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 <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/hyperv.c | 2 +-
arch/x86/kvm/vmx/evmcs.c | 30 +++++++++++++++++++++++++++---
arch/x86/kvm/vmx/evmcs.h | 9 +++------
arch/x86/kvm/vmx/vmx.c | 2 +-
4 files changed, 32 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index a7478b61088b..0adf4a437e85 100644
--- 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
index b64e29f1359f..5fc4834be1f6 100644
--- 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
index f886a8ff0342..d0b2861325a0 100644
--- 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
index d4ed802947d7..f91f09db6e65 100644
--- 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:
--
2.37.2
