[PATCH 3/8] KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out

Paolo Bonzini
2021-10-13T16:56:32Z

Currently emulator_pio_in clears vcpu->arch.pio.count twice if
emulator_pio_in_out performs kernel PIO. Move the clear into
emulator_pio_out where it is actually necessary.

No functional change intended.

Cc: stable@vger.kernel.org
Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 722f5fcf76e1..218877e297e5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6914,10 +6914,8 @@ static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
vcpu->arch.pio.count = count;
vcpu->arch.pio.size = size;

- if (!kernel_pio(vcpu, vcpu->arch.pio_data)) {
- vcpu->arch.pio.count = 0;
+ if (!kernel_pio(vcpu, vcpu->arch.pio_data))
return 1;
- }

vcpu->run->exit_reason = KVM_EXIT_IO;
vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT;
@@ -6963,9 +6961,16 @@ static int emulator_pio_out(struct kvm_vcpu *vcpu, int size,
unsigned short port, const void *val,
unsigned int count)
{
+ int ret;
+
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);
+ ret = emulator_pio_in_out(vcpu, size, port, (void *)val, count, false);
+ if (ret)
+ vcpu->arch.pio.count = 0;
+
+ return ret;
+
}

static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,
--
2.27.0