On Tue, Jun 15, 2021, Sean Christopherson wrote: > 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. Ugh, I misread .Ldefault_entry in head_32.S, it skips over the entire EFER code if PAE=0. Apparently I didn't test this with non-PAE paging and EPT? Paolo, I'll send a revert since it's in kvm/next, but even better would be if you can drop the patch :-) Lucky for me you didn't pick up patch 4/4 that depends on this... I'll revisit this mess in a few weeks. > 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 >
