diff mbox series

[v9,12/27] KVM: x86: Report XSS as to-be-saved if there are supported features

Message ID 20240124024200.102792-13-weijiang.yang@intel.com (mailing list archive)
State New, archived
Headers show
Series Enable CET Virtualization | expand

Commit Message

Yang, Weijiang Jan. 24, 2024, 2:41 a.m. UTC 
From: Sean Christopherson <seanjc@google.com>

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

Before enabling CET virtualization series, guest IA32_MSR_XSS is
guaranteed to be 0, i.e., XSAVES/XRSTORS is executed in non-root mode
with XSS == 0, which equals to the effect of XSAVE/XRSTOR.

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

Comments

Chao Gao Jan. 25, 2024, 10:37 a.m. UTC | #1 
On Tue, Jan 23, 2024 at 06:41:45PM -0800, Yang Weijiang wrote:
>From: Sean Christopherson <seanjc@google.com>
>
>Add MSR_IA32_XSS to list of MSRs reported to userspace if supported_xss
>is non-zero, i.e. KVM supports at least one XSS based feature.
>
>Before enabling CET virtualization series, guest IA32_MSR_XSS is
>guaranteed to be 0, i.e., XSAVES/XRSTORS is executed in non-root mode
>with XSS == 0, which equals to the effect of XSAVE/XRSTOR.
>
>Signed-off-by: Sean Christopherson <seanjc@google.com>
>Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Reviewed-by: Chao Gao <chao.gao@intel.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 594c9e025f95..b3a39886e418 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1464,6 +1464,7 @@  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[] = {
@@ -7374,6 +7375,10 @@  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;
 	}