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ARM v8.3 introduces a new bit in the HCR_EL2, which is the NV bit. When this bit is set, accessing EL2 registers in EL1 traps to EL2. In addition, executing the following instructions in EL1 will trap to EL2: tlbi, at, eret, and msr/mrs instructions to access SP_EL1. Most of the instructions that trap to EL2 with the NV bit were undef at EL1 prior to ARM v8.3. The only instruction that was not undef is eret. This patch sets up a handler for EL2 registers and SP_EL1 register accesses at EL1. The host hypervisor keeps those register values in memory, and will emulate their behavior. This patch doesn't set the NV bit yet. It will be set in a later patch once nested virtualization support is completed. Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Jintack Lim <jintack.lim@linaro.org> [maz: EL2_REG() macros] Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20230209175820.1939006-9-maz@kernel.org 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.