio_in perform
> - * the copy and tracing
> - */
> - emulator_pio_in(vcpu, vcpu->arch.pio.size, vcpu->arch.pio.port, &val, 1);
> + complete_emulator_pio_in(vcpu, &val);
> kvm_rax_write(vcpu, val);
>
> return kvm_skip_emulated_instruction(vcpu);
> @@ -8711,7 +8707,7 @@ 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(vcpu, size, port, &val, 1);
> + ret = __emulator_pio_in(vcpu, size, port, &val, 1);
> if (ret) {
> kvm_rax_write(vcpu, val);
> return ret;
> --
> 2.31.1
>
>
