From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] x86/speculation/l1tf: suggest what to do on systems with too much RAM
Date: Fri, 24 Aug 2018 12:36:34 +0200 [thread overview]
Message-ID: <d789bd84-a982-b8bb-ee24-6a7fcdf8221d@suse.cz> (raw)
In-Reply-To: <966571f0-9d7f-43dc-92c6-a10eec7a1254@suse.cz>
On 08/24/2018 09:32 AM, Vlastimil Babka wrote:
> On 08/23/2018 09:27 PM, Michal Hocko wrote:
>> On Thu 23-08-18 16:28:12, Vlastimil Babka wrote:
>>> Two users have reported [1] that they have an "extremely unlikely" system
>>> with more than MAX_PA/2 memory and L1TF mitigation is not effective. Let's
>>> make the warning more helpful by suggesting the proper mem=X kernel boot param,
>>> a rough calculation of how much RAM can be lost (not precise if there's holes
>>> between MAX_PA/2 and max_pfn in the e820 map) and a link to the L1TF document
>>> to help decide if the mitigation is worth the unusable RAM.
>>>
>>> [1] https://bugzilla.suse.com/show_bug.cgi?id=1105536
>>>
>>> Suggested-by: Michal Hocko <mhocko@suse.com>
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>>
>> I wouldn't bother with max_pfn-half_pa part but other than that this is
>> much more useful than the original message.
>
> Right, and it causes build failures on some configs.
>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>
> Thanks! Here's a v2:
Just realized that kvm printk's refer to the online version at
https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html
which should be easier for the users of distro kernels, should I change
that?
next prev parent reply other threads:[~2018-08-24 10:36 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 13:44 [PATCH] x86/speculation/l1tf: fix off-by-one error when warning that system has too much RAM Vlastimil Babka
2018-08-23 13:56 ` Michal Hocko
2018-08-23 14:28 ` [PATCH] x86/speculation/l1tf: suggest what to do on systems with " Vlastimil Babka
2018-08-23 15:46 ` Andi Kleen
2018-08-23 19:25 ` Michal Hocko
2018-08-23 19:38 ` Andi Kleen
2018-08-23 20:05 ` Michal Hocko
2018-08-23 22:07 ` Andi Kleen
2018-08-23 19:03 ` kbuild test robot
2018-08-23 19:23 ` kbuild test robot
2018-08-23 19:27 ` Michal Hocko
2018-08-24 7:32 ` Vlastimil Babka
2018-08-24 7:55 ` [tip:x86/urgent] x86/speculation/l1tf: Suggest " tip-bot for Vlastimil Babka
2018-08-24 10:36 ` Vlastimil Babka [this message]
2018-08-24 12:10 ` [PATCH] x86/speculation/l1tf: suggest " Vlastimil Babka
2018-08-24 12:20 ` Michal Hocko
2018-08-24 13:57 ` [tip:x86/urgent] x86/speculation/l1tf: Suggest " tip-bot for Vlastimil Babka
2018-08-23 15:44 ` [PATCH] x86/speculation/l1tf: fix off-by-one error when warning that system has " Andi Kleen
2018-08-23 20:20 ` Vlastimil Babka
2018-08-24 2:22 ` Andre Tomt
2018-08-24 3:35 ` Andi Kleen
2018-08-29 2:04 ` Christopher Snowhill
2018-08-24 8:52 ` xxxxxx xxxxxx
2018-08-24 7:55 ` [tip:x86/urgent] x86/speculation/l1tf: Fix " tip-bot for Vlastimil Babka
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