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[192.237.175.120]) by mx.google.com with ESMTPS id u60si5165625uau.44.2016.05.05.09.36.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 May 2016 09:36:04 -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 1ayMEl-0001zo-Q1; Thu, 05 May 2016 16:34:51 +0000 Received: from mail6.bemta6.messagelabs.com ([85.158.143.247]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ayMEk-0001lL-Gw for xen-devel@lists.xen.org; Thu, 05 May 2016 16:34:50 +0000 Received: from [85.158.143.35] by server-2.bemta-6.messagelabs.com id E6/6B-09532-A267B275; Thu, 05 May 2016 16:34:50 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrGLMWRWlGSWpSXmKPExsVysyfVTVezTDv cYOI+PYslHxezODB6HN39mymAMYo1My8pvyKBNePp/DlsBb/FKy7f/MDSwDhTuIuRi0NIYCOj xPwvm1ggnNOMEjO7VzJ2MXJysAloStz5/IkJxBYRkJa49vkyI0gRs0Azo8T0Ra/ZQBLCAi4Sr T/PsXYxcnCwCKhKHDquCxLmFXCVeLqskwXElhCQkzh5bDIriM0JFF96fiVYXAio9eSOSWwTGL kXMDKsYlQvTi0qSy3SNdRLKspMzyjJTczM0TU0MNPLTS0uTkxPzUlMKtZLzs/dxAj0LwMQ7GD c+dzpEKMkB5OSKO92Je1wIb6k/JTKjMTijPii0pzU4kOMMhwcShK8cqVAOcGi1PTUirTMHGCg waQlOHiURHglQNK8xQWJucWZ6RCpU4yKUuK8CiAJAZBERmkeXBssuC8xykoJ8zICHSLEU5Bal JtZgir/ilGcg1FJmJcJZApPZl4J3PRXQIuZgBa/n6sJsrgkESEl1cDIpdFZPoWL437bss6sah FPuW+/vh3v62zdcO+ofUOU+7E/x11utk8PkzO6HpJ0VqJtqoxHs+fd81GlRu6vSplvXlpzkuf 0Lq3T/ycLula0u7OpKHqulGDZzWp/uvkHu5Dco94tXNXVUq8t13K5XJ/pnb5WfE5ULp/vuyKF Zo3r4uuDgixCE5VYijMSDbWYi4oTAefYiR1pAgAA X-Env-Sender: julien.grall@arm.com X-Msg-Ref: server-15.tower-21.messagelabs.com!1462466089!12769270!1 X-Originating-IP: [217.140.101.70] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 8.34; banners=-,-,- X-VirusChecked: Checked Received: (qmail 51449 invoked from network); 5 May 2016 16:34:49 -0000 Received: from foss.arm.com (HELO foss.arm.com) (217.140.101.70) by server-15.tower-21.messagelabs.com with SMTP; 5 May 2016 16:34:49 -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 6D2693A; Thu, 5 May 2016 09:34:55 -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 083DA3F252; Thu, 5 May 2016 09:34:46 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xen.org Date: Thu, 5 May 2016 17:34:21 +0100 Message-Id: <1462466065-30212-13-git-send-email-julien.grall@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1462466065-30212-1-git-send-email-julien.grall@arm.com> References: <1462466065-30212-1-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] [RFC 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 all the erratum that 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 --- 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..3f0d32b --- /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 Linux). + +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. 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 |