From: Dave Hansen <dave.hansen@linux.intel.com>
To: Yisheng Xie <xieyisheng1@huawei.com>, linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, richard.fellner@student.tugraz.at,
moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at,
michael.schwarz@iaik.tugraz.at, luto@kernel.org,
torvalds@linux-foundation.org, keescook@google.com,
hughd@google.com, x86@kernel.org
Subject: Re: [PATCH 05/23] x86, kaiser: unmap kernel from userspace page tables (core patch)
Date: Thu, 4 Jan 2018 21:18:02 -0800 [thread overview]
Message-ID: <93776eb2-b6d4-679a-280c-8ba558a69c34@linux.intel.com> (raw)
In-Reply-To: <e80ac5b1-c562-fc60-ee84-30a3a40bde60@huawei.com>
On 01/04/2018 08:16 PM, Yisheng Xie wrote:
>> === Page Table Poisoning ===
>>
>> KAISER has two copies of the page tables: one for the kernel and
>> one for when running in userspace.
>
> So, we have 2 page table, thinking about this case:
> If _ONE_ process includes _TWO_ threads, one run in user space, the other
> run in kernel, they can run in one core with Hyper-Threading, right?
Yes.
> So both userspace and kernel space is valid, right? And for one core
> with Hyper-Threading, they may share TLB, so the timing problem
> described in the paper may still exist?
No. The TLB is managed per logical CPU (hyperthread), as is the CR3
register that points to the page tables. Two threads running the same
process might use the same CR3 _value_, but that does not mean they
share TLB entries.
One thread *can* be in the kernel with the kernel page tables while the
other is in userspace with the user page tables active. They will even
use a different PCID/ASID for the same page tables normally.
> Can this case still be protected by KAISER?
Yes.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2018-01-05 5:18 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-23 0:34 [PATCH 00/23] [v4] KAISER: unmap most of the kernel from userspace page tables Dave Hansen
2017-11-23 0:34 ` [PATCH 01/23] x86, kaiser: disable global pages by default with KAISER Dave Hansen
2017-11-23 0:34 ` [PATCH 02/23] x86, kaiser: prepare assembly for entry/exit CR3 switching Dave Hansen
2017-11-23 0:34 ` [PATCH 03/23] x86, kaiser: introduce user-mapped per-cpu areas Dave Hansen
2017-11-23 0:34 ` [PATCH 04/23] x86, kaiser: mark per-cpu data structures required for entry/exit Dave Hansen
2017-11-23 0:34 ` [PATCH 05/23] x86, kaiser: unmap kernel from userspace page tables (core patch) Dave Hansen
2017-11-23 4:07 ` Andy Lutomirski
2017-11-26 16:10 ` Andy Lutomirski
2017-11-26 16:24 ` Dave Hansen
2017-11-26 16:29 ` Andy Lutomirski
2018-01-05 4:16 ` Yisheng Xie
2018-01-05 5:18 ` Dave Hansen [this message]
2018-01-05 6:16 ` Yisheng Xie
2018-01-05 6:29 ` Dave Hansen
2018-01-05 11:49 ` Andrea Arcangeli
2018-01-05 18:19 ` Jiri Kosina
2018-01-05 19:00 ` Jiri Kosina
2018-01-05 19:03 ` Dave Hansen
2018-01-05 19:17 ` Jiri Kosina
2018-01-05 19:18 ` Jiri Kosina
2018-01-05 19:55 ` Andrea Arcangeli
2018-01-05 21:07 ` Dave Hansen
2018-01-05 21:14 ` Jiri Kosina
