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The performance monitoring infrastructure, perfmon, is to support collection of information about key events occurring during operation of the remapping hardware, to aid performance tuning and debug. Each remapping hardware unit has capability registers that indicate support for performance monitoring features and enumerate the capabilities. Add alloc_iommu_pmu() to retrieve IOMMU perfmon capability information for each iommu unit. The information is stored in the iommu->pmu data structure. Capability registers are read-only, so it's safe to prefetch and store them in the pmu structure. This could avoid unnecessary VMEXIT when this code is running in the virtualization environment. Add free_iommu_pmu() to free the saved capability information when freeing the iommu unit. Add a kernel config option for the IOMMU perfmon feature. Unless a user explicitly uses the perf tool to monitor the IOMMU perfmon event, there isn't any impact for the existing IOMMU. Enable it by default. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20230128200428.1459118-3-kan.liang@linux.intel.com Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
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.