From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A8B0331EC4 for ; Tue, 30 Jun 2026 13:27:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782826030; cv=none; b=h3wtalXPXmo+WChwYlO1UXLu9Lf+/HlnkEkxozX/DOet7il1wAodJTHGQSCA7N6yk/X7vuLbqXvNro/X2ZSDEQ2baMwYHd2gIIIGmT6sDGhs5V0aHWY+0WBb9JLCjvullGtBOtEkSA7CCXyNdtkAeCw//Bi8qtm3Sj+PL0SCuhw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782826030; c=relaxed/simple; bh=JR0hGwTifJi23hQUsyAsADVEClBXYGGkf9VvR/h2S04=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=nXzm9mdq4Y8Vgvf2nPnRp1xYwQPczwzJwKiBiwiGe7l6vV51G8SxL86ACpCq0UdPX51WU0xA7Tdq3RHhTY1NqKhftT7Rm5xehwMMBKoNnHJJBb66ZxSkfIdf4hk7jNDNA/VViX4zJGKeKqvPkEo2mv2n1WKPGPm+qCnTrhuna/Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aMXfYWgi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aMXfYWgi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 141751F01559; Tue, 30 Jun 2026 13:27:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782826029; bh=DU/Bw85yAGRkAgKfd7D4X6rowR2P8Ik/CFIUjc+ErJU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=aMXfYWgippeT+COL4lV6VHLJOEXSbyoSwbYU+9535qaA1cWD6ijJwGS0qxvzDE4WX QBtxzmh+UmcqoDp4tGUyykhCDA3lhgZLG6cp68IFKBXbHYtAlBl8IIuEeY037mh1+T aRqiw9dUdF7ozjUGBgneXQE3Oq/NST62khW7JGeVZk7WA8sv2gx7v9I1SlynMEV0FJ miuXjlX6ySJCFGIMEaK9veeqXlKJqBZFY9vnm8g5GLL/RR/vT8hpn0oibfS3Z8Hctj urnTo6r3KRFtsWkUTu1acdenuXF9PGPdZTlAwAA4XVZZ+pvQF2svCxtwTm459a5llJ Be0Ns4wz4rEOQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 2/2] perf/arm-cmn: Add workarounds for CMN-S3 on Graviton5 Reply-To: sashiko-reviews@lists.linux.dev To: "Robin Murphy" Cc: linux-perf-users@vger.kernel.org In-Reply-To: References: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 30 Jun 2026 13:27:08 +0000 Message-Id: <20260630132709.141751F01559@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] The Graviton5 workaround sets the DTC node's logical ID to the X= P's mesh logical ID instead of the DTC domain ID, which can cross-wire PMU = event routing. -- commit d22a8571a1d86b4f3c00bde161d5fb2ce99fe43f Author: Aviv Bakal perf/arm-cmn: Add workarounds for CMN-S3 on Graviton5 This patch adds workarounds for the CMN-S3 implementation on Graviton5, which reports zeroed fields in discovery registers. It introduces an ACPI HID for identification, derives the DTC domain from the XP node ID, and sets the DTC logical ID from the XP's logical ID. > diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c > --- a/drivers/perf/arm-cmn.c > +++ b/drivers/perf/arm-cmn.c [ ... ] > @@ -2475,6 +2500,10 @@ static int arm_cmn_discover(struct arm_cmn *cmn, u= nsigned int rgn_offset) > =20 > switch (dn->type) { > case CMN_TYPE_DTC: > + if (graviton5_workaround) { > + /* Node info logical ID is zeroed; use the XP's */ > + dn->logid =3D xp->logid; [Severity: Medium] Does this code assign the host XP's mesh logical ID to the DTC node instead of the computed domain ID (xp->dtc)? If the DTC nodes' mesh logical IDs do not sort into the exact same order as their domain IDs, will the array indices be cross-wired, potentially misrouting PMU events? Event configuration looks up the cmn->dtc[] array using the node's domain ID (dn->dtc). Could this instead be dn->logid =3D xp->dtc; to restore the correct semantic meaning of a DTC's logical ID as its domain index? > + } > cmn->num_dtcs++; > dn++; > break; --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/cover.1782824005.gi= t.robin.murphy@arm.com?part=3D2