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[109.243.146.38]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b4869c4f93esm1851477866b.83.2025.10.09.00.20.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Oct 2025 00:20:57 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 8083191a-a4e0-11f0-9d15-b5c5bf9af7f9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1759994458; x=1760599258; darn=lists.xenproject.org; h=in-reply-to:from:content-language:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=dRhPB+SBv+gVf3IoqV9gY0z8jXaR6voQ7qNuqH58cJQ=; b=ZElhXaTUBug8gy0PYzZoBvM6umwj3VDB4PAiyd9v7qw3GlUDhYGF5Jl0zkjV4qrOEr CO7/eBNp+gBVW/ji1ite8jQ5B5whwWdIySnYTDeInzqpW/IEGtlpWLpRfHRis42rMNkE WNWJtP3RSlhHfYR+iOCpu0sOSBV+O3ggHGJk1ta4nVog08O7sY3b30jEC+11kO7XcSCJ tGG5MmqOLJO3VSGw8haWPIKGoOmxqcy9LaM6Zkv6zf1Zq5fGHZizUUt/oJ0i2UkTQ391 Lu2Hr/JDJpbrFHx+vpRu562WLmtmU0SNgxrrs3IFVOoPCKtQlODgpFcSNsY+Zp1tGFbu RxFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759994458; x=1760599258; h=in-reply-to:from:content-language:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=dRhPB+SBv+gVf3IoqV9gY0z8jXaR6voQ7qNuqH58cJQ=; b=Gc5OW8kOjTLguMEL3lHeXA9GaldN81Ep+hxIM2byVp6eAPW63i4o9q2d1hQIGAUG8w M3ZzFsaL8hWt4/92ZTaxvxxYpOjj2DqeLttbp6JDDjDxv3wfPqmfLzBbsygYQyFtJEVT s6jA187h9v8px5JNdaSsaU8XTjQqZbPAIHDTHxYyTUaJfG1iwavOVMj89tWs69l1l6PF EeBRwoW0c45140rIHa0bKEtRtmlazhGtGHX1IODwY4HMouACEUhfjsAmstZrzJEVMKUA dDfpeutYayPHxjF3A7Me44hoNHL0QyLm+OiX5w9UyHG26Lcu6pdJr5MFS7DLx2Y6cJzk UhMA== X-Gm-Message-State: AOJu0YytLL4CcQRwCGKxCYBphppBXn2sKpL+oKY2NIQtTqlzDLFbFl1Y 1Ab9PMWm/gmYxWFWzHdminBn7EO++7K47/sK0nohj+j7dJQZ+JW17GJA X-Gm-Gg: ASbGncvwYG7mTZc+8tBzOUnUbVh9x0C10FxwEmiRSJEB8ardKALvw1P19BE31O5ltdF y20UsLb/Sf2CaGkQiNfx9aIW/+NNO2PzU6uqbmhtHLSu1t/7JjirSE8ppLB00jpqqroiSgEg0Nk erJfacc8uM6Bg9vrCWwthhEPPPdDQpHq7NeAdjAdTezW1sD2XJtp6sTvZHHggHDrqJ5e/dzhxLg X7AIZsZjcvDLs5g45HqGV9+XvSGnVHMtPCA0/+bpOPrUb3orY4zbjwgPfKlLJBCseoKcLAACx1X qxk6dMZUc9gQzWyQ3QPKgH/3gMmxbMaVdQJKeJzD2oPM9M7YCAR1CNuEjx5XYCmd+D685H/sZEj cmqONckqFIg0fmAPXUrwqv0ATfbpmy7r06NkgMQCB12fpEjgM8M1f+sLkQZ5IphtTkc9un/CorD sLvw4op038CJ6mDddArLOq+AeEN8G2UR+rqtHdGw== X-Google-Smtp-Source: AGHT+IGkzVao23veRHXKB1kn9GyD/R4JNbCJ3h7Kv1N4zc8e6hdilu0zsLKlIUNU7Fi2SD0uPHRqrg== X-Received: by 2002:a17:907:7e82:b0:b45:66f6:6a21 with SMTP id a640c23a62f3a-b50abfcd081mr706116866b.46.1759994457674; Thu, 09 Oct 2025 00:20:57 -0700 (PDT) Content-Type: multipart/alternative; boundary="------------9O0KnNKyInfmwlzblJbKGynO" Message-ID: Date: Thu, 9 Oct 2025 09:20:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH for-4.21 1/2] x86/AMD: avoid REP MOVSB for Zen3/4 To: Jan Beulich Cc: xen-devel@lists.xenproject.org, Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Jason Andryuk , Teddy Astie References: <8ecbf8b7-91fe-4f9e-9542-7ec22b6a47bb@suse.com> <6bcaa5b7-4e34-40c9-85e6-48a0a5869b86@suse.com> <485889ed-2820-4bb3-b450-88553dbb719e@vates.tech> <7c403caf-192a-413b-9b17-d8e02c066727@suse.com> Content-Language: en-US From: Oleksii Kurochko In-Reply-To: <7c403caf-192a-413b-9b17-d8e02c066727@suse.com> This is a multi-part message in MIME format. --------------9O0KnNKyInfmwlzblJbKGynO Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/8/25 6:06 PM, Jan Beulich wrote: > On 08.10.2025 13:20, Roger Pau Monné wrote: >> On Mon, Sep 29, 2025 at 07:35:53PM -0400, Jason Andryuk wrote: >>> On 2025-09-25 08:18, Teddy Astie wrote: >>>> Le 25/09/2025 à 12:48, Jan Beulich a écrit : >>>>> Along with Zen2 (which doesn't expose ERMS), both families reportedly >>>>> suffer from sub-optimal aliasing detection when deciding whether REP MOVSB >>>>> can actually be carried out the accelerated way. Therefore we want to >>>>> avoid its use in the common case (memset(), copy_page_hot()). >>>> s/memset/memcpy (memset probably uses rep stosb which is not affected IIUC) >>>> >>>>> Reported-by: Andrew Cooper >>>>> Signed-off-by: Jan Beulich >>> With Teddy's suggested change: >>> >>> Reviewed-by: Jason Andryuk >> Acked-by: Roger Pau Monné > May I ask for a release-ack here, seeing that it alters behavior that went in > close before the freeze? Release-Acked-by: Oleksii Kurochko ~ Oleksii --------------9O0KnNKyInfmwlzblJbKGynO Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit


On 10/8/25 6:06 PM, Jan Beulich wrote:
On 08.10.2025 13:20, Roger Pau Monné wrote:

On Mon, Sep 29, 2025 at 07:35:53PM -0400, Jason Andryuk wrote:

On 2025-09-25 08:18, Teddy Astie wrote:

Le 25/09/2025 à 12:48, Jan Beulich a écrit :

Along with Zen2 (which doesn't expose ERMS), both families reportedly
suffer from sub-optimal aliasing detection when deciding whether REP MOVSB
can actually be carried out the accelerated way. Therefore we want to
avoid its use in the common case (memset(), copy_page_hot()).

s/memset/memcpy (memset probably uses rep stosb which is not affected IIUC)


Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>

With Teddy's suggested change:

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

May I ask for a release-ack here, seeing that it alters behavior that went in
close before the freeze?
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

~ Oleksii
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