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

[Jessica Yu]

+++ Peter Zijlstra [03/04/20 18:41 +0200]:
> 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 :/.

Hm, I can look into exposing load_info to arch module code and will
post a patch on Monday.

Jessica