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Access to the AMU counters should be disabled by default in kvm guests, as information from the counters might reveal activity in other guests or activity on the host. Therefore, disable access to AMU registers from EL0 and EL1 in kvm guests by: - Hiding the presence of the extension in the feature register (SYS_ID_AA64PFR0_EL1) on the VCPU. - Disabling access to the AMU registers before switching to the guest. - Trapping accesses and injecting an undefined instruction into the guest. Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Acked-by: Marc Zyngier <maz@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Julien Thierry <julien.thierry.kdev@gmail.com> Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <maz@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.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.