From: Dave Hansen <dave.hansen@intel.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
LKML <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2] x86: disable non-instrumented version of copy_mc when KMSAN is enabled
Date: Tue, 5 Mar 2024 07:21:38 -0800 [thread overview]
Message-ID: <74d900cf-ab90-49ea-ba55-380d7df59526@intel.com> (raw)
In-Reply-To: <3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp>
On 3/1/24 14:52, Tetsuo Handa wrote:
> unsigned long __must_check copy_mc_to_kernel(void *dst, const void *src, unsigned len)
> {
> - if (copy_mc_fragile_enabled)
> + if (!IS_ENABLED(CONFIG_KMSAN) && copy_mc_fragile_enabled)
> return copy_mc_fragile(dst, src, len);
> - if (static_cpu_has(X86_FEATURE_ERMS))
> + if (!IS_ENABLED(CONFIG_KMSAN) && static_cpu_has(X86_FEATURE_ERMS))
> return copy_mc_enhanced_fast_string(dst, src, len);
> memcpy(dst, src, len);
> return 0;
> @@ -74,14 +74,14 @@ unsigned long __must_check copy_mc_to_user(void __user *dst, const void *src, un
> {
> unsigned long ret;
>
> - if (copy_mc_fragile_enabled) {
> + if (!IS_ENABLED(CONFIG_KMSAN) && copy_mc_fragile_enabled) {
> __uaccess_begin();
> ret = copy_mc_fragile((__force void *)dst, src, len);
> __uaccess_end();
> return ret;
> }
>
> - if (static_cpu_has(X86_FEATURE_ERMS)) {
> + if (!IS_ENABLED(CONFIG_KMSAN) && static_cpu_has(X86_FEATURE_ERMS)) {
> __uaccess_begin();
> ret = copy_mc_enhanced_fast_string((__force void *)dst, src, len);
> __uaccess_end();
Where does the false positive _come_ from? Can we fix copy_mc_fragile()
and copy_mc_enhanced_fast_string() instead of just not using them?
The three enable_copy_mc_fragile() are presumably doing so for a reason.
What is this patch's impact on _those_?
Third, instead of sprinkling IS_ENABLED(CONFIG_KMSAN) checks in random
spots, can we do this in a central spot?
next prev parent reply other threads:[~2024-03-05 15:21 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-01 22:52 [PATCH v2] x86: disable non-instrumented version of copy_mc when KMSAN is enabled Tetsuo Handa
2024-03-05 11:31 ` Tetsuo Handa
2024-03-05 16:22 ` Thomas Gleixner
2024-03-05 17:57 ` Linus Torvalds
2024-03-06 22:08 ` Tetsuo Handa
2024-03-07 0:09 ` Linus Torvalds
2024-03-19 12:38 ` Alexander Potapenko
2024-03-06 9:16 ` Ingo Molnar
2024-03-06 10:12 ` Tetsuo Handa
2024-03-05 15:21 ` Dave Hansen [this message]
2024-03-05 16:50 ` Thomas Gleixner
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=74d900cf-ab90-49ea-ba55-380d7df59526@intel.com \
--to=dave.hansen@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/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).