Rename "ecx" variables in {RD,WR}MSR and RDPMC helpers to "msr" and "pmc"
respectively, in anticipation of adding support for the immediate variants
of RDMSR and WRMSRNS, and to better document what the variables hold
(versus where the data originated).

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5af2c5aed0f2..d3afb875133e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1572,10 +1572,10 @@ EXPORT_SYMBOL_GPL(kvm_get_dr);
 
 int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu)
 {
-	u32 ecx = kvm_rcx_read(vcpu);
+	u32 pmc = kvm_rcx_read(vcpu);
 	u64 data;
 
-	if (kvm_pmu_rdpmc(vcpu, ecx, &data)) {
+	if (kvm_pmu_rdpmc(vcpu, pmc, &data)) {
 		kvm_inject_gp(vcpu, 0);
 		return 1;
 	}
@@ -2026,23 +2026,23 @@ static int kvm_msr_user_space(struct kvm_vcpu *vcpu, u32 index,
 
 int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu)
 {
-	u32 ecx = kvm_rcx_read(vcpu);
+	u32 msr = kvm_rcx_read(vcpu);
 	u64 data;
 	int r;
 
-	r = kvm_get_msr_with_filter(vcpu, ecx, &data);
+	r = kvm_get_msr_with_filter(vcpu, msr, &data);
 
 	if (!r) {
-		trace_kvm_msr_read(ecx, data);
+		trace_kvm_msr_read(msr, data);
 
 		kvm_rax_write(vcpu, data & -1u);
 		kvm_rdx_write(vcpu, (data >> 32) & -1u);
 	} else {
 		/* MSR read failed? See if we should ask user space */
-		if (kvm_msr_user_space(vcpu, ecx, KVM_EXIT_X86_RDMSR, 0,
+		if (kvm_msr_user_space(vcpu, msr, KVM_EXIT_X86_RDMSR, 0,
 				       complete_fast_rdmsr, r))
 			return 0;
-		trace_kvm_msr_read_ex(ecx);
+		trace_kvm_msr_read_ex(msr);
 	}
 
 	return kvm_x86_call(complete_emulated_msr)(vcpu, r);
@@ -2051,23 +2051,23 @@ EXPORT_SYMBOL_GPL(kvm_emulate_rdmsr);
 
 int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
 {
-	u32 ecx = kvm_rcx_read(vcpu);
+	u32 msr = kvm_rcx_read(vcpu);
 	u64 data = kvm_read_edx_eax(vcpu);
 	int r;
 
-	r = kvm_set_msr_with_filter(vcpu, ecx, data);
+	r = kvm_set_msr_with_filter(vcpu, msr, data);
 
 	if (!r) {
-		trace_kvm_msr_write(ecx, data);
+		trace_kvm_msr_write(msr, data);
 	} else {
 		/* MSR write failed? See if we should ask user space */
-		if (kvm_msr_user_space(vcpu, ecx, KVM_EXIT_X86_WRMSR, data,
+		if (kvm_msr_user_space(vcpu, msr, KVM_EXIT_X86_WRMSR, data,
 				       complete_fast_msr_access, r))
 			return 0;
 		/* Signal all other negative errors to userspace */
 		if (r < 0)
 			return r;
-		trace_kvm_msr_write_ex(ecx, data);
+		trace_kvm_msr_write_ex(msr, data);
 	}
 
 	return kvm_x86_call(complete_emulated_msr)(vcpu, r);
-- 
2.50.1.565.gc32cd1483b-goog

On 8/5/2025 1:22 PM, Sean Christopherson wrote:
> Rename "ecx" variables in {RD,WR}MSR and RDPMC helpers to "msr" and "pmc"
> respectively, in anticipation of adding support for the immediate variants
> of RDMSR and WRMSRNS, and to better document what the variables hold
> (versus where the data originated).
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson<seanjc@google.com>

Yeah, this makes the immediate MSR handling changes in the following 
patches prominent.