2018-01-05 21:29 ` Andy Lutomirski
2018-01-05 22:48 ` Hugh Dickins
2018-01-06 4:54 ` Hanjun Guo
2018-01-06 6:06 ` Dave Hansen
2018-01-06 6:28 ` Hanjun Guo
2018-01-06 6:53 ` Hanjun Guo
2018-01-06 7:55 ` Dave Hansen
2018-01-06 8:42 ` Hanjun Guo
2018-01-06 7:51 ` Dave Hansen
2018-01-06 17:22 ` Andrea Arcangeli
2017-11-23 0:34 ` [PATCH 06/23] x86, kaiser: allow NX poison to be set in p4d/pgd Dave Hansen
2017-11-23 0:34 ` [PATCH 07/23] x86, kaiser: make sure static PGDs are 8k in size Dave Hansen
2017-11-23 0:34 ` [PATCH 08/23] x86, kaiser: map cpu entry area Dave Hansen
2017-11-23 0:34 ` [PATCH 09/23] x86, kaiser: map dynamically-allocated LDTs Dave Hansen
2017-11-23 19:42 ` Eric Biggers
2017-11-23 20:12 ` Andy Lutomirski
2017-11-23 0:34 ` [PATCH 10/23] x86, kaiser: map espfix structures Dave Hansen
2017-11-23 0:34 ` [PATCH 11/23] x86, kaiser: map entry stack variables Dave Hansen
2017-11-23 3:31 ` Andy Lutomirski
2017-11-23 15:37 ` Dave Hansen
2017-11-23 15:55 ` Andy Lutomirski
2017-11-23 0:35 ` [PATCH 12/23] x86, kaiser: map virtually-addressed performance monitoring buffers Dave Hansen
2017-11-23 0:35 ` [PATCH 13/23] x86, mm: Move CR3 construction functions Dave Hansen
2017-11-23 0:35 ` [PATCH 14/23] x86, mm: remove hard-coded ASID limit checks Dave Hansen
2017-11-23 0:35 ` [PATCH 15/23] x86, mm: put mmu-to-h/w ASID translation in one place Dave Hansen
2017-11-23 0:35 ` [PATCH 16/23] x86, pcid, kaiser: allow flushing for future ASID switches Dave Hansen
2017-11-23 0:35 ` [PATCH 17/23] x86, kaiser: use PCID feature to make user and kernel switches faster Dave Hansen
2017-11-23 0:35 ` [PATCH 18/23] x86, kaiser: disable native VSYSCALL Dave Hansen
2017-11-23 0:35 ` [PATCH 19/23] x86, kaiser: add debugfs file to turn KAISER on/off at runtime Dave Hansen
2017-11-23 0:35 ` [PATCH 20/23] x86, kaiser: add a function to check for KAISER being enabled Dave Hansen
2017-11-25 1:23 ` Eduardo Valentin
2017-11-23 0:35 ` [PATCH 21/23] x86, kaiser: un-poison PGDs at runtime Dave Hansen
2017-11-25 1:17 ` Eduardo Valentin
2017-11-23 0:35 ` [PATCH 22/23] x86, kaiser: allow KAISER to be enabled/disabled " Dave Hansen
2017-11-23 0:35 ` [PATCH 23/23] x86, kaiser: add Kconfig Dave Hansen
2017-11-23 7:23 ` [PATCH 00/23] [v4] KAISER: unmap most of the kernel from userspace page tables Ingo Molnar
2017-11-23 7:27 ` Ingo Molnar
2017-11-23 7:32 ` Ingo Molnar
2017-11-23 15:02 ` Dave Hansen
2017-11-23 16:20 ` Dave Hansen
2017-11-24 6:35 ` Ingo Molnar
2017-11-24 6:41 ` Dave Hansen
2017-11-24 7:33 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=93776eb2-b6d4-679a-280c-8ba558a69c34@linux.intel.com \
--to=dave.hansen@linux.intel.com \
--cc=daniel.gruss@iaik.tugraz.at \
--cc=hughd@google.com \
--cc=keescook@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=michael.schwarz@iaik.tugraz.at \
--cc=moritz.lipp@iaik.tugraz.at \
--cc=richard.fellner@student.tugraz.at \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
--cc=xieyisheng1@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox