arm64/sve: Rework SVE trap access to use TIF_SVE_NEEDS_FLUSH
SVE state will be flushed on the first SVE access trap. At the moment,
the SVE state will be generated from the FPSIMD state in software and
then loaded in memory.
It is possible to use the newly introduce flag TIF_SVE_NEEDS_FLUSH to
avoid a lot of memory access.
If the FPSIMD state is in memory, the SVE state will be loaded on return
to userspace from the FPSIMD state.
If the FPSIMD state is loaded, then we need to set the vector-length
before relying on return to userspace to flush the SVE registers. This
is because the vector length is only set when loading from memory. We
also need to rebind the task to the CPU so the newly allocated SVE state
is used when the task is saved.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
3 files changed
