linux-kernel - [RFC PATCH 17/18] KVM: VMX: Allow MBEC with EVMCS

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Message-ID: <20250313203702.575156-18-jon@nutanix.com>
Date: Thu, 13 Mar 2025 13:36:56 -0700
From: Jon Kohler <jon@...anix.com>
To: seanjc@...gle.com, pbonzini@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: Jon Kohler <jon@...anix.com>
Subject: [RFC PATCH 17/18] KVM: VMX: Allow MBEC with EVMCS

Extend EVMCS1_SUPPORTED_2NDEXEC to understand MBEC enablement,
otherwise presenting both EVMCS and MBEC at the same time will disable
MBEC presentation into the guest.

Signed-off-by: Jon Kohler <jon@...anix.com>

---
 arch/x86/kvm/vmx/hyperv.c       | 5 ++++-
 arch/x86/kvm/vmx/hyperv_evmcs.h | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/hyperv.c b/arch/x86/kvm/vmx/hyperv.c
index fab6a1ad98dc..941a29c9e667 100644
--- a/arch/x86/kvm/vmx/hyperv.c
+++ b/arch/x86/kvm/vmx/hyperv.c
@@ -138,7 +138,10 @@ void nested_evmcs_filter_control_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *
 		ctl_high &= evmcs_get_supported_ctls(EVMCS_EXEC_CTRL);
 		break;
 	case MSR_IA32_VMX_PROCBASED_CTLS2:
-		ctl_high &= evmcs_get_supported_ctls(EVMCS_2NDEXEC);
+		supported_ctrls = evmcs_get_supported_ctls(EVMCS_2NDEXEC);
+		if (!vcpu->arch.pt_guest_exec_control)
+			supported_ctrls &= ~SECONDARY_EXEC_MODE_BASED_EPT_EXEC;
+		ctl_high &= supported_ctrls;
 		break;
 	case MSR_IA32_VMX_TRUE_PINBASED_CTLS:
 	case MSR_IA32_VMX_PINBASED_CTLS:
diff --git a/arch/x86/kvm/vmx/hyperv_evmcs.h b/arch/x86/kvm/vmx/hyperv_evmcs.h
index a543fccfc574..930429f376f9 100644
--- a/arch/x86/kvm/vmx/hyperv_evmcs.h
+++ b/arch/x86/kvm/vmx/hyperv_evmcs.h
@@ -87,6 +87,7 @@
 	 SECONDARY_EXEC_PT_CONCEAL_VMX |				\
 	 SECONDARY_EXEC_BUS_LOCK_DETECTION |				\
 	 SECONDARY_EXEC_NOTIFY_VM_EXITING |				\
+	 SECONDARY_EXEC_MODE_BASED_EPT_EXEC |				\
 	 SECONDARY_EXEC_ENCLS_EXITING)
 
 #define EVMCS1_SUPPORTED_3RDEXEC (0ULL)
-- 
2.43.0