linux-kernel - Re: [PATCH v5 1/7] mce: fix set_mce_nospec to always unmap the whole page

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Date:   Wed, 2 Feb 2022 05:21:30 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Jane Chu <jane.chu@...cle.com>
Cc:     david@...morbit.com, djwong@...nel.org, dan.j.williams@...el.com,
        hch@...radead.org, vishal.l.verma@...el.com, dave.jiang@...el.com,
        agk@...hat.com, snitzer@...hat.com, dm-devel@...hat.com,
        ira.weiny@...el.com, willy@...radead.org, vgoyal@...hat.com,
        linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org
Subject: Re: [PATCH v5 1/7] mce: fix set_mce_nospec to always unmap the whole
 page

> +static inline int set_mce_nospec(unsigned long pfn)
>  {
>  	unsigned long decoy_addr;
>  	int rc;
> @@ -117,10 +113,7 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
>  	 */
>  	decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
>  
> -	if (unmap)
> -		rc = set_memory_np(decoy_addr, 1);
> -	else
> -		rc = set_memory_uc(decoy_addr, 1);
> +	rc = set_memory_np(decoy_addr, 1);
>  	if (rc)
>  		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
>  	return rc;
> @@ -130,7 +123,7 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
>  /* Restore full speculative operation to the pfn. */
>  static inline int clear_mce_nospec(unsigned long pfn)
>  {
> -	return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
> +	return _set_memory_present((unsigned long) pfn_to_kaddr(pfn), 1);
>  }

Wouldn't it make more sense to move these helpers out of line rather
than exporting _set_memory_present?

>  /*
> - * _set_memory_prot is an internal helper for callers that have been passed
> + * __set_memory_prot is an internal helper for callers that have been passed

This looks unrelated to the patch.