From 169577c8840e4da46eac5823fba76899294ac562 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 13 Oct 2021 12:29:42 -0400
Subject: [PATCH] KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out
Git-commit: 0d33b1baeb6ca7165d5ed4fdd1a8f969985e35b9
Patch-mainline: v5.15-rc7
References: stable-5.14.15

commit 0d33b1baeb6ca7165d5ed4fdd1a8f969985e35b9 upstream.

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")
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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 84de77cc6452..244eaa33a1d0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6915,10 +6915,8 @@ 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;
@@ -6964,9 +6962,16 @@ 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,
-- 
2.26.2