From: Sean Christopherson Date: Tue, 15 Jun 2021 16:45:34 +0000 (-0700) Subject: KVM: x86: WARN and reject loading KVM if NX is supported but not enabled X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8bbed95d2cb6e5de8a342d761a89b0a04faed7be;p=linux.git KVM: x86: WARN and reject loading KVM if NX is supported but not enabled 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 Reviewed-by: Jim Mattson Message-Id: <20210615164535.2146172-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8b898ec8d349b..76dae88cf5248 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10920,6 +10920,9 @@ 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);