Michael Kelley
5e7d8ddf2a
commit6941f67ad3upstream. Current code in netvsc_drv_init() incorrectly assumes that PAGE_SIZE is 4 Kbytes, which is wrong on ARM64 with 16K or 64K page size. As a result, the default VMBus ring buffer size on ARM64 with 64K page size is 8 Mbytes instead of the expected 512 Kbytes. While this doesn't break anything, a typical VM with 8 vCPUs and 8 netvsc channels wastes 120 Mbytes (8 channels * 2 ring buffers/channel * 7.5 Mbytes/ring buffer). Unfortunately, the module parameter specifying the ring buffer size is in units of 4 Kbyte pages. Ideally, it should be in units that are independent of PAGE_SIZE, but backwards compatibility prevents changing that now. Fix this by having netvsc_drv_init() hardcode 4096 instead of using PAGE_SIZE when calculating the ring buffer size in bytes. Also use the VMBUS_RING_SIZE macro to ensure proper alignment when running with page size larger than 4K. Cc: <stable@vger.kernel.org> # 5.15.x Fixes:7aff79e297("Drivers: hv: Enable Hyper-V code to be built on ARM64") Signed-off-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/20240122162028.348885-1-mhklinux@outlook.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.