linux-kernel - Re: [PATCH v6 1/4] cacheinfo: Check for null last-level cache info

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Message-ID: <20240911233746.GB7043@ranerica-svr.sc.intel.com>
Date: Wed, 11 Sep 2024 16:37:46 -0700
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org, Andreas Herrmann <aherrmann@...e.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Chen Yu <yu.c.chen@...el.com>, Len Brown <len.brown@...el.com>,
	Radu Rendec <rrendec@...hat.com>,
	Pierre Gondois <Pierre.Gondois@....com>, Pu Wen <puwen@...on.cn>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Sudeep Holla <sudeep.holla@....com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Will Deacon <will@...nel.org>, Zhang Rui <rui.zhang@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	Huang Ying <ying.huang@...el.com>,
	Ricardo Neri <ricardo.neri@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/4] cacheinfo: Check for null last-level cache info

On Wed, Sep 11, 2024 at 04:05:09PM +0200, Borislav Petkov wrote:
> On Wed, Sep 04, 2024 at 11:00:33PM -0700, Ricardo Neri wrote:
> > Before determining the validity of the last-level cache info, ensure that
> > it has been allocated. Simply checking for non-zero cache_leaves() is not
> > sufficient, as some architectures (e.g., Intel processors) have non-zero
> > cache_leaves() before allocation.
> >
> > Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size().
> > This function iterates over all online CPUs. However, a CPU may have come
> > online recently, but its cacheinfo may not have been allocated yet.
> > 
> > Reviewed-by: Andreas Herrmann <aherrmann@...e.de>
> > Reviewed-by: Sudeep Holla <sudeep.holla@....com>
> > Tested-by: Andreas Herrmann <aherrmann@...e.de>
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
> 
> While at it, pls fix the formatting insanity of allocate_cache_info() into:
> 
> static inline int allocate_cache_info(int cpu)
> {
>         per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), sizeof(struct cacheinfo), GFP_ATOMIC);
>         if (!per_cpu_cacheinfo(cpu)) {
>                 cache_leaves(cpu) = 0;
>                 return -ENOMEM;
>         }
>             
>         return 0;
> }
> 
> Thx.

Sure! I can do this. I assume this should be a separate patch.