From: Dave Hansen <dave.hansen@intel.com>
To: Sohil Mehta <sohil.mehta@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
Kai Huang <kai.huang@intel.com>,
Sandipan Das <sandipan.das@amd.com>,
Breno Leitao <leitao@debian.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Alexei Starovoitov <ast@kernel.org>, Hou Tao <houtao1@huawei.com>,
Juergen Gross <jgross@suse.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Kees Cook <kees@kernel.org>, Eric Biggers <ebiggers@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Yuntao Wang <ytcoode@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Tejun Heo <tj@kernel.org>, Changbin Du <changbin.du@huawei.com>,
Huang Shijie <shijie@os.amperecomputing.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Namhyung Kim <namhyung@kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-efi@vger.kernel.org, linux-mm@kvack.org,
Yian Chen <yian.chen@intel.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Ard Biesheuvel <ardb@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Xiongwei Song <xiongwei.song@windriver.com>,
Xin Li <xin3.li@intel.com>,
"Mike Rapoport (IBM)" <rppt@kernel.org>,
Brijesh Singh <brijesh.singh@amd.com>,
Michael Roth <michael.roth@amd.com>,
Tony Luck <tony.luck@intel.com>,
Alexey Kardashevskiy <aik@amd.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>
Subject: Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits
Date: Fri, 20 Jun 2025 11:24:43 -0700 [thread overview]
Message-ID: <adaf2d81-75b5-4f02-99ea-03ea0f1a5a96@intel.com> (raw)
In-Reply-To: <248e272c-79ec-4c11-a3a8-dff1de2147c0@intel.com>
On 6/20/25 11:14, Sohil Mehta wrote:
> @Dave Hansen, you had suggested separating out the SMAP/LASS AC toggle
> functions. But, the difference in usage between both of them seems very
> subtle. Could this be easily misused?
Logically there are two completely different things:
1. Touching userspace
2. Touching the lower half of the address space
If it's only userspace in the lower half of the address space, then
there's no controversy. But the problem obviously occurs when you want
to touch kernel mappings in the lower half of the address space.
I want to preserve the "stac/clas" meaning as just "touch userspace".
The new functions should be for "touch the lower half of the address
space" alone. Maybe it should be:
lass_disable_enforcement()
lass_enable_enforcement()
The only downside of not having stac/clac in the names is that it's not
obvious that they have an impact on SMAP because they're named to be
LASS-only. But I'm not super worried about this. If we have a
proliferation of call sites we have bigger problem on our hands.
next prev parent reply other threads:[~2025-06-20 18:24 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250620135325.3300848-1-kirill.shutemov@linux.intel.com>
[not found] ` <20250620135325.3300848-9-kirill.shutemov@linux.intel.com>
2025-06-20 14:47 ` [PATCHv6 08/16] x86/traps: Consolidate user fixups in exc_general_protection() Dave Hansen
[not found] ` <20250620135325.3300848-14-kirill.shutemov@linux.intel.com>
2025-06-20 15:20 ` [PATCHv6 13/16] x86/traps: Handle LASS thrown #SS Xin Li
2025-06-20 17:53 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-4-kirill.shutemov@linux.intel.com>
2025-06-20 15:33 ` [PATCHv6 03/16] x86/alternatives: Disable LASS when patching kernel alternatives Dave Hansen
2025-06-20 17:18 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-5-kirill.shutemov@linux.intel.com>
2025-06-20 15:35 ` [PATCHv6 04/16] x86/efi: Move runtime service initialization to arch/x86 Dave Hansen
2025-06-20 17:42 ` Kirill A. Shutemov
2025-06-20 15:38 ` [PATCHv6 00/16] x86: Enable Linear Address Space Separation support Dave Hansen
2025-06-20 22:04 ` Andrew Cooper
2025-06-20 22:29 ` H. Peter Anvin
2025-06-20 22:43 ` H. Peter Anvin
2025-06-20 22:46 ` Dave Hansen
