KVM: nVMX: Support PERF_GLOBAL_CTRL with enlightened VMCS

Enlightened VMCS v1 got updated and now includes the required fields for loading PERF_GLOBAL_CTRL upon VMENTER/VMEXIT features. For KVM on Hyper-V enablement, KVM can just observe VMX control MSRs and use the features (with or without eVMCS) when possible. Hyper-V on KVM is messier as Windows 11 guests fail to boot if the controls are advertised and a new PV feature flag, CPUID.0x4000000A.EBX BIT(0), is not set. Honor the Hyper-V CPUID feature flag to play nice with Windows guests. Signed-off-by: Vitaly Kuznetsov <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
fracktal · Sep 26, 2022 · 4da7709 · 4da7709
1 parent 3ff8a13
commit 4da7709
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Showing 4 changed files with 32 additions and 11 deletions.
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
@@ -2546,7 +2546,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
 		case HYPERV_CPUID_NESTED_FEATURES:
 			ent->eax = evmcs_ver;
 			ent->eax |= HV_X64_NESTED_MSR_BITMAP;
-
+			ent->ebx |= HV_X64_NESTED_EVMCS1_PERF_GLOBAL_CTRL;
 			break;
 
 		case HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS:

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
@@ -412,10 +412,28 @@ static u32 evmcs_get_unsupported_ctls(enum evmcs_ctrl_type ctrl_type)
 	return evmcs_unsupported_ctrls[ctrl_type][evmcs_rev];
 }
 
-void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata)
+static bool evmcs_has_perf_global_ctrl(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+
+	/*
+	 * PERF_GLOBAL_CTRL has a quirk where some Windows guests may fail to
+	 * boot if a PV CPUID feature flag is not also set.  Treat the fields
+	 * as unsupported if the flag is not set in guest CPUID.  This should
+	 * be called only for guest accesses, and all guest accesses should be
+	 * gated on Hyper-V being enabled and initialized.
+	 */
+	if (WARN_ON_ONCE(!hv_vcpu))
+		return false;
+
+	return hv_vcpu->cpuid_cache.nested_ebx & HV_X64_NESTED_EVMCS1_PERF_GLOBAL_CTRL;
+}
+
+void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 {
 	u32 ctl_low = (u32)*pdata;
 	u32 ctl_high = (u32)(*pdata >> 32);
+	u32 unsupported_ctrls;
 
 	/*
 	 * Hyper-V 2016 and 2019 try using these features even when eVMCS
@@ -424,11 +442,17 @@ void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata)
 	switch (msr_index) {
 	case MSR_IA32_VMX_EXIT_CTLS:
 	case MSR_IA32_VMX_TRUE_EXIT_CTLS:
-		ctl_high &= ~evmcs_get_unsupported_ctls(EVMCS_EXIT_CTRLS);
+		unsupported_ctrls = evmcs_get_unsupported_ctls(EVMCS_EXIT_CTRLS);
+		if (!evmcs_has_perf_global_ctrl(vcpu))
+			unsupported_ctrls |= VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
+		ctl_high &= ~unsupported_ctrls;
 		break;
 	case MSR_IA32_VMX_ENTRY_CTLS:
 	case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
-		ctl_high &= ~evmcs_get_unsupported_ctls(EVMCS_ENTRY_CTRLS);
+		unsupported_ctrls = evmcs_get_unsupported_ctls(EVMCS_ENTRY_CTRLS);
+		if (!evmcs_has_perf_global_ctrl(vcpu))
+			unsupported_ctrls |= VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
+		ctl_high &= ~unsupported_ctrls;
 		break;
 	case MSR_IA32_VMX_PROCBASED_CTLS2:
 		ctl_high &= ~evmcs_get_unsupported_ctls(EVMCS_2NDEXEC);

diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
@@ -42,8 +42,6 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
  *	PLE_GAP                         = 0x00004020,
  *	PLE_WINDOW                      = 0x00004022,
  *	VMX_PREEMPTION_TIMER_VALUE      = 0x0000482E,
- *      GUEST_IA32_PERF_GLOBAL_CTRL     = 0x00002808,
- *      HOST_IA32_PERF_GLOBAL_CTRL      = 0x00002c04,
  *
  * Currently unsupported in KVM:
  *	GUEST_IA32_RTIT_CTL		= 0x00002814,
@@ -61,9 +59,8 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
 	 SECONDARY_EXEC_TSC_SCALING |					\
 	 SECONDARY_EXEC_PAUSE_LOOP_EXITING)
 #define EVMCS1_UNSUPPORTED_VMEXIT_CTRL					\
-	(VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL |				\
-	 VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
-#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL)
+	(VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
+#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (0)
 #define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING)
 
 struct evmcs_field {
@@ -243,7 +240,7 @@ bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa);
 uint16_t nested_get_evmcs_version(struct kvm_vcpu *vcpu);
 int nested_enable_evmcs(struct kvm_vcpu *vcpu,
 			uint16_t *vmcs_version);
-void nested_evmcs_filter_control_msr(u32 msr_index, u64 *pdata);
+void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
 int nested_evmcs_check_controls(struct vmcs12 *vmcs12);
 
 #endif /* __KVM_X86_VMX_EVMCS_H */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
@@ -1931,7 +1931,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		 * features out.
 		 */
 		if (!msr_info->host_initiated && guest_cpuid_has_evmcs(vcpu))
-			nested_evmcs_filter_control_msr(msr_info->index,
+			nested_evmcs_filter_control_msr(vcpu, msr_info->index,
 							&msr_info->data);
 		break;
 	case MSR_IA32_RTIT_CTL: