linux-kernel - [PATCH v11 22/23] KVM: nVMX: Add consistency checks for CR0.WP and CR4.CET

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Message-ID: <20250704085027.182163-23-chao.gao@intel.com>
Date: Fri,  4 Jul 2025 01:49:53 -0700
From: Chao Gao <chao.gao@...el.com>
To: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	seanjc@...gle.com,
	pbonzini@...hat.com,
	dave.hansen@...el.com
Cc: rick.p.edgecombe@...el.com,
	mlevitsk@...hat.com,
	john.allen@....com,
	weijiang.yang@...el.com,
	minipli@...ecurity.net,
	xin@...or.com,
	Chao Gao <chao.gao@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v11 22/23] KVM: nVMX: Add consistency checks for CR0.WP and CR4.CET

Add consistency checks for CR4.CET and CR0.WP in guest-state or host-state
area in the VMCS12. This ensures that configurations with CR4.CET set and
CR0.WP not set result in VM-entry failure, aligning with architectural
behavior.

Signed-off-by: Chao Gao <chao.gao@...el.com>
---
 arch/x86/kvm/vmx/nested.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3e6f7b4fc374..362e241a2cbb 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3108,6 +3108,9 @@ static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu,
 	    CC(!kvm_vcpu_is_legal_cr3(vcpu, vmcs12->host_cr3)))
 		return -EINVAL;
 
+	if (CC(vmcs12->host_cr4 & X86_CR4_CET && !(vmcs12->host_cr0 & X86_CR0_WP)))
+		return -EINVAL;
+
 	if (CC(is_noncanonical_msr_address(vmcs12->host_ia32_sysenter_esp, vcpu)) ||
 	    CC(is_noncanonical_msr_address(vmcs12->host_ia32_sysenter_eip, vcpu)))
 		return -EINVAL;
@@ -3222,6 +3225,9 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
 	    CC(!nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4)))
 		return -EINVAL;
 
+	if (CC(vmcs12->guest_cr4 & X86_CR4_CET && !(vmcs12->guest_cr0 & X86_CR0_WP)))
+		return -EINVAL;
+
 	if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) &&
 	    (CC(!kvm_dr7_valid(vmcs12->guest_dr7)) ||
 	     CC(!vmx_is_valid_debugctl(vcpu, vmcs12->guest_ia32_debugctl, false))))
-- 
2.47.1