Set the FRED_VIRT_ENABLE bit (bit 4) in the VIRT_EXT field of VMCB to enable
FRED Virtualization for the guest. This enables automatic save/restore of
FRED MSRs.

Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
---

Changes in v2:
- Confined the enabling of vFRED to svm_vcpu_after_set_cpuid() only
  (Sean Christopherson).

---
 arch/x86/include/asm/svm.h | 1 +
 arch/x86/kvm/svm/svm.c     | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index c0f6523e2b2d..f4a9781c1d6c 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -224,6 +224,7 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 
 #define LBR_CTL_ENABLE_MASK BIT_ULL(0)
 #define VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK BIT_ULL(1)
+#define FRED_VIRT_ENABLE_MASK BIT_ULL(4)
 
 #define SVM_INTERRUPT_SHADOW_MASK	BIT_ULL(0)
 #define SVM_GUEST_INTERRUPT_MASK	BIT_ULL(1)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7d411df3dd78..4b270490b2fd 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4540,6 +4540,11 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	if (guest_cpuid_is_intel_compatible(vcpu))
 		guest_cpu_cap_clear(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);

+	if (guest_cpu_cap_has(vcpu, X86_FEATURE_FRED))
+		svm->vmcb->control.virt_ext |= FRED_VIRT_ENABLE_MASK;
+	else
+		svm->vmcb->control.virt_ext &= ~FRED_VIRT_ENABLE_MASK;
+
 	if (sev_guest(vcpu->kvm))
 		sev_vcpu_after_set_cpuid(svm);
 }
-- 
2.43.0