linux-kernel - [PATCH 02/13] KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in

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Date:   Fri, 22 Oct 2021 11:36:05 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     mlevitsk@...hat.com, seanjc@...gle.com, stable@...r.kernel.org
Subject: [PATCH 02/13] KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out

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@...r.kernel.org
Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.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 379175b725a1..dff28a4fbb21 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