---
 arch/x86/include/asm/kvm_host.h      | 18 ++++++++++++
 arch/x86/include/asm/kvm_vcpu_regs.h | 16 +++++++++++
 arch/x86/kvm/Kconfig                 |  4 +++
 arch/x86/kvm/x86.c                   | 43 ++++++++++++++++++++++++++++
 arch/x86/kvm/x86.h                   | 28 +++++++++++++++++-
 5 files changed, 108 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0b95126505ac..b246a1a96c4e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -220,6 +220,24 @@ enum {
 	VCPU_SREG_GS,
 	VCPU_SREG_TR,
 	VCPU_SREG_LDTR,
+#ifdef CONFIG_KVM_APX
+	VCPU_XREG_R16 = __VCPU_XREG_R16,
+	VCPU_XREG_R17 = __VCPU_XREG_R17,
+	VCPU_XREG_R18 = __VCPU_XREG_R18,
+	VCPU_XREG_R19 = __VCPU_XREG_R19,
+	VCPU_XREG_R20 = __VCPU_XREG_R20,
+	VCPU_XREG_R21 = __VCPU_XREG_R21,
+	VCPU_XREG_R22 = __VCPU_XREG_R22,
+	VCPU_XREG_R23 = __VCPU_XREG_R23,
+	VCPU_XREG_R24 = __VCPU_XREG_R24,
+	VCPU_XREG_R25 = __VCPU_XREG_R25,
+	VCPU_XREG_R26 = __VCPU_XREG_R26,
+	VCPU_XREG_R27 = __VCPU_XREG_R27,
+	VCPU_XREG_R28 = __VCPU_XREG_R28,
+	VCPU_XREG_R29 = __VCPU_XREG_R29,
+	VCPU_XREG_R30 = __VCPU_XREG_R30,
+	VCPU_XREG_R31 = __VCPU_XREG_R31,
+#endif
 };
 
 enum exit_fastpath_completion {
diff --git a/arch/x86/include/asm/kvm_vcpu_regs.h b/arch/x86/include/asm/kvm_vcpu_regs.h
index 1af2cb59233b..dd0cc171f405 100644
--- a/arch/x86/include/asm/kvm_vcpu_regs.h
+++ b/arch/x86/include/asm/kvm_vcpu_regs.h
@@ -20,6 +20,22 @@
 #define __VCPU_REGS_R13 13
 #define __VCPU_REGS_R14 14
 #define __VCPU_REGS_R15 15
+#define __VCPU_XREG_R16 16
+#define __VCPU_XREG_R17 17
+#define __VCPU_XREG_R18 18
+#define __VCPU_XREG_R19 19
+#define __VCPU_XREG_R20 20
+#define __VCPU_XREG_R21 21
+#define __VCPU_XREG_R22 22
+#define __VCPU_XREG_R23 23
+#define __VCPU_XREG_R24 24
+#define __VCPU_XREG_R25 25
+#define __VCPU_XREG_R26 26
+#define __VCPU_XREG_R27 27
+#define __VCPU_XREG_R28 28
+#define __VCPU_XREG_R29 29
+#define __VCPU_XREG_R30 30
+#define __VCPU_XREG_R31 31
 #endif
 
 #endif /* _ASM_X86_KVM_VCPU_REGS_H */
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 801bf9e520db..f27e3f2937f0 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -93,10 +93,14 @@ config KVM_SW_PROTECTED_VM
 
 	  If unsure, say "N".
 
+config KVM_APX
+	bool
+
 config KVM_INTEL
 	tristate "KVM for Intel (and compatible) processors support"
 	depends on KVM && IA32_FEAT_CTL
 	select X86_FRED if X86_64
+	select KVM_APX if X86_64
 	help
 	  Provides support for KVM on processors equipped with Intel's VT
 	  extensions, a.k.a. Virtual Machine Extensions (VMX).
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a03530795707..07119b4597dc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1261,6 +1261,49 @@ static inline u64 kvm_guest_supported_xfd(struct kvm_vcpu *vcpu)
 }
 #endif
 
+#ifdef CONFIG_KVM_APX
+
+static unsigned long kvm_read_egpr(int reg)
+{
+	return 0;
+}
+
+static void kvm_write_egpr(int reg, unsigned long data)
+{
+}
+
+static unsigned long kvm_register_read_ext(struct kvm_vcpu *vcpu, int reg)
+{
+	switch (reg) {
+	case VCPU_REGS_RAX ... VCPU_REGS_R15:
+		return kvm_register_read_raw(vcpu, reg);
+	case VCPU_XREG_R16 ... VCPU_XREG_R31:
+		return kvm_read_egpr(reg);
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_register_read_ext);
+
+static void kvm_register_write_ext(struct kvm_vcpu *vcpu, int reg, unsigned long val)
+{
+	switch (reg) {
+	case VCPU_REGS_RAX ... VCPU_REGS_R15:
+		kvm_register_write_raw(vcpu, reg, val);
+		break;
+	case VCPU_XREG_R16 ... VCPU_XREG_R31:
+		kvm_write_egpr(reg, val);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_register_write_ext);
+
+#endif /* CONFIG_KVM_APX */
+
 int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
 	u64 xcr0 = xcr;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 94d4f07aaaa0..3447790849e7 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -411,6 +411,29 @@ static inline bool vcpu_match_mmio_gpa(struct kvm_vcpu *vcpu, gpa_t gpa)
 	return false;
 }
 
+#ifdef CONFIG_KVM_APX
+
+unsigned long kvm_register_read_ext(struct kvm_vcpu *vcpu, int reg);
+void kvm_register_write_ext(struct kvm_vcpu *vcpu, int reg, unsigned long val);
+
+static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu, int reg)
+{
+	unsigned long val = kvm_register_read_ext(vcpu, reg);
+
+	return is_64_bit_mode(vcpu) ? val : (u32)val;
+}
+
+static inline void kvm_register_write(struct kvm_vcpu *vcpu,
+				      int reg, unsigned long val)
+{
+	if (!is_64_bit_mode(vcpu))
+		val = (u32)val;
+
+	return kvm_register_write_ext(vcpu, reg, val);
+}
+
+#else
+
 static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu, int reg)
 {
 	unsigned long val = kvm_register_read_raw(vcpu, reg);
@@ -419,13 +442,16 @@ static inline unsigned long kvm_register_read(struct kvm_vcpu *vcpu, int reg)
 }
 
 static inline void kvm_register_write(struct kvm_vcpu *vcpu,
-				       int reg, unsigned long val)
+				      int reg, unsigned long val)
 {
 	if (!is_64_bit_mode(vcpu))
 		val = (u32)val;
+
 	return kvm_register_write_raw(vcpu, reg, val);
 }
 
+#endif
+
 static inline bool kvm_check_has_quirk(struct kvm *kvm, u64 quirk)
 {
 	return !(kvm->arch.disabled_quirks & quirk);
-- 
2.51.0