mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-01-17 07:13:58 -05:00
ea9ca904d2
KVM does not yet support userspace modifying PMCR_EL0.N (With
the previous patch, KVM ignores what is written by userspace).
Add support userspace limiting PMCR_EL0.N.
Disallow userspace to set PMCR_EL0.N to a value that is greater
than the host value as KVM doesn't support more event counters
than what the host HW implements. Also, make this register
immutable after the VM has started running. To maintain the
existing expectations, instead of returning an error, KVM
returns a success for these two cases.
Finally, ignore writes to read-only bits that are cleared on
vCPU reset, and RES{0,1} bits (including writable bits that
KVM doesn't support yet), as those bits shouldn't be modified
(at least with the current KVM).
Co-developed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Link: https://lore.kernel.org/r/20231020214053.2144305-8-rananta@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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.