linux-kernel - Re: [RFC PATCH RESEND] x86/cpu: Avoid endless loop to get the number of cache leaves

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Message-ID: <20181206103736.GA3986@zn.tnic>
Date:   Thu, 6 Dec 2018 11:37:36 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Pu Wen <puwen@...on.cn>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH RESEND] x86/cpu: Avoid endless loop to get the number
 of cache leaves

On Thu, Dec 06, 2018 at 03:26:13PM +0800, Pu Wen wrote:
> To get the number of cache leaves on AMD or Hygon platform, it should
> get the value of cpuid leaf 0x8000001d. But on certain broken platform
> such as a not fullly implemented virtual platform(for example Xen),
> the value of the cpuid leaf will nerver be CTYPE_NULL, so the kernel
> will run into an endless loop.
> 
> To fix this problem, add a new enum type CTYPE_MAX to limit the maximum
> cpuid accessing.
> 
> Signed-off-by: Pu Wen <puwen@...on.cn>
> ---
>  arch/x86/kernel/cpu/cacheinfo.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Did you not see my reply to this last time?

https://lkml.kernel.org/r/20181115172155.GB25056@zn.tnic

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.