[PATCH v7 07/20] KVM: VMX: Refactor register index retrieval from exit qualification

[Chang S. Bae]

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@xxxxxxxxx>
---
 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 68835ad9af71..f98e40df5004 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -455,7 +455,6 @@ 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 f05ac3c9aa12..7229934c38bb 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6358,7 +6358,7 @@ 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 bd8505d69420..ee975a1ae42f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5698,7 +5698,7 @@ 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);
@@ -5816,7 +5816,7 @@ 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 92eed58f48ad..863b08478544 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -330,6 +330,11 @@ 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