linux-kernel - [PATCH 2/6] KVM: x86: move all vcpu->arch.pio* setup in emulator_pio_in

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Message-Id: <20220608121253.867333-3-pbonzini@redhat.com>
Date:   Wed,  8 Jun 2022 08:12:49 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     seanjc@...gle.com
Subject: [PATCH 2/6] KVM: x86: move all vcpu->arch.pio* setup in emulator_pio_in_out

For now, this is basically an excuse to add back the void* argument to
the function, while removing some knowledge of vcpu->arch.pio* from
its callers.  The WARN that vcpu->arch.pio.count is zero is also
extended to OUT operations.

We cannot do more as long as we have __emulator_pio_in always followed
by complete_emulator_pio_in, which uses the vcpu->arch.pio* fields.
But after fixing that, it will be possible to only populate the
vcpu->arch.pio* fields on userspace exits.

No functional change intended.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/trace.h |  2 +-
 arch/x86/kvm/x86.c   | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index fd28dd40b813..2877c0e92823 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -154,7 +154,7 @@ TRACE_EVENT(kvm_xen_hypercall,
 
 TRACE_EVENT(kvm_pio,
 	TP_PROTO(unsigned int rw, unsigned int port, unsigned int size,
-		 unsigned int count, void *data),
+		 unsigned int count, const void *data),
 	TP_ARGS(rw, port, size, count, data),
 
 	TP_STRUCT__entry(
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2f9100f2564e..8e1e76d0378b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7416,17 +7416,22 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 }
 
 static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
-			       unsigned short port,
+			       unsigned short port, void *data,
 			       unsigned int count, bool in)
 {
-	void *data = vcpu->arch.pio_data;
 	unsigned i;
 	int r;
 
+	WARN_ON_ONCE(vcpu->arch.pio.count);
 	vcpu->arch.pio.port = port;
 	vcpu->arch.pio.in = in;
 	vcpu->arch.pio.count = count;
 	vcpu->arch.pio.size = size;
+	if (in)
+		memset(vcpu->arch.pio_data, 0, size * count);
+	else
+		memcpy(vcpu->arch.pio_data, data, size * count);
+	data = vcpu->arch.pio_data;
 
 	for (i = 0; i < count; i++) {
 		if (in)
@@ -7454,9 +7459,7 @@ static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
 static int __emulator_pio_in(struct kvm_vcpu *vcpu, int size,
 			     unsigned short port, unsigned int count)
 {
-	WARN_ON(vcpu->arch.pio.count);
-	memset(vcpu->arch.pio_data, 0, size * count);
-	return emulator_pio_in_out(vcpu, size, port, count, true);
+	return emulator_pio_in_out(vcpu, size, port, NULL, count, true);
 }
 
 static void complete_emulator_pio_in(struct kvm_vcpu *vcpu, void *val)
@@ -7505,9 +7508,8 @@ static int emulator_pio_out(struct kvm_vcpu *vcpu, int size,
 {
 	int ret;
 
-	memcpy(vcpu->arch.pio_data, val, size * count);
-	trace_kvm_pio(KVM_PIO_OUT, port, size, count, vcpu->arch.pio_data);
-	ret = emulator_pio_in_out(vcpu, size, port, count, false);
+	trace_kvm_pio(KVM_PIO_OUT, port, size, count, val);
+	ret = emulator_pio_in_out(vcpu, size, port, (void *)val, count, false);
 	if (ret)
                 vcpu->arch.pio.count = 0;
 
-- 
2.31.1