From: Dave Hansen <dave.hansen@intel.com>
To: Sairaj Kodilkar <sarunkod@amd.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Thomas Gleixner <tglx@kernel.org>,
Uros Bizjak <ubizjak@gmail.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org
Cc: vasant.hegde@amd.com, suravee.suthikulpanit@amd.com
Subject: Re: [PATCH v3 1/2] x86/uaccess: Extend CMPXCHG user helpers to 128-bit operands
Date: Wed, 26 Aug 2026 05:30:55 -0700 [thread overview]
Message-ID: <e32c1437-44ab-45d9-9534-124a9e09f029@intel.com> (raw)
In-Reply-To: <20260826070004.8100-2-sarunkod@amd.com>
On 8/26/26 00:00, Sairaj Kodilkar wrote:
> Extend the existing user CMPXCHG helpers to support 16-byte operands on
> x86-64, using LOCK_PREFIX "cmpxchg16b". This mirrors the existing
> __try_cmpxchg64_user_asm() / cmpxchg8b path provided for 32-bit kernels,
> where KVM needs an atomic compare-exchange wider than the generic
> cmpxchg helper can provide.
Please take a good look at the Sashiko review:
https://sashiko.dev/#/patchset/20260826070004.8100-2-sarunkod%40amd.com
It looks like the "A" constraint isn't one that you can cleanly mirror
from cmpxchg8b => cmpxchg16b.
Uros, any chance you can give these a good once-over? This seems to be
just the kind of thing you've been fixing up lately. It would be nice to
get them right the first time.
next prev parent reply other threads:[~2026-08-26 12:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-26 7:00 [PATCH v3 0/2] Add support for cmpxchg16b emulation Sairaj Kodilkar
2026-08-26 7:00 ` [PATCH v3 1/2] x86/uaccess: Extend CMPXCHG user helpers to 128-bit operands Sairaj Kodilkar
2026-08-26 7:23 ` sashiko-bot
2026-08-26 8:54 ` Sairaj Kodilkar
2026-08-26 12:30 ` Dave Hansen [this message]
2026-08-26 13:19 ` Uros Bizjak
2026-08-26 13:28 ` Sairaj Kodilkar
2026-08-27 9:01 ` David Laight
2026-08-26 7:00 ` [PATCH v3 2/2] KVM: x86: Add support for cmpxchg16b emulation Sairaj Kodilkar
2026-08-26 7:31 ` sashiko-bot
2026-08-26 9:17 ` Sairaj Kodilkar
2026-08-26 12:50 ` Mathieu Desnoyers
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=e32c1437-44ab-45d9-9534-124a9e09f029@intel.com \
--to=dave.hansen@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=sarunkod@amd.com \
--cc=seanjc@google.com \
--cc=suravee.suthikulpanit@amd.com \
--cc=tglx@kernel.org \
--cc=ubizjak@gmail.com \
--cc=vasant.hegde@amd.com \
--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