WARN if NX is reported as supported but not enabled in EFER. All flavors of the kernel, including non-PAE 32-bit kernels, set EFER.NX=1 if NX is supported, even if NX usage is disable via kernel command line. KVM relies on NX being enabled if it's supported, e.g. KVM will generate illegal NPT entries if nx_huge_pages is enabled and NX is supported but not enabled. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index acc28473dec7..1f6595df45de 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10981,6 +10981,9 @@ int kvm_arch_hardware_setup(void *opaque) int r; rdmsrl_safe(MSR_EFER, &host_efer); + if (WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_NX) && + !(host_efer & EFER_NX))) + return -EIO; if (boot_cpu_has(X86_FEATURE_XSAVES)) rdmsrl(MSR_IA32_XSS, host_xss); -- 2.32.0.272.g935e593368-goog
