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Re: [PATCH CPU v1] cpuid: initialize cpuinfo with boot_cpu_data
- To: Norbert Manthey <nmanthey@xxxxxxxxx>
- From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Date: Fri, 11 Feb 2022 10:02:34 +0100
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- Cc: <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
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- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Fri, Feb 11, 2022 at 08:23:27AM +0100, Norbert Manthey wrote:
> When re-identifying CPU data, we might use uninitialized data when
> checking for the cache line property to adapt the cache
> alignment. The data that depends on this uninitialized read is
> currently not forwarded.
>
> To avoid problems in the future, initialize the data cpuinfo
> structure before re-identifying the CPU again.
>
> The trace to hit the uninitialized read reported by Coverity is:
>
> bool recheck_cpu_features(unsigned int cpu)
> ...
> struct cpuinfo_x86 c;
> ...
> identify_cpu(&c);
>
> void identify_cpu(struct cpuinfo_x86 *c)
> ...
> generic_identify(c)
>
> static void generic_identify(struct cpuinfo_x86 *c)
> ...
Would it be more appropriate for generic_identify to also set
x86_cache_alignment like it's done in early_cpu_init?
generic_identify already re-fetches a bunch of stuff that's also
set by early_cpu_init for the BSP.
Thanks, Roger.
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