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[192.237.175.120]) by mx.google.com with ESMTPS id m125si6876177vkg.20.2016.06.07.09.08.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Jun 2016 09:08:19 -0700 (PDT) Received-SPF: neutral (google.com: 192.237.175.120 is neither permitted nor denied by best guess record for domain of xen-devel-bounces@lists.xen.org) client-ip=192.237.175.120; Authentication-Results: mx.google.com; spf=neutral (google.com: 192.237.175.120 is neither permitted nor denied by best guess record for domain of xen-devel-bounces@lists.xen.org) smtp.mailfrom=xen-devel-bounces@lists.xen.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bAJWk-0002TI-Ce; Tue, 07 Jun 2016 16:06:50 +0000 Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bAJWj-0002MH-Hj for xen-devel@lists.xen.org; Tue, 07 Jun 2016 16:06:49 +0000 Received: from [193.109.254.147] by server-10.bemta-14.messagelabs.com id EA/3B-31433-911F6575; Tue, 07 Jun 2016 16:06:49 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrGLMWRWlGSWpSXmKPExsVysyfVTVfiY1i 4QUuTtsWSj4tZHBg9ju7+zRTAGMWamZeUX5HAmtEzaRdzwTHJitUH57I0MK4U6WLk4hAS2MAo 8WPqbjYI5zSjxJVfR5i7GDk52AQ0Je58/sQEYosISEtc+3yZEcRmFmhmlFh4wA/EFhbwlHi7+ C0LiM0ioCqxr2sLO4jNK+Aise7xA7C4hICcxMljk1lBbE6geNuDR2wgtpCAs8TSXw2MExi5Fz AyrGJUL04tKkst0jXXSyrKTM8oyU3MzNE1NDTRy00tLk5MT81JTCrWS87P3cQI9C8DEOxg/LL E+RCjJAeTkijv52dh4UJ8SfkplRmJxRnxRaU5qcWHGGU4OJQkeAvfAeUEi1LTUyvSMnOAgQaT luDgURLhzQJJ8xYXJOYWZ6ZDpE4xKkqJ8+qAJARAEhmleXBtsOC+xCgrJczLCHSIEE9BalFuZ gmq/CtGcQ5GJWFeM5ApPJl5JXDTXwEtZgJavOxaMMjikkSElFQDo08yj+RjpaWvt91zr9y48d SE4+YH7h/8X+xjmn1baMqnQofDjnY83z/n52dLHpMPLHjjZsXLFbp/v+mLgh0FDyQPqz+7V6n Xenn24+j5JmVuRc/+hGTK2l9iFuA5nWyh9OW44+s3AfeWOx/6f4L/Sd1un/oVHV2vr9vuVfE/ 7rLGMUG+WMHfQImlOCPRUIu5qDgRAI1sxBRpAgAA X-Env-Sender: julien.grall@arm.com X-Msg-Ref: server-12.tower-27.messagelabs.com!1465315608!46311673!1 X-Originating-IP: [217.140.101.70] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 8.46; banners=-,-,- X-VirusChecked: Checked Received: (qmail 7368 invoked from network); 7 Jun 2016 16:06:48 -0000 Received: from foss.arm.com (HELO foss.arm.com) (217.140.101.70) by server-12.tower-27.messagelabs.com with SMTP; 7 Jun 2016 16:06:48 -0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 46F5AF; Tue, 7 Jun 2016 09:07:22 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.215.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B5AFC3F21A; Tue, 7 Jun 2016 09:06:46 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xen.org Date: Tue, 7 Jun 2016 17:06:19 +0100 Message-Id: <1465315583-1278-13-git-send-email-julien.grall@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1465315583-1278-1-git-send-email-julien.grall@arm.com> References: <1465315583-1278-1-git-send-email-julien.grall@arm.com> Cc: andre.przywara@arm.com, Julien Grall , sstabellini@kernel.org, wei.chen@arm.com, steve.capper@arm.com Subject: [Xen-devel] [PATCH v3 12/16] xen/arm: Document the errata implemented in Xen X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" The new document will help to keep track of each erratum Xen is able to handle. The text is based on the Linux doc in Documents/arm64/silicon-errata.txt. Also list the current errata that Xen is aware of. Signed-off-by: Julien Grall --- Changes in v3: - Fix grammar in the commit message - s/Linux/Xen/ - Mention that runtime patching is only supported by ARM64 --- docs/misc/arm/silicon-errata.txt | 45 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 docs/misc/arm/silicon-errata.txt diff --git a/docs/misc/arm/silicon-errata.txt b/docs/misc/arm/silicon-errata.txt new file mode 100644 index 0000000..374a63a --- /dev/null +++ b/docs/misc/arm/silicon-errata.txt @@ -0,0 +1,45 @@ + Silicon Errata and Software Workarounds + ======================================= + +It is an unfortunate fact of life that hardware is often produced with +so-called "errata", which can cause it to deviate from the architecture +under specific circumstances. For hardware produced by ARM, these +errata are broadly classified into the following categories: + + Category A: A critical error without a viable workaround. + Category B: A significant or critical error with an acceptable + workaround. + Category C: A minor error that is not expected to occur under normal + operation. + +For more information, consult one of the "Software Developers Errata +Notice" documents available on infocenter.arm.com (registration +required). + +As far as Xen is concerned, Category B errata may require some special +treatment in the hypervisor. For example, avoiding a particular sequence +of code, or configuring the processor in a particular way. A less common +situation may require similar actions in order to declassify a Category A +erratum into a Category C erratum. These are collectively known as +"software workarounds" and are only required in the minority of cases +(e.g. those cases that both require a non-secure workaround *and* can +be triggered by Xen). + +For software workarounds that may adversely impact systems unaffected by +the erratum in question, a Kconfig entry is added under "ARM errata +workarounds via the alternatives framework". These are enabled by default +and patched in at runtime when an affected CPU is detected. Note that +runtime patching is only supported by ARM64. For less-intrusive workarounds, +a Kconfig option is not available and the code is structured (preferably +with a comment) in such a way that the erratum will not be hit. + +This approach can make it slightly onerous to determine exactly which +errata are worked around in an arbitrary hypervisor source tree, so this +file acts as a registry of software workarounds in the Xen hypervisor and +will be updated when new workarounds are committed and backported to +stable hypervisors. + +| Implementor | Component | Erratum ID | Kconfig | ++----------------+-----------------+-----------------+-------------------------+ +| ARM | Cortex-A15 | #766422 | N/A | +| ARM | Cortex-A57 | #852523 | N/A |