[PATCH v2 12/28] KVM: VMX: Enable VM_{EXIT,ENTRY}_LOAD_IA32_PERF_GLOBAL_CTRL for KVM on Hyper-V

[Vitaly Kuznetsov]

The updated Enlightened VMCS v1 specification gained
{guest,host}_ia32_perf_global_ctrl fields so there's no need to filter
VM_{EXIT,ENTRY}_LOAD_IA32_PERF_GLOBAL_CTRL out. Unfortunately, enabling
these controls for Hyper-V on KVM results in boot time crashes and the
exact reason is not clear yet. It is, however, possible to enable the
feature for KVM on Hyper-V as it seems to work.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
 arch/x86/kvm/vmx/evmcs.c | 10 ++++++++--
 arch/x86/kvm/vmx/evmcs.h |  5 ++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index 4fe65b6a9a92..697590cf5b10 100644
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c
@@ -384,11 +384,17 @@ static u32 evmcs_get_unsupported_ctls(struct kvm_vcpu *vcpu,
 	if (!evmcs_rev)
 		return 0;
 
+	/*
+	 * While GUEST_IA32_PERF_GLOBAL_CTRL and HOST_IA32_PERF_GLOBAL_CTRL
+	 * are present in eVMCSv1, Windows 11 still has issues booting when
+	 * VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL/VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL
+	 * are exposed to it, keep them filtered out.
+	 */
 	switch (ctrl_type) {
 	case EVMCS_EXIT_CTLS:
-		return EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
+		return EVMCS1_UNSUPPORTED_VMEXIT_CTRL | VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
 	case EVMCS_ENTRY_CTLS:
-		return EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
+		return EVMCS1_UNSUPPORTED_VMENTRY_CTRL | VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
 	case EVMCS_2NDEXEC:
 		if (evmcs_rev == 1)
 			return EVMCS1_UNSUPPORTED_2NDEXEC | SECONDARY_EXEC_TSC_SCALING;
diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index 2992e29b81b7..c9090ac39740 100644
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h
@@ -68,9 +68,8 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
 	 SECONDARY_EXEC_SHADOW_VMCS |					\
 	 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 {
-- 
2.35.3