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>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>
Subject: Re: [RFT PATCH] x86/pat: Fix set_mce_nospec() for pmem
Date: Tue, 30 Nov 2021 23:00:53 +0000 [thread overview]
Message-ID: <1d34f45c-2b6a-1f4d-71ff-715885f8f41a@oracle.com> (raw)
In-Reply-To: <CAPcyv4g4mEVDcUw2Ph0oMH1=ZQgCbnLx+ZdgoavyOQt+9q6aVw@mail.gmail.com>
On 11/24/2021 4:16 PM, Dan Williams wrote:
> On Thu, Nov 18, 2021 at 11:04 AM Jane Chu <jane.chu@oracle.com> wrote:
>>
>> On 11/13/2021 12:47 PM, Dan Williams wrote:
>> <snip>
<snip>
>>
>> Thanks Dan for taking the time elaborating so much details!
>>
>> After some amount of digging, I have a feel that we need to take
>> dax error handling in phases.
>>
>> Phase-1: the simplest dax_recovery_write on page granularity, along
>> with fix to set poisoned page to 'NP', serialize
>> dax_recovery_write threads.
>
> You mean special case PAGE_SIZE overwrites when dax_direct_access()
> fails, but leave out the sub-page error handling and
> read-around-poison support?
Yes.
>
> That makes sense to me. Incremental is good.
Thanks!
>
>> Phase-2: provide dax_recovery_read support and hence shrink the error
>> recovery granularity. As ioremap returns __iomem pointer
>> that is only allowed to be referenced with helpers like
>> readl() which do not have a mc_safe variant, and I'm
>> not sure whether there should be. Also the synchronization
>> between dax_recovery_read and dax_recovery_write threads.
>
> You can just use memremap() like the driver does to drop the iomem annotation.
Okay, will investigate in phase 2.
>
>> Phase-3: the hypervisor error-record keeping issue, suppose there is
>> an issue, I'll need to figure out how to setup a test case.
>> Phase-4: the how-to-mitigate-MOVDIR64B-false-alarm issue.
>
> My expectation is that CXL supports MOVDIR64B error clearing without
> needing to send the Clear Poison command. I think this can be phase3,
> phase4 is the more difficult question about how / if to coordinate
> with VMM poison tracking. Right now I don't see a choice but to make
> it paravirtualized.
>
>>
>> Right now, it seems to me providing Phase-1 solution is urgent, to give
>> something that customers can rely on.
>>
>> How does this sound to you?
>
> Sounds good.
>
Thanks!
-jane
next prev parent reply other threads:[~2021-11-30 23:01 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
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 [this message]
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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