1 files changed, 24 insertions, 15 deletions

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 062b21f30f94..ad3dd34a83cf 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -180,7 +180,7 @@ static void __get_cpu_fpsimd_context(void)
  */
 static void get_cpu_fpsimd_context(void)
 {
-	preempt_disable();
+	local_bh_disable();
 	__get_cpu_fpsimd_context();
 }
 
@@ -201,7 +201,7 @@ static void __put_cpu_fpsimd_context(void)
 static void put_cpu_fpsimd_context(void)
 {
 	__put_cpu_fpsimd_context();
-	preempt_enable();
+	local_bh_enable();
 }
 
 static bool have_cpu_fpsimd_context(void)
@@ -285,7 +285,7 @@ static void task_fpsimd_load(void)
 	WARN_ON(!system_supports_fpsimd());
 	WARN_ON(!have_cpu_fpsimd_context());
 
-	if (system_supports_sve() && test_thread_flag(TIF_SVE))
+	if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE))
 		sve_load_state(sve_pffr(&current->thread),
 			       &current->thread.uw.fpsimd_state.fpsr,
 			       sve_vq_from_vl(current->thread.sve_vl) - 1);
@@ -307,7 +307,8 @@ static void fpsimd_save(void)
 	WARN_ON(!have_cpu_fpsimd_context());
 
 	if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
-		if (system_supports_sve() && test_thread_flag(TIF_SVE)) {
+		if (IS_ENABLED(CONFIG_ARM64_SVE) &&
+		    test_thread_flag(TIF_SVE)) {
 			if (WARN_ON(sve_get_vl() != last->sve_vl)) {
 				/*
 				 * Can't save the user regs, so current would
@@ -926,9 +927,8 @@ void fpsimd_release_task(struct task_struct *dead_task)
  * Trapped SVE access
  *
  * Storage is allocated for the full SVE state, the current FPSIMD
- * register contents are migrated across, and TIF_SVE is set so that
- * the SVE access trap will be disabled the next time this task
- * reaches ret_to_user.
+ * register contents are migrated across, and the access trap is
+ * disabled.
  *
  * TIF_SVE should be clear on entry: otherwise, fpsimd_restore_current_state()
  * would have disabled the SVE access trap for userspace during
@@ -946,15 +946,24 @@ void do_sve_acc(unsigned int esr, struct pt_regs *regs)
 
 	get_cpu_fpsimd_context();
 
-	fpsimd_save();
-
-	/* Force ret_to_user to reload the registers: */
-	fpsimd_flush_task_state(current);
-
-	fpsimd_to_sve(current);
 	if (test_and_set_thread_flag(TIF_SVE))
 		WARN_ON(1); /* SVE access shouldn't have trapped */
 
+	/*
+	 * Convert the FPSIMD state to SVE, zeroing all the state that
+	 * is not shared with FPSIMD. If (as is likely) the current
+	 * state is live in the registers then do this there and
+	 * update our metadata for the current task including
+	 * disabling the trap, otherwise update our in-memory copy.
+	 */
+	if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
+		sve_set_vq(sve_vq_from_vl(current->thread.sve_vl) - 1);
+		sve_flush_live();
+		fpsimd_bind_task_to_cpu();
+	} else {
+		fpsimd_to_sve(current);
+	}
+
 	put_cpu_fpsimd_context();
 }
 
@@ -1092,7 +1101,7 @@ void fpsimd_preserve_current_state(void)
 void fpsimd_signal_preserve_current_state(void)
 {
 	fpsimd_preserve_current_state();
-	if (system_supports_sve() && test_thread_flag(TIF_SVE))
+	if (test_thread_flag(TIF_SVE))
 		sve_to_fpsimd(current);
 }
 
@@ -1181,7 +1190,7 @@ void fpsimd_update_current_state(struct user_fpsimd_state const *state)
 	get_cpu_fpsimd_context();
 
 	current->thread.uw.fpsimd_state = *state;
-	if (system_supports_sve() && test_thread_flag(TIF_SVE))
+	if (test_thread_flag(TIF_SVE))
 		fpsimd_to_sve(current);
 
 	task_fpsimd_load();