Commit 6a11c860 authored Sep 19, 2025 by Yang Weijiang Committed by Sean Christopherson Sep 23, 2025

KVM: x86: Report KVM supported CET MSRs as to-be-saved



Add CET MSRs to the list of MSRs reported to userspace if the feature,
i.e. IBT or SHSTK, associated with the MSRs is supported by KVM.

Suggested-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-12-seanjc@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>

parent 586ef9dc

arch/x86/kvm/x86.c

+18 −0

Original line number	Diff line number	Diff line
		@@ -344,6 +344,10 @@ static const u32 msrs_to_save_base[] = {
		MSR_IA32_UMWAIT_CONTROL,

		MSR_IA32_XFD, MSR_IA32_XFD_ERR, MSR_IA32_XSS,

		MSR_IA32_U_CET, MSR_IA32_S_CET,
		MSR_IA32_PL0_SSP, MSR_IA32_PL1_SSP, MSR_IA32_PL2_SSP,
		MSR_IA32_PL3_SSP, MSR_IA32_INT_SSP_TAB,
		};

		static const u32 msrs_to_save_pmu[] = {
		@@ -7603,6 +7607,20 @@ static void kvm_probe_msr_to_save(u32 msr_index)
		if (!kvm_caps.supported_xss)
		return;
		break;
		case MSR_IA32_U_CET:
		case MSR_IA32_S_CET:
		if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK) &&
		!kvm_cpu_cap_has(X86_FEATURE_IBT))
		return;
		break;
		case MSR_IA32_INT_SSP_TAB:
		if (!kvm_cpu_cap_has(X86_FEATURE_LM))
		return;
		fallthrough;
		case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP:
		if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK))
		return;
		break;
		default:
		break;
		}