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From: Julien Grall <julien.grall@arm.com>
To: xen-devel@lists.xen.org
Cc: andre.przywara@arm.com, Julien Grall <julien.grall@arm.com>,
	sstabellini@kernel.org, wei.chen@arm.com, steve.capper@arm.com
Subject: [PATCH v3 12/16] xen/arm: Document the errata implemented in Xen
Date: Tue,  7 Jun 2016 17:06:19 +0100	[thread overview]
Message-ID: <1465315583-1278-13-git-send-email-julien.grall@arm.com> (raw)
In-Reply-To: <1465315583-1278-1-git-send-email-julien.grall@arm.com>

The new document will help to keep track of each erratum Xen is able to

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 <julien.grall@arm.com>

    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
+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                     |

Xen-devel mailing list

  parent reply	other threads:[~2016-06-07 16:06 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07 16:06 [PATCH v3 00/16] xen/arm: Introduce alternative runtime patching for ARM64 Julien Grall
2016-06-07 16:06 ` [PATCH v3 01/16] xen/arm: Makefile: Sort the entries alphabetically Julien Grall
2016-06-07 16:06 ` [PATCH v3 02/16] xen/arm: Include the header asm-arm/system.h in asm-arm/page.h Julien Grall
2016-06-07 16:06 ` [PATCH v3 03/16] xen/arm: Add macros to handle the MIDR Julien Grall
2016-06-07 16:06 ` [PATCH v3 04/16] xen/arm: Add cpu_hwcap bitmap Julien Grall
2016-06-07 16:06 ` [PATCH v3 05/16] xen/arm64: Add an helper to invalidate all instruction caches Julien Grall
2016-06-07 16:06 ` [PATCH v3 06/16] xen/arm: arm64: Move the define BRK_BUG_FRAME into a separate header Julien Grall
2016-06-07 16:06 ` [PATCH v3 07/16] xen/arm: arm64: Reserve a brk immediate to fault on purpose Julien Grall
2016-06-07 16:06 ` [PATCH v3 08/16] xen/arm: arm64: Add helpers to decode and encode branch instructions Julien Grall
2016-06-07 16:06 ` [PATCH v3 09/16] xen/arm: Introduce alternative runtime patching Julien Grall
2016-06-07 17:24   ` Konrad Rzeszutek Wilk
2016-06-08  9:39     ` Julien Grall
2016-06-08 18:17       ` Konrad Rzeszutek Wilk
2016-06-08 18:22         ` Julien Grall
2016-06-08 18:35           ` Konrad Rzeszutek Wilk
2016-06-09 13:33   ` Julien Grall
2016-06-07 16:06 ` [PATCH v3 10/16] xen/arm: cpufeature: Provide an helper to check if a capability is supported Julien Grall
2016-06-22  9:59   ` Stefano Stabellini
2016-06-22 10:09     ` Julien Grall
2016-06-22 10:14       ` Stefano Stabellini
2016-06-07 16:06 ` [PATCH v3 11/16] xen/arm: Detect silicon revision and set cap bits accordingly Julien Grall
2016-06-22 10:00   ` Stefano Stabellini
2016-06-07 16:06 ` Julien Grall [this message]
2016-06-22 10:03   ` [PATCH v3 12/16] xen/arm: Document the errata implemented in Xen Stefano Stabellini
2016-06-07 16:06 ` [PATCH v3 13/16] xen/arm: arm64: Add Cortex-A53 cache errata workaround Julien Grall
2016-06-22 10:04   ` Stefano Stabellini
2016-06-07 16:06 ` [PATCH v3 14/16] xen/arm: arm64: Add cortex-A57 erratum 832075 workaround Julien Grall
2016-06-22 10:10   ` Stefano Stabellini
2016-06-07 16:06 ` [PATCH v3 15/16] xen/arm: traps: Don't inject a fault if the translation VA -> IPA fails Julien Grall
2016-06-07 16:06 ` [PATCH v3 16/16] xen/arm: arm64: Document Cortex-A57 erratum 834220 Julien Grall
2016-06-14 12:15   ` Julien Grall
2016-06-22 10:08   ` Stefano Stabellini
2016-06-22 10:18     ` Julien Grall
2016-06-22 10:37       ` Stefano Stabellini

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