Re: [PATCH v2] x86, AMD: Make cpu_has_amd_erratum() use the correctstruct cpuinfo_x86

From: Borislav Petkov
Date: Wed Aug 07 2013 - 02:51:43 EST

On Tue, Jul 23, 2013 at 07:40:49PM +0200, Torsten Kaiser wrote:
> cpu_has_amd_erratum() is buggy, because it uses the per-cpu cpu_info
> before it is filled by smp_store_boot_cpu_info() / smp_store_cpu_info().
> If early microcode loading is enabled its collect_cpu_info_amd_early() will
> fill ->x86 and so the fallback to boot_cpu_data is not used.
> But ->x86_vendor was not filled and is still 0 == X86_VENDOR_INTEL resulting in
> no errata fixes getting applied and my system hangs on boot.
> Using cpu_info in cpu_has_amd_erratum() is wrong anyway: Its only caller
> init_amd() will have a struct cpuinfo_x86 as parameter and the set_cpu_bug()
> that is controlled by cpu_has_amd_erratum() also only uses that struct.
> So pass the struct cpuinfo_x86 from init_amd() to cpu_has_amd_erratum() and
> the broken fallback can be dropped.
> I also added an WARN_ON() into the vendor check because init_amd() can only
> be used by AMD CPUs and if the current failure hadn't been silent this bug
> would have been much more obvious.
> V2: At request of Borislav Petkov: BUG_ON -> WARN_ON and subject change
> Signed-off-by: Torsten Kaiser <just.for.lkml@xxxxxxxxxxxxxx>

Acked-by: Borislav Petkov <bp@xxxxxxx>


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