linux-kernel - Re: [PATCH 2/4] x86/mm/cpa: Fix cpa_flush

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Message-ID: <bb2d868c-b986-5000-8b27-26b852235ab1@intel.com>
Date:   Fri, 30 Nov 2018 09:43:16 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>, luto@...nel.org
Cc:     x86@...nel.org, Tom.StDenis@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] x86/mm/cpa: Fix cpa_flush_array()

> +void __cpa_flush_array(void *data)
>  {
> -	unsigned int i, level;
> +	struct cpa_data *cpa = data;
> +	unsigned int i;
>  
> -	if (__cpa_flush_range(baddr, numpages, cache))
> +	for (i = 0; i < cpa->numpages; i++)
> +		__flush_tlb_one_kernel(__cpa_addr(cpa, i));
> +}

While I guess it won't _hurt_ anything, we do have cases where
__cpa_addr() can return 0.  So, won't this be flushing virtual address
0x0 unnecessarily for those?