[PATCH v4 03/20] KVM:x86: Report XSS as to-be-saved if there are supported features

[Yang Weijiang <weijiang.yang@intel.com>]

From: Sean Christopherson <sean.j.christopherson@intel.com>

Add MSR_IA32_XSS to the list of MSRs reported to userspace if
supported_xss is non-zero, i.e. KVM supports at least one XSS
based feature.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 arch/x86/kvm/x86.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 439312e04384..4597ab3c811c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1451,6 +1451,7 @@ static const u32 msrs_to_save_base[] = {
 	MSR_IA32_UMWAIT_CONTROL,
 
 	MSR_IA32_XFD, MSR_IA32_XFD_ERR,
+	MSR_IA32_XSS,
 };
 
 static const u32 msrs_to_save_pmu[] = {
@@ -7173,6 +7174,10 @@ static void kvm_probe_msr_to_save(u32 msr_index)
 		if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR))
 			return;
 		break;
+	case MSR_IA32_XSS:
+		if (!kvm_caps.supported_xss)
+			return;
+		break;
 	default:
 		break;
 	}
-- 
2.27.0