[PATCH v10 03/28] KVM: VMX: Disable FRED if FRED consistency checks fail

[Sohil Mehta]

From: "Xin Li (Intel)" <xin@xxxxxxxxx>

Do not virtualize FRED if FRED consistency checks fail.

Either on broken hardware, or when run KVM on top of another hypervisor
before the underlying hypervisor implements nested FRED correctly.

Suggested-by: Chao Gao <chao.gao@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
---
v10:
 - Remove the comment about why not check FRED VM-exit controls in
   cpu_has_vmx_fred() (Sean).
 - Remove redundant parentheses (Sean).
---
 arch/x86/kvm/vmx/capabilities.h | 5 +++++
 arch/x86/kvm/vmx/vmx.c          | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 6be818ce27bf..95d22a54f856 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -409,6 +409,11 @@ static inline bool vmx_pebs_supported(void)
 	       !enable_mediated_pmu;
 }
 
+static inline bool cpu_has_vmx_fred(void)
+{
+	return 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 062631e2dd37..2a2218e0983b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8122,6 +8122,9 @@ static __init void vmx_set_cpu_caps(void)
 		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);
 	kvm_caps.supported_perf_cap = vmx_get_perf_capabilities();
-- 
2.43.0