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Julien Grall
e98edccb94
On Arm64, system registers are always 64-bit including SCTLR_EL1.
However, Xen is assuming this is 32-bit because earlier revision of
Armv8 had the top 32-bit RES0 (see ARM DDI0595.b).
>From Armv8.5, some bits in [63:32] will be defined and allowed to be
modified by the guest. So we would effectively reset those bits to 0
after each context switch. This means the guest may not function
correctly afterwards.
Rather than resetting to 0 the bits [63:32], preserve them across
context switch.
Note that the corresponding register on Arm32 (i.e SCTLR) is always
32-bit. So we need to use register_t anywhere we deal the SCTLR{,_EL1}.
Outside interface is switched to use 64-bit to allow ABI compatibility
between 32-bit and 64-bit.
[Stefano: fix typo in commit message]
Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
Reviewed-by: Volodymyr Babchuk <volodymyr.babchuk@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>