Re: [PATCH 1/2] x86/pat: fix x86_has_pat_wp()

[Juergen Gross <jgross@suse.com>]

[-- Attachment #1.1.1: Type: text/plain, Size: 1134 bytes --]

Ping?

On 03.05.22 15:22, Juergen Gross wrote:
> x86_has_pat_wp() is using a wrong test, as it relies on the normal
> PAT configuration used by the kernel. In case the PAT MSR has been
> setup by another entity (e.g. BIOS or Xen hypervisor) it might return
> false even if the PAT configuration is allowing WP mappings.
> 
> Fixes: 1f6f655e01ad ("x86/mm: Add a x86_has_pat_wp() helper")
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>   arch/x86/mm/init.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index d8cfce221275..71e182ebced3 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -80,7 +80,8 @@ static uint8_t __pte2cachemode_tbl[8] = {
>   /* Check that the write-protect PAT entry is set for write-protect */
>   bool x86_has_pat_wp(void)
>   {
> -	return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP;
> +	return __pte2cachemode_tbl[__cachemode2pte_tbl[_PAGE_CACHE_MODE_WP]] ==
> +	       _PAGE_CACHE_MODE_WP;
>   }
>   
>   enum page_cache_mode pgprot2cachemode(pgprot_t pgprot)


[-- Attachment #1.1.2: OpenPGP public key --]
[-- Type: application/pgp-keys, Size: 3149 bytes --]

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 495 bytes --]