From: Dave Hansen <dave.hansen@intel.com>
To: Rik van Riel <riel@surriel.com>, Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>, Xin Li <xin@zytor.com>
Subject: Re: [PATCH] x86/entry: Read CR2 in asm entry stub to redcue NMI clobbering window
Date: Wed, 13 May 2026 09:31:41 -0700 [thread overview]
Message-ID: <ac9af1cf-c123-4959-afed-2a8297b473c9@intel.com> (raw)
In-Reply-To: <20260513121259.0aae7adc@fangorn>
On 5/13/26 09:12, Rik van Riel wrote:
> This reduces the NMI/RC2 race window by 90% -- from hundreds of C
> instructions deep in the handler down to ~30 asm instructions in
> error_entry.
I'm all for using the FRED data. That's a no-brainer.
But I'm not sure the assembly and plumbing is worth it just to _reduce_
but not eliminate a race for non-FRED systems.
What's the actual end-user-visible fallout from the race? Don't we just
see the KASAN fault, skip it, IRET from the #PF and repeat the #PF?
next prev parent reply other threads:[~2026-05-13 16:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 16:12 [PATCH] x86/entry: Read CR2 in asm entry stub to redcue NMI clobbering window Rik van Riel
2026-05-13 16:31 ` Dave Hansen [this message]
2026-05-13 16:43 ` Rik van Riel
2026-05-13 17:12 ` Dave Hansen
2026-05-14 19:49 ` Andrew Cooper
2026-05-14 19:55 ` Dave Hansen
2026-05-14 18:09 ` kernel test robot
2026-05-14 22:54 ` kernel test robot
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=ac9af1cf-c123-4959-afed-2a8297b473c9@intel.com \
--to=dave.hansen@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=kernel-team@meta.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=riel@surriel.com \
--cc=tglx@kernel.org \
--cc=x86@kernel.org \
--cc=xin@zytor.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.