2e9ca760c2
This reverts commit 762faee5a2678559d3dc09d95f8f2c54cd0466a7.
This has been reported to trip up guests on GCP (Google Cloud).
The reason is that virtio_find_vqs_ctx_size is broken on legacy
devices. We can in theory fix virtio_find_vqs_ctx_size but
in fact the patch itself has several other issues:
- It treats unknown speed as < 10G
- It leaves userspace no way to find out the ring size set by hypervisor
- It tests speed when link is down
- It ignores the virtio spec advice:
Both \field{speed} and \field{duplex} can change, thus the driver
is expected to re-read these values after receiving a
configuration change notification.
- It is not clear the performance impact has been tested properly
Revert the patch for now.
Reported-by: Andres Freund <andres@anarazel.de>
Link: https://lore.kernel.org/r/20220814212610.GA3690074%40roeck-us.net
Link: https://lore.kernel.org/r/20220815070203.plwjx7b3cyugpdt7%40awork3.anarazel.de
Link: https://lore.kernel.org/r/3df6bb82-1951-455d-a768-e9e1513eb667%40www.fastmail.com
Link: https://lore.kernel.org/r/FCDC5DDE-3CDD-4B8A-916F-CA7D87B547CE%40anarazel.de
Fixes: 762faee5a267 ("virtio_net: set the default max ring size by find_vqs()")
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Andres Freund <andres@anarazel.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Message-Id: <20220816053602.173815-2-mst@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.