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e9025cdd8c
KVM x86 PMU changes for 6.9: - Fix several bugs where KVM speciously prevents the guest from utilizing fixed counters and architectural event encodings based on whether or not guest CPUID reports support for the _architectural_ encoding. - Fix a variety of bugs in KVM's emulation of RDPMC, e.g. for "fast" reads, priority of VMX interception vs #GP, PMC types in architectural PMUs, etc. - Add a selftest to verify KVM correctly emulates RDMPC, counter availability, and a variety of other PMC-related behaviors that depend on guest CPUID, i.e. are difficult to validate via KVM-Unit-Tests. - Zero out PMU metadata on AMD if the virtual PMU is disabled to avoid wasting cycles, e.g. when checking if a PMC event needs to be synthesized when skipping an instruction. - Optimize triggering of emulated events, e.g. for "count instructions" events when skipping an instruction, which yields a ~10% performance improvement in VM-Exit microbenchmarks when a vPMU is exposed to the guest. - Tighten the check for "PMI in guest" to reduce false positives if an NMI arrives in the host while KVM is handling an IRQ VM-Exit.
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.