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The number of PMU event counters is indicated in PMCR_EL0.N. For a vCPU with PMUv3 configured, the value is set to the same value as the current PE on every vCPU reset. Unless the vCPU is pinned to PEs that has the PMU associated to the guest from the initial vCPU reset, the value might be different from the PMU's PMCR_EL0.N on heterogeneous PMU systems. Fix this by setting the vCPU's PMCR_EL0.N to the PMU's PMCR_EL0.N value. Track the PMCR_EL0.N per guest, as only one PMU can be set for the guest (PMCR_EL0.N must be the same for all vCPUs of the guest), and it is convenient for updating the value. To achieve this, the patch introduces a helper, kvm_arm_pmu_get_max_counters(), that reads the maximum number of counters from the arm_pmu associated to the VM. Make the function global as upcoming patches will be interested to know the value while setting the PMCR.N of the guest from userspace. KVM does not yet support userspace modifying PMCR_EL0.N. The following patch will add support for that. Reviewed-by: Sebastian Ott <sebott@redhat.com> 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/20231020214053.2144305-5-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.