3 files changed, 14 insertions, 4 deletions

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index e2f575dbdddd..c6fddb005dc2 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -107,6 +107,7 @@ struct thread_struct {
         struct fpsimd_state     fpsimd_state;
         void                    *sve_state;     /* SVE registers, if any */
         unsigned int            sve_vl;         /* SVE vector length */
+        unsigned int            sve_vl_onexec;  /* SVE vl after next exec */
         unsigned long           fault_address;  /* fault info */
         unsigned long           fault_code;     /* ESR_EL1 value */
         struct debug_info       debug;          /* debugging */
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 92b7b48576c8..eb431286bacd 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -95,6 +95,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_SINGLESTEP          21
 #define TIF_32BIT               22      /* 32bit process */
 #define TIF_SVE                 23      /* Scalable Vector Extension in use */
+#define TIF_SVE_VL_INHERIT      24      /* Inherit sve_vl_onexec across exec */
 
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 000b5f9215c6..c7531b85b303 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -111,6 +111,9 @@
  */
 static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
 
+/* Default VL for tasks that don't set it explicitly: */
+static int sve_default_vl = SVE_VL_MIN;
+
 /*
  * Call __sve_free() directly only if you know task can't be scheduled
  * or preempted.
@@ -474,15 +477,20 @@ void fpsimd_flush_thread(void)
                  * If a bug causes this to go wrong, we make some noise and
                  * try to fudge thread.sve_vl to a safe value here.
                  */
-                vl = current->thread.sve_vl;
-
-                if (vl == 0)
-                        vl = SVE_VL_MIN;
+                vl = current->thread.sve_vl_onexec ?
+                        current->thread.sve_vl_onexec : sve_default_vl;
 
                 if (WARN_ON(!sve_vl_valid(vl)))
                         vl = SVE_VL_MIN;
 
                 current->thread.sve_vl = vl;
+
+                /*
+                 * If the task is not set to inherit, ensure that the vector
+                 * length will be reset by a subsequent exec:
+                 */
+                if (!test_thread_flag(TIF_SVE_VL_INHERIT))
+                        current->thread.sve_vl_onexec = 0;
         }
 
         set_thread_flag(TIF_FOREIGN_FPSTATE);