Commit 45fd8698 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64/fpsimd: Remove redundant SVE trap manipulation 



When task_fpsimd_load() loads the saved FPSIMD/SVE/SME state, it
configures EL0 SVE traps by calling sve_user_{enable,disable}(). This is
unnecessary, and this is suspicious/confusing as task_fpsimd_load() does
not configure EL0 SME traps.

All calls to task_fpsimd_load() are followed by a call to
fpsimd_bind_task_to_cpu(), where the latter configures traps for SVE and
SME dependent upon the current values of TIF_SVE and TIF_SME, overriding
any trap configuration performed by task_fpsimd_load().

The calls to sve_user_{enable,disable}() calls in task_fpsimd_load()
have been redundant (though benign) since they were introduced in
commit:

  a0136be4 ("arm64/fpsimd: Load FP state based on recorded data type")

Remove the unnecessary and confusing SVE trap manipulation.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250409164010.3480271-4-mark.rutland@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 61db0e0b

arch/arm64/kernel/fpsimd.c

+3 −5
Original line number Diff line number Diff line
@@ -366,13 +366,11 @@ static void task_fpsimd_load(void) 
		switch (current->thread.fp_type) {

		case FP_STATE_FPSIMD:

			/* Stop tracking SVE for this task until next use. */

			if (test_and_clear_thread_flag(TIF_SVE))

				sve_user_disable();

			clear_thread_flag(TIF_SVE);

			break;

		case FP_STATE_SVE:

			if (!thread_sm_enabled(&current->thread) &&

			    !WARN_ON_ONCE(!test_and_set_thread_flag(TIF_SVE)))

				sve_user_enable();

			if (!thread_sm_enabled(&current->thread))

				WARN_ON_ONCE(!test_and_set_thread_flag(TIF_SVE));



			if (test_thread_flag(TIF_SVE))

				sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1);