On Wed, May 09, 2018 at 05:12:55PM +0100, Dave P Martin wrote: > In preparation for optimising the way KVM manages switching the > guest and host FPSIMD state, it is necessary to provide a means for > code outside arch/arm64/kernel/fpsimd.c to restore the user trap > configuration for SVE correctly for the current task. > > Rather than requiring external code to duplicate the maintenance > explicitly, this patch wraps moves the trap maintenenace to > fpsimd_bind_to_cpu(), since it is logically part of the work of > associating the current task with the cpu. > > Because fpsimd_bind_to_cpu() is rather a cryptic name to publish > alongside fpsimd_bind_state_to_cpu(), the former function is > renamed to fpsimd_bind_task_to_cpu() to make its purpose more > explicit. > > This patch makes appropriate changes to ensure that > fpsimd_bind_task_to_cpu() is always called alongside > task_fpsimd_load(), so that the trap maintenance continues to be > done in every situation where it was done prior to this patch. > > As a side-effect, the metadata updates done by > fpsimd_bind_task_to_cpu() now change from conditional to > unconditional in the "already bound" case of sigreturn. This is > harmless, and a couple of extra stores on this slow path will not > impact performance. I consider this a reasonable price to pay for > a slightly cleaner interface. > > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx> _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
