2de154f541
Provide "error" semantics (read zeros, drop writes) for userspace accesses to MSRs that are ultimately unsupported for whatever reason, but for which KVM told userspace to save and restore the MSR, i.e. for MSRs that KVM included in KVM_GET_MSR_INDEX_LIST. Previously, KVM special cased a few PMU MSRs that were problematic at one point or another. Extend the treatment to all PMU MSRs, e.g. to avoid spurious unsupported accesses. Note, the logic can also be used for non-PMU MSRs, but as of today only PMU MSRs can end up being unsupported after KVM told userspace to save and restore them. Link: https://lore.kernel.org/r/20230124234905.3774678-7-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.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.