tree 0037527ee4af84233f61cb8efba847eef1b618c9
parent 9da7558ca9a7ca487e572ede57c4fa03294a70b7
author Julien Grall <julien.grall@arm.com> 1560442616 +0100
committer Mark Brown <broonie@kernel.org> 1604685422 +0000
gpgsig -----BEGIN PGP SIGNATURE-----
 
 iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl+ljm4ACgkQJNaLcl1U
 h9AIagf/eQyNApxgJiynDs6jllnhGzhVuUn5CRk7wjrHvOn0BaU01O3Ws2huSE1N
 gp82+JGCy2KN8sr7kAflgrkkL31e7TjZmHhFjgN/AV5vckQ2QnlXBWC0itWolGZ9
 Q+dGhCHP7HBDywc5+S0UpkZehcvrVT3QY3Jvyo6TJQXXF+DeGKRsU8C6W+7F1APM
 EOVZ7sCUthf8fzBSUSIO4o1ToX3221qVTAnOXA2HBmEJpiIDlvzgwsRhkHGIMuLq
 D/i0UbN9rtqUhSeAvKYdsx1ptciUd+ECotw4kI3VG9do53xMHf532OJ8kn0PGyFu
 ECqGxNJMThRJ15kkmN2JNwe4ywVACA==
 =QgVG
 -----END PGP SIGNATURE-----

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>