KVM: x86: Rename local "ecx" variables to "msr" and "pmc" as appropriate

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.

Link: https://lore.kernel.org/r/20250805202224.1475590-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/x86/kvm/x86.c

@@ -1573,10 +1573,10 @@ 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;
 	}
@@ -2027,23 +2027,23 @@ 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);
@@ -2052,23 +2052,23 @@ 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);