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From: Jane Chu <jane.chu@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Borislav Petkov <bp@alien8.de>,
	"Luck, Tony" <tony.luck@intel.com>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	Luis Chamberlain <mcgrof@suse.com>
Subject: Re: [RFT PATCH] x86/pat: Fix set_mce_nospec() for pmem
Date: Fri, 12 Nov 2021 17:57:51 +0000	[thread overview]
Message-ID: <f80d03c6-e650-49df-81d1-309dd138de8f@oracle.com> (raw)
In-Reply-To: <CAPcyv4imjWNuwsQKhWinq+vtuSgXAznhLXVfsy69Dq7q7eiXbA@mail.gmail.com>

On 11/11/2021 4:51 PM, Dan Williams wrote:
> On Thu, Nov 11, 2021 at 4:30 PM Jane Chu <jane.chu@oracle.com> wrote:
>>
>> Just a quick update -
>>
>> I managed to test the 'NP' and 'UC' effect on a pmem dax file.
>> The result is, as expected, both setting 'NP' and 'UC' works
>> well in preventing the prefetcher from accessing the poisoned
>> pmem page.
>>
>> I injected back-to-back poisons to the 3rd block(512B) of
>> the 3rd page in my dax file.  With 'NP', the 'mc_safe read'
>> stops  after reading the 1st and 2nd pages, with 'UC',
>> the 'mc_safe read' was able to read [2 pages + 2 blocks] on
>> my test machine.
> 
> My expectation is that dax_direct_access() / dax_recovery_read() has
> installed a temporary UC alias for the pfn, or has temporarily flipped
> NP to UC. Outside of dax_recovery_read() the page will always be NP.
> 

Okay.  Could we only flip the memtype within dax_recovery_read, and
not within dax_direct_access?  dax_direct_access does not need to
access the page.

thanks,
-jane

  reply	other threads:[~2021-11-12 20:20 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07  1:01 [RFT PATCH] x86/pat: Fix set_mce_nospec() for pmem Dan Williams
2021-08-26 19:08 ` Dan Williams
2021-08-27  7:12   ` Jane Chu
2021-09-13 10:29 ` Borislav Petkov
2021-09-14 18:08   ` Dan Williams
2021-09-15 10:41     ` Borislav Petkov
2021-09-16 20:33       ` Dan Williams
2021-09-17 11:30         ` Borislav Petkov
2021-09-21  2:04           ` Dan Williams
2021-09-30 17:19             ` Borislav Petkov
2021-09-30 17:28               ` Luck, Tony
2021-09-30 19:30                 ` Borislav Petkov
2021-09-30 19:41                   ` Dan Williams
2021-09-30 19:44                   ` Luck, Tony
2021-09-30 20:01                     ` Borislav Petkov
2021-09-30 20:15                       ` Luck, Tony
2021-09-30 20:32                         ` Borislav Petkov
2021-09-30 20:39                           ` Dan Williams
2021-09-30 20:54                             ` Borislav Petkov
2021-09-30 21:05                               ` Dan Williams
2021-09-30 21:20                                 ` Borislav Petkov
2021-09-30 21:41                                   ` Dan Williams
2021-09-30 22:35                                     ` Borislav Petkov
2021-09-30 22:44                                       ` Dan Williams
2021-10-01 10:41                                         ` Borislav Petkov
2021-10-01  0:43                                       ` Jane Chu
2021-10-01  2:02                                         ` Dan Williams
2021-10-01 10:50                                           ` Borislav Petkov
2021-10-01 16:52                                             ` Dan Williams
2021-10-01 18:11                                               ` Borislav Petkov
2021-10-01 18:29                                                 ` Dan Williams
2021-10-02 10:17                                                   ` Borislav Petkov
2021-11-11  0:06                                                     ` Jane Chu
2021-11-12  0:30                                                       ` Jane Chu
2021-11-12  0:51                                                         ` Dan Williams
2021-11-12 17:57                                                           ` Jane Chu [this message]
2021-11-12 19:24                                                             ` Dan Williams
2021-11-12 22:35                                                               ` Jane Chu
2021-11-12 22:50                                                                 ` Jane Chu
2021-11-12 23:08                                                                 ` Dan Williams
2021-11-13  5:50                                                                   ` Jane Chu
2021-11-13 20:47                                                                     ` Dan Williams
2021-11-18 19:03                                                                       ` Jane Chu
2021-11-25  0:16                                                                         ` Dan Williams
2021-11-30 23:00                                                                           ` Jane Chu
2021-09-30 18:15         ` Jane Chu
2021-09-30 19:11           ` Dan Williams
2021-09-30 21:23             ` Jane Chu

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