@@ -868,19 +868,10 @@ int vec_set_vector_length(struct task_struct *task, enum vec_type type,
task->thread.fp_type = FP_STATE_FPSIMD;
}
- if (system_supports_sme()) {
- if (type == ARM64_VEC_SME ||
- !(task->thread.svcr & (SVCR_SM_MASK | SVCR_ZA_MASK))) {
- /*
- * We are changing the SME VL or weren't using
- * SME anyway, discard the state and force a
- * reallocation.
- */
- task->thread.svcr &= ~(SVCR_SM_MASK |
- SVCR_ZA_MASK);
- clear_tsk_thread_flag(task, TIF_SME);
- free_sme = true;
- }
+ if (system_supports_sme() && type == ARM64_VEC_SME) {
+ task->thread.svcr &= ~(SVCR_SM_MASK | SVCR_ZA_MASK);
+ clear_tsk_thread_flag(task, TIF_SME);
+ free_sme = true;
}
if (task == current)
When a task's SVE vector length (NSVL) is changed, and the task happens to have SVCR.{SM,ZA}=={0,0}, vec_set_vector_length() opportunistically frees the task's sme_state and clears TIF_SME. The opportunistic freeing was added with no rationale in commit: d4d5be94a8787242 ("arm64/fpsimd: Ensure SME storage is allocated after SVE VL changes") That commit fixed an unrelated problem where the task's sve_state was freed while it could be used to store streaming mode register state, where the fix was to re-allocate the task's sve_state. There is no need to free and/or reallocate the task's sme_state when the SVE vector length changes, and there is no need to clear TIF_SME. Given the SME vector length (SVL) doesn't change, the task's sme_state remains correctly sized. Remove the unnecessary opportunistic freeing of the task's sme_state when the task's SVE vector length is changed. The task's sme_state is still freed when the SME vector length is changed. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Will Deacon <will@kernel.org> Reviewed-by: Mark Brown <broonie@kernel.org> --- arch/arm64/kernel/fpsimd.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-)