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.

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>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 11e5d3569933a8dac9a9c4476f528fd0d98fdd4f..51c50ce9e011301740c970b7305b6d780df703a7 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3110,6 +3110,9 @@ 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;
@@ -3224,6 +3227,9 @@ 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))))