linux-kernel - [PATCH v2 14/25] KVM: VMX: Disable FRED if FRED consistency checks fail

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Date: Wed,  7 Feb 2024 09:26:34 -0800
From: Xin Li <xin3.li@...el.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Cc: seanjc@...gle.com,
	pbonzini@...hat.com,
	corbet@....net,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	shuah@...nel.org,
	vkuznets@...hat.com,
	peterz@...radead.org,
	ravi.v.shankar@...el.com,
	xin@...or.com
Subject: [PATCH v2 14/25] KVM: VMX: Disable FRED if FRED consistency checks fail

Refuse to virtualize FRED if FRED consistency checks fail.

Suggested-by: Chao Gao <chao.gao@...el.com>
Signed-off-by: Xin Li <xin3.li@...el.com>
---
 arch/x86/kvm/vmx/capabilities.h | 10 ++++++++++
 arch/x86/kvm/vmx/vmx.c          |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index e8f3ad0f79ee..73bf6618c425 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -400,6 +400,16 @@ static inline bool vmx_pebs_supported(void)
 	return boot_cpu_has(X86_FEATURE_PEBS) && kvm_pmu_cap.pebs_ept;
 }
 
+static inline bool cpu_has_vmx_fred(void)
+{
+	return boot_cpu_has(X86_FEATURE_FRED) &&
+		(vmcs_config.basic & VMX_BASIC_NESTED_EXCEPTION) &&
+		(vmcs_config.vmexit_ctrl & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) &&
+		(vmcs_config.secondary_vmexit_ctrl & SECONDARY_VM_EXIT_SAVE_IA32_FRED) &&
+		(vmcs_config.secondary_vmexit_ctrl & SECONDARY_VM_EXIT_LOAD_IA32_FRED) &&
+		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_FRED);
+}
+
 static inline bool cpu_has_notify_vmexit(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1f265d526daf..a484b9ac2400 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8113,6 +8113,8 @@ static __init void vmx_set_cpu_caps(void)
 		kvm_cpu_cap_check_and_set(X86_FEATURE_DS);
 		kvm_cpu_cap_check_and_set(X86_FEATURE_DTES64);
 	}
+	if (!cpu_has_vmx_fred())
+		kvm_cpu_cap_clear(X86_FEATURE_FRED);
 
 	if (!enable_pmu)
 		kvm_cpu_cap_clear(X86_FEATURE_PDCM);
-- 
2.43.0