[PATCH v2 03/13] arm64/fpsimd: Remove redundant SVE trap manipulation

[Mark Rutland]

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:

  a0136be443d51803 ("arm64/fpsimd: Load FP state based on recorded data type")

Remove the unnecessary and confusing SVE trap manipulation.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Mark Brown <broonie at kernel.org>
Cc: Will Deacon <will at kernel.org>
Reviewed-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/kernel/fpsimd.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 1391a491f2226..757445d72e5b7 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -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);
-- 
2.30.2