[not found] ` <20250620135325.3300848-6-kirill.shutemov@linux.intel.com>
2025-06-20 15:44 ` [PATCHv6 05/16] x86/cpu: Defer CR pinning setup until after EFI initialization Dave Hansen
[not found] ` <20250620135325.3300848-7-kirill.shutemov@linux.intel.com>
2025-06-20 15:55 ` [PATCHv6 06/16] efi: Disable LASS around set_virtual_address_map() EFI call Dave Hansen
2025-06-20 17:50 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-2-kirill.shutemov@linux.intel.com>
2025-06-20 15:25 ` [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits Dave Hansen
2025-06-20 15:36 ` Xin Li
2025-06-20 17:31 ` Kirill A. Shutemov
2025-06-20 23:46 ` Xin Li
2025-06-21 0:45 ` H. Peter Anvin
2025-06-21 0:50 ` H. Peter Anvin
2025-06-23 17:40 ` Xin Li
2025-06-24 2:04 ` H. Peter Anvin
2025-06-24 4:57 ` Xin Li
2025-06-24 5:11 ` Xin Li
2025-06-20 16:02 ` Randy Dunlap
2025-06-20 16:12 ` Xin Li
2025-06-20 16:16 ` Randy Dunlap
2025-06-20 16:35 ` Borislav Petkov
2025-06-20 17:33 ` Kirill A. Shutemov
2025-06-20 18:29 ` Borislav Petkov
2025-06-23 8:17 ` Kirill A. Shutemov
2025-06-23 10:21 ` Borislav Petkov
2025-06-23 13:42 ` Kirill A. Shutemov
2025-06-26 15:18 ` Borislav Petkov
2025-06-26 16:07 ` Borislav Petkov
2025-06-26 17:21 ` Dave Hansen
2025-06-27 10:25 ` Kirill A. Shutemov
2025-06-27 10:43 ` Borislav Petkov
2025-06-27 13:57 ` Dave Hansen
2025-06-20 18:14 ` Sohil Mehta
2025-06-20 18:24 ` Dave Hansen [this message]
2025-06-20 23:10 ` Sohil Mehta
2025-06-23 16:25 ` Luck, Tony
2025-06-23 16:42 ` Dave Hansen
2025-06-23 23:13 ` Luck, Tony
2025-06-23 23:36 ` H. Peter Anvin
2025-06-24 0:10 ` Luck, Tony
2025-06-24 2:03 ` H. Peter Anvin
2025-06-25 18:51 ` H. Peter Anvin
[not found] ` <20250620135325.3300848-8-kirill.shutemov@linux.intel.com>
2025-06-20 18:43 ` [PATCHv6 07/16] x86/vsyscall: Reorganize the #PF emulation code Dave Hansen
2025-06-20 23:08 ` Andrew Cooper
2025-06-20 23:18 ` Sohil Mehta
2025-06-20 23:29 ` Andrew Cooper
2025-06-20 23:21 ` Dave Hansen
2025-06-21 3:35 ` H. Peter Anvin
2025-06-23 12:41 ` Kirill A. Shutemov
2025-06-23 12:46 ` Andrew Cooper
2025-06-23 15:32 ` Dave Hansen
2025-06-23 15:45 ` Andrew Cooper
2025-06-24 11:37 ` Kirill A. Shutemov
2025-06-24 14:11 ` Dave Hansen
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=adaf2d81-75b5-4f02-99ea-03ea0f1a5a96@intel.com \
--to=dave.hansen@intel.com \
--cc=acme@redhat.com \
--cc=aik@amd.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=ardb@kernel.org \
--cc=ast@kernel.org \
--cc=bp@alien8.de \
--cc=brijesh.singh@amd.com \
--cc=changbin.du@huawei.com \
--cc=christophe.leroy@csgroup.eu \
--cc=corbet@lwn.net \
--cc=daniel.sneddon@linux.intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=ebiggers@google.com \
--cc=geert+renesas@glider.be \
--cc=houtao1@huawei.com \
--cc=hpa@zytor.com \
--cc=jgg@ziepe.ca \
--cc=jgross@suse.com \
--cc=jpoimboe@kernel.org \
--cc=kai.huang@intel.com \
--cc=kees@kernel.org \
--cc=kirill.shutemov@linux.intel.com \
--cc=leitao@debian.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-efi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux@rasmusvillemoes.dk \
--cc=luto@kernel.org \
--cc=mcgrof@kernel.org \
--cc=mhiramat@kernel.org \
--cc=michael.roth@amd.com \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=paulmck@kernel.org \
--cc=pawan.kumar.gupta@linux.intel.com \
--cc=peterz@infradead.org \
--cc=rick.p.edgecombe@intel.com \
--cc=rppt@kernel.org \
--cc=sandipan.das@amd.com \
--cc=shijie@os.amperecomputing.com \
--cc=sohil.mehta@intel.com \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=tony.luck@intel.com \
--cc=vegard.nossum@oracle.com \
--cc=x86@kernel.org \
--cc=xin3.li@intel.com \
--cc=xiongwei.song@windriver.com \
--cc=yian.chen@intel.com \
--cc=ytcoode@gmail.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;
as well as URLs for NNTP newsgroup(s).