Re: [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect

[Peter Zijlstra]

On Fri, Apr 03, 2020 at 09:36:05AM -0700, Sean Christopherson wrote:
> On Thu, Apr 02, 2020 at 02:32:59PM +0200, Thomas Gleixner wrote:
> > --- a/arch/x86/kernel/module.c
> > +++ b/arch/x86/kernel/module.c
> > @@ -24,6 +24,7 @@
> >  #include <asm/pgtable.h>
> >  #include <asm/setup.h>
> >  #include <asm/unwind.h>
> > +#include <asm/cpu.h>
> >  
> >  #if 0
> >  #define DEBUGP(fmt, ...)				\
> > @@ -253,6 +254,11 @@ int module_finalize(const Elf_Ehdr *hdr,
> >  					    tseg, tseg + text->sh_size);
> >  	}
> >  
> > +	if (text && !me->sld_safe) {
> 
> As also reported by the test bot, sld_safe only exist if CPU_SUP_INTEL=y.
> 
> This can also be conditioned on boot_cpu_has(X86_FEATURE_VMX), or the
> static variant.  If CPU_SUP_INTEL=y, X86_FEATURE_VMX will be set if and
> only if VMX is fully enabled, i.e. supported by the CPU and enabled in
> MSR_IA32_FEATURE_CONTROl.
> 
> > +		void *tseg = (void *)text->sh_addr;
> > +		split_lock_validate_module_text(me, tseg, tseg + text->sh_size);
> > +	}

Ideally we push it all into arch code, but load_info isn't exposed to
arch module code :/.