From patchwork Thu Mar 11 08:01:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Righi X-Patchwork-Id: 1450984 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4Dx1d5422dz9sWb; Thu, 11 Mar 2021 19:02:17 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1lKGGs-0003Eg-1J; Thu, 11 Mar 2021 08:02:14 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lKGGr-0003EU-6d for kernel-team@lists.ubuntu.com; Thu, 11 Mar 2021 08:02:13 +0000 Received: from mail-ej1-f72.google.com ([209.85.218.72]) by youngberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lKGGq-00050b-UR for kernel-team@lists.ubuntu.com; Thu, 11 Mar 2021 08:02:13 +0000 Received: by mail-ej1-f72.google.com with SMTP id si4so8425866ejb.23 for ; Thu, 11 Mar 2021 00:02:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=RpbM6NDxUykBsju3/0DKYzNNJxANScqAhhtfgZIwgBQ=; b=HQQy0MyK4G9LkjpUevar6G08qyqvkQ6sgNfu8bn2qnH5Eqq71tooN6JCla8iA31L1t qKVqj/rfnOS0O1WXDJWG9DdvPbYH+eAvSOnf/kqGlixZWPXjNs9mHeqD4uSuas3aPMBp ENyjGKTEv2xQJIJ0tMAAMBNaSfZLECzn8XjoKaLAAsVmem4f30TzJO4idM6lBCMz8KgZ /i3jG79vzUzlyqrAKyuxkPl6tOR6B6eHZDL/ctX42h/uoLYWQpwYK+qIMjpdR88m1jJq 9eVKL3+0XMVyPnqWGnS75PSpok3VmMpa1tCxdojxkHm9SKEsCPoCygyhNgOkA/CJ/P3N oW1w== X-Gm-Message-State: AOAM531grBnXyoUB8k5/CRJxDfTxwiRRe+5RGUKQpeO8yP+8Dgd9DpOq 8LvalJzOMsNar215PgZAcipvBnCHgrxy8Hv8FX+LJ60CEyKaFfP4ndCOHlzYGi9WbTZeCbYxIhE sHQGD2cTzb849cyDTPPNgiFKXzC/egov4f75BS5l+Ug== X-Received: by 2002:a17:906:388d:: with SMTP id q13mr1930128ejd.34.1615449732610; Thu, 11 Mar 2021 00:02:12 -0800 (PST) X-Google-Smtp-Source: ABdhPJxNKOuRNhnjAYJCGxvICdLjLjjFpExbvNVQtPfVTnCmVRGxbEzKKGHaAqsowxmz12Et22+3nw== X-Received: by 2002:a17:906:388d:: with SMTP id q13mr1930110ejd.34.1615449732421; Thu, 11 Mar 2021 00:02:12 -0800 (PST) Received: from xps-13-7390.homenet.telecomitalia.it (host-95-235-132-1.retail.telecomitalia.it. [95.235.132.1]) by smtp.gmail.com with ESMTPSA id k26sm865984ejx.81.2021.03.11.00.02.11 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Mar 2021 00:02:11 -0800 (PST) From: Andrea Righi To: kernel-team@lists.ubuntu.com Subject: [SRU][X/aws][PATCH v2 0/1] aws: revert change to support instance types > 255 cpu cores Date: Thu, 11 Mar 2021 09:01:55 +0100 Message-Id: <20210311080155.47562-1-andrea.righi@canonical.com> X-Mailer: git-send-email 2.30.1 MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" BugLink: https://bugs.launchpad.net/bugs/1918590 [Impact] In LP: #1913739 we applied a fix to properly detect the right amount of cores in AWS large instance types (> 255). However, this fix seems to work properly only with kernels > 4.4. Even if it doesn't seem to introduce any failure or regression, it is probably just safer to revert this commit in the Xenial kernel, and keep it on the other kernels (> 4.4). [Test plan] Boot an instance type with > 255 cpus and check the amount of cores detected. [Fix] Revert commit: 561ef22a7d396289a1c5a1d18057ccdf9bb59826 ("iommu/vt-d: Gracefully handle DMAR units with no supported address widths") [Regression potential] Reverting the commit simply restores the old behavior, so we won't be able to detect the right amount of CPUs in large instances, but we are sure that we won't also introduce any potential failure or regressions by restoring the previous behavior. And this is affecting only the Xenial kernel, that is approaching to EOL. ChangeLog (v1 -> v2): - create a new bug instead of re-using the old one when the original fix was applied Acked-by: Guilherme G. Piccoli