Messages in this thread | | | Date | Fri, 17 Jan 2014 23:28:06 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH] x86, CPU, AMD: Add workaround for family 16h, erratum 793 |
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On Tue 2014-01-14 17:27:23, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > This adds the workaround for erratum 793 as a precaution in case not > every BIOS implements it. This addresses CVE-2013-6885. > > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > arch/x86/kernel/cpu/amd.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c > index 4a48e8bbd857..e4d6f8c91f51 100644 > --- a/arch/x86/kernel/cpu/amd.c > +++ b/arch/x86/kernel/cpu/amd.c > @@ -507,6 +507,17 @@ static void early_init_amd(struct cpuinfo_x86 *c) > set_cpu_cap(c, X86_FEATURE_EXTD_APICID); > } > #endif > + > +#define MSR_AMD_LS_CFG 0xc0011020 > + /* F16h, models 00h-0fh, erratum 793 */ > + if (c->x86 == 0x16 && c->x86_model <= 0xf) { > + u64 val; > + > + rdmsrl(MSR_AMD_LS_CFG, val); > + if (!(val & BIT(15))) > + wrmsrl(MSR_AMD_LS_CFG, val | BIT(15));
Would it make sense to printk() a warning?
BIOS is clearly buggy in this case, and it may cause problems with another operating system, earlier kernel, or maybe early in boot before MSR is written... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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