[PATCH v5 07/20] KVM: VMX: Refactor register index retrieval from exit qualification

["Chang S. Bae" <chang.seok.bae@intel.com>]

Introduce a helper to extract the register index from the VMX exit
qualification field.

In addition to the VMX instruction information field, exit qualification
also encodes a register index. This field will expand into the previously
reserved bit for extended register IDs. This refactoring will simplify
the extended register handling without code duplication.

No functional change intended.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
---
V4 -> V5: Switch the argument and convert DEBUG_REG_ACCESS_REG() (review bot [*])

[*]: locally running Sashiko with gemini-3.1-pro-preview
---
 arch/x86/include/asm/vmx.h | 1 -
 arch/x86/kvm/vmx/nested.c  | 2 +-
 arch/x86/kvm/vmx/vmx.c     | 4 ++--
 arch/x86/kvm/vmx/vmx.h     | 5 +++++
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 30cf48e1c390..5645a84f4fbc 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -454,7 +454,6 @@ enum vmcs_field {
 #define DEBUG_REG_ACCESS_TYPE           0x10    /* 4, direction of access */
 #define TYPE_MOV_TO_DR                  (0 << 4)
 #define TYPE_MOV_FROM_DR                (1 << 4)
-#define DEBUG_REG_ACCESS_REG(eq)        (((eq) >> 8) & 0xf) /* 11:8, general purpose reg. */
 
 
 /*
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index fdec041e95c7..8e0523e40477 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6351,7 +6351,7 @@ static bool nested_vmx_exit_handled_cr(struct kvm_vcpu *vcpu,
 
 	switch ((exit_qualification >> 4) & 3) {
 	case 0: /* mov to cr */
-		reg = (exit_qualification >> 8) & 15;
+		reg = vmx_get_exit_qual_reg(exit_qualification);
 		val = kvm_register_read(vcpu, reg);
 		switch (cr) {
 		case 0:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c49bc6fabae3..e7f968e66bfd 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5692,7 +5692,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
 
 	exit_qualification = vmx_get_exit_qual(vcpu);
 	cr = exit_qualification & 15;
-	reg = (exit_qualification >> 8) & 15;
+	reg = vmx_get_exit_qual_reg(exit_qualification);
 	switch ((exit_qualification >> 4) & 3) {
 	case 0: /* mov to cr */
 		val = kvm_register_read(vcpu, reg);
@@ -5810,7 +5810,7 @@ static int handle_dr(struct kvm_vcpu *vcpu)
 		return 1;
 	}
 
-	reg = DEBUG_REG_ACCESS_REG(exit_qualification);
+	reg = vmx_get_exit_qual_reg(exit_qualification);
 	if (exit_qualification & TYPE_MOV_FROM_DR) {
 		kvm_register_write(vcpu, reg, kvm_get_dr(vcpu, dr));
 		err = 0;
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index acb4d7ac8b0a..f3b0ec7ccb03 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -323,6 +323,11 @@ static __always_inline unsigned long vmx_get_exit_qual(struct kvm_vcpu *vcpu)
 	return vt->exit_qualification;
 }
 
+static inline int vmx_get_exit_qual_reg(unsigned long exit_qualification)
+{
+	return (exit_qualification >> 8) & 0xf;
+}
+
 static __always_inline u32 vmx_get_intr_info(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vt *vt = to_vt(vcpu);
-- 
2.53.0