From: Jane Chu <jane.chu@oracle.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "david@fromorbit.com" <david@fromorbit.com>,
"djwong@kernel.org" <djwong@kernel.org>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"hch@infradead.org" <hch@infradead.org>,
"vishal.l.verma@intel.com" <vishal.l.verma@intel.com>,
"dave.jiang@intel.com" <dave.jiang@intel.com>,
"agk@redhat.com" <agk@redhat.com>,
"snitzer@redhat.com" <snitzer@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
"ira.weiny@intel.com" <ira.weiny@intel.com>,
"willy@infradead.org" <willy@infradead.org>,
"vgoyal@redhat.com" <vgoyal@redhat.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"nvdimm@lists.linux.dev" <nvdimm@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"dave.hansen@intel.com" <dave.hansen@intel.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"luto@kernel.org" <luto@kernel.org>
Subject: Re: [PATCH v7 3/6] mce: fix set_mce_nospec to always unmap the whole page
Date: Wed, 13 Apr 2022 23:41:18 +0000 [thread overview]
Message-ID: <7ef7960a-d505-db5b-06da-96f60c24113a@oracle.com> (raw)
In-Reply-To: <YlVPcrK4SSXyPx+Y@zn.tnic>
On 4/12/2022 3:07 AM, Borislav Petkov wrote:
> On Tue, Apr 05, 2022 at 01:47:44PM -0600, Jane Chu wrote:
>> The set_memory_uc() approach doesn't work well in all cases.
>> For example, when "The VMM unmapped the bad page from guest
>> physical space and passed the machine check to the guest."
>> "The guest gets virtual #MC on an access to that page.
>> When the guest tries to do set_memory_uc() and instructs
>> cpa_flush() to do clean caches that results in taking another
>> fault / exception perhaps because the VMM unmapped the page
>> from the guest."
>
> I presume this is quoting someone...
Yes, will mention Dan's name next time.
>
>> Since the driver has special knowledge to handle NP or UC,
>> let's mark the poisoned page with NP and let driver handle it
>
> s/let's mark/mark/
>
Okay.
>> when it comes down to repair.
>>
>> Please refer to discussions here for more details.
>> https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@mail.gmail.com/
>>
>> Now since poisoned page is marked as not-present, in order to
>> avoid writing to a 'np' page and trigger kernel Oops, also fix
>
> You can write it out: "non-present page..."
Okay.
>
>> pmem_do_write().
>>
>> Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()")
>> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>> ---
>> arch/x86/kernel/cpu/mce/core.c | 6 +++---
>> arch/x86/mm/pat/set_memory.c | 18 ++++++------------
>> drivers/nvdimm/pmem.c | 31 +++++++------------------------
>> include/linux/set_memory.h | 4 ++--
>> 4 files changed, 18 insertions(+), 41 deletions(-)
>
> For such mixed subsystem patches we probably should talk about who picks
> them up, eventually...
Hmm, maintainers' action item?
>
>> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>> index 981496e6bc0e..fa67bb9d1afe 100644
>> --- a/arch/x86/kernel/cpu/mce/core.c
>> +++ b/arch/x86/kernel/cpu/mce/core.c
>> @@ -579,7 +579,7 @@ static int uc_decode_notifier(struct notifier_block *nb, unsigned long val,
>>
>> pfn = mce->addr >> PAGE_SHIFT;
>> if (!memory_failure(pfn, 0)) {
>> - set_mce_nospec(pfn, whole_page(mce));
>> + set_mce_nospec(pfn);
>> mce->kflags |= MCE_HANDLED_UC;
>> }
>>
>> @@ -1316,7 +1316,7 @@ static void kill_me_maybe(struct callback_head *cb)
>>
>> ret = memory_failure(p->mce_addr >> PAGE_SHIFT, flags);
>> if (!ret) {
>> - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page);
>> + set_mce_nospec(p->mce_addr >> PAGE_SHIFT);
>> sync_core();
>> return;
>> }
>> @@ -1342,7 +1342,7 @@ static void kill_me_never(struct callback_head *cb)
>> p->mce_count = 0;
>> pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr);
>> if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0))
>> - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page);
>> + set_mce_nospec(p->mce_addr >> PAGE_SHIFT);
>> }
>
> Both that ->mce_whole_page and whole_page() look unused after this.
>
Yes, indeed, Dan also noticed, will remove while_page() in a follow-on
patch.
thanks,
-jane
next prev parent reply other threads:[~2022-04-13 23:41 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-05 19:47 [PATCH v7 0/6] DAX poison recovery Jane Chu
2022-04-05 19:47 ` [PATCH v7 1/6] x86/mm: fix comment Jane Chu
2022-04-11 22:07 ` Dan Williams
2022-04-12 9:53 ` Borislav Petkov
2022-04-14 1:00 ` Jane Chu
2022-04-14 8:44 ` Borislav Petkov
2022-04-14 21:54 ` Jane Chu
2022-04-05 19:47 ` [PATCH v7 2/6] x86/mce: relocate set{clear}_mce_nospec() functions Jane Chu
2022-04-06 5:01 ` Christoph Hellwig
2022-04-11 22:20 ` Dan Williams
2022-04-14 0:56 ` Jane Chu
2022-04-05 19:47 ` [PATCH v7 3/6] mce: fix set_mce_nospec to always unmap the whole page Jane Chu
2022-04-06 5:02 ` Christoph Hellwig
2022-04-11 23:27 ` Dan Williams
2022-04-13 23:36 ` Jane Chu
2022-04-14 2:32 ` Dan Williams
2022-04-15 16:18 ` Jane Chu
2022-04-12 10:07 ` Borislav Petkov
2022-04-13 23:41 ` Jane Chu [this message]
2022-04-05 19:47 ` [PATCH v7 4/6] dax: add DAX_RECOVERY flag and .recovery_write dev_pgmap_ops Jane Chu
2022-04-06 5:19 ` Christoph Hellwig
2022-04-06 17:32 ` Jane Chu
2022-04-06 17:45 ` Jane Chu
2022-04-07 5:30 ` Christoph Hellwig
2022-04-11 23:55 ` Dan Williams
2022-04-14 0:48 ` Jane Chu
2022-04-14 0:47 ` Jane Chu
2022-04-12 0:08 ` Dan Williams
2022-04-14 0:50 ` Jane Chu
2022-04-12 4:57 ` Dan Williams
2022-04-12 5:02 ` Christoph Hellwig
2022-04-14 0:51 ` Jane Chu
2022-04-05 19:47 ` [PATCH v7 5/6] pmem: refactor pmem_clear_poison() Jane Chu
2022-04-06 5:04 ` Christoph Hellwig
2022-04-06 17:34 ` Jane Chu
2022-04-12 4:26 ` Dan Williams
2022-04-14 0:55 ` Jane Chu
2022-04-14 2:02 ` Dan Williams
2022-04-05 19:47 ` [PATCH v7 6/6] pmem: implement pmem_recovery_write() Jane Chu
2022-04-06 5:21 ` Christoph Hellwig
2022-04-06 17:33 ` Jane Chu
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