[PATCH 6.12 265/460] KVM: nVMX: Add consistency checks for CR0.WP and CR4.CET

Greg Kroah-Hartman
2026-03-23T14:42:27Z

6.12-stable review patch. If anyone has any objections, please let me know.

------------------

From: Chao Gao <chao.gao@intel.com>

[ Upstream commit 8060b2bd2dd05a19ad7ec248489d374f2bd2b057 ]

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.

Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-33-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stable-dep-of: e2ffe85b6d2b ("KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/vmx/nested.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3022,6 +3022,9 @@ static int nested_vmx_check_host_state(s
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;
@@ -3136,6 +3139,9 @@ static int nested_vmx_check_guest_state(
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))))