Re: [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit

[Boris Ostrovsky]

On 11/25/2014 01:24 PM, Borislav Petkov wrote:
> On Tue, Nov 25, 2014 at 01:12:10PM -0500, Boris Ostrovsky wrote:
> > On 11/19/2014 03:52 PM, Greg Kroah-Hartman wrote:
> > > 3.17-stable review patch.  If anyone has any objections, please let me know.
> >
> > This breaks PV on Xen.
> >
> > -boris
> >
> > > ------------------
> > >
> > > From: Borislav Petkov <bp@xxxxxxx>
> > >
> > > commit 85be07c32496dc264661308e4d9d4e9ccaff8072 upstream.
> > >
> > > We should be accessing it through a pointer, like on the BSP.
> > >
> > > Tested-by: Richard Hendershot <rshendershot@xxxxxxxxx>
> > > Fixes: 65cef1311d5d ("x86, microcode: Add a disable chicken bit")
> > > Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >
> > > ---
> > >   arch/x86/kernel/cpu/microcode/core_early.c |    2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > --- a/arch/x86/kernel/cpu/microcode/core_early.c
> > > +++ b/arch/x86/kernel/cpu/microcode/core_early.c
> > > @@ -124,7 +124,7 @@ void __init load_ucode_bsp(void)
> > >   static bool check_loader_disabled_ap(void)
> > >   {
> > >   #ifdef CONFIG_X86_32
> > > -	return __pa_nodebug(dis_ucode_ldr);
> > > +	return *((bool *)__pa_nodebug(&dis_ucode_ldr));
> And practically the same line in check_loader_disabled_bsp() doesn't?


I don't think this routine is called on PV.


-boris



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/