arm64/fpsimd: SME no longer requires SVE register state

Now that we track the type of the stored register state separately to
what is active in the task, it is valid to have the FPSIMD register
state stored while in streaming mode. Remove the special case handling
for SME when setting FPSIMD register state.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221115094640.112848-7-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

Author: broonie

arch/arm64/kernel/fpsimd.c

@@ -815,8 +815,7 @@ void fpsimd_sync_to_sve(struct task_struct *task)
  */
 void sve_sync_to_fpsimd(struct task_struct *task)
 {
-	if (test_tsk_thread_flag(task, TIF_SVE) ||
-	    thread_sm_enabled(&task->thread))
+	if (task->thread.fp_type == FP_STATE_SVE)
 		sve_to_fpsimd(task);
 }
 

arch/arm64/kernel/ptrace.c

@@ -907,8 +907,6 @@ static int sve_set_common(struct task_struct *target,
 		ret = __fpr_set(target, regset, pos, count, kbuf, ubuf,
 				SVE_PT_FPSIMD_OFFSET);
 		clear_tsk_thread_flag(target, TIF_SVE);
-		if (type == ARM64_VEC_SME)
-			fpsimd_force_sync_to_sve(target);
 		target->thread.fp_type = FP_STATE_FPSIMD;
 		goto out;
 	}