mirror of
https://github.com/xen-project/xen.git
synced 2026-10-28 02:01:24 +01:00
Jan Beulich
93401e28a8
Inspired by Linux commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24:
There have been reports of RDRAND issues after resuming from suspend on
some AMD family 15h and family 16h systems. This issue stems from a BIOS
not performing the proper steps during resume to ensure RDRAND continues
to function properly.
Update the CPU initialization to clear the RDRAND CPUID bit for any family
15h and 16h processor that supports RDRAND. If it is known that the family
15h or family 16h system does not have an RDRAND resume issue or that the
system will not be placed in suspend, the "cpuid=rdrand" kernel parameter
can be used to stop the clearing of the RDRAND CPUID bit.
Note, that clearing the RDRAND CPUID bit does not prevent a processor
that normally supports the RDRAND instruction from executing it. So any
code that determined the support based on family and model won't #UD.
Warn if no explicit choice was given on affected hardware.
Check RDRAND functions at boot as well as after S3 resume (the retry
limit chosen is entirely arbitrary).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Sphinx documentation:
All source rendered by Sphinx is licensed under CC-BY-4.0.
You are free to:
Share:
Copy and redistribute the material in any medium or format.
Adapt:
Remix, transform, and build upon the material for any purpose, even
commercially.
Under the following terms:
Attribution:
You must give appropriate credit, provide a link to the license, and
indicate if changes were made. You may do so in any reasonable manner, but
not in any way that suggests the licensor endorses you or your use.
No additional restrictions:
You may not apply legal terms or technological measures that legally
restrict others from doing anything the license permits.
See https://creativecommons.org/licenses/by/4.0/ for full details.
This includes:
* All ReStructured Text files: docs/*/*.rst
* The Sphinx configuration file: docs/conf.py
* Content in Sphinx-exclusive subdirs: docs/*-guide/*
Other documentation:
There are a variety of text documents in various formats. These, given no
explicit license guidance, fall under Xen's default GPL-2.0 license.