1 files changed, 16 insertions, 11 deletions

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index fc9187b6fae7..e3afb610f2ad 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -530,31 +530,35 @@ static void ssb_select_mitigation()
 
 #undef pr_fmt
 
-static int ssb_prctl_set(unsigned long ctrl)
+static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
 {
-        bool rds = !!test_tsk_thread_flag(current, TIF_RDS);
+        bool rds = !!test_tsk_thread_flag(task, TIF_RDS);
 
         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL)
                 return -ENXIO;
 
         if (ctrl == PR_SPEC_ENABLE)
-                clear_tsk_thread_flag(current, TIF_RDS);
+                clear_tsk_thread_flag(task, TIF_RDS);
         else
-                set_tsk_thread_flag(current, TIF_RDS);
+                set_tsk_thread_flag(task, TIF_RDS);
 
-        if (rds != !!test_tsk_thread_flag(current, TIF_RDS))
+        /*
+         * If being set on non-current task, delay setting the CPU
+         * mitigation until it is next scheduled.
+         */
+        if (task == current && rds != !!test_tsk_thread_flag(task, TIF_RDS))
                 speculative_store_bypass_update();
 
         return 0;
 }
 
-static int ssb_prctl_get(void)
+static int ssb_prctl_get(struct task_struct *task)
 {
         switch (ssb_mode) {
         case SPEC_STORE_BYPASS_DISABLE:
                 return PR_SPEC_DISABLE;
         case SPEC_STORE_BYPASS_PRCTL:
-                if (test_tsk_thread_flag(current, TIF_RDS))
+                if (test_tsk_thread_flag(task, TIF_RDS))
                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
         default:
@@ -564,24 +568,25 @@ static int ssb_prctl_get(void)
         }
 }
 
-int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
+                             unsigned long ctrl)
 {
         if (ctrl != PR_SPEC_ENABLE && ctrl != PR_SPEC_DISABLE)
                 return -ERANGE;
 
         switch (which) {
         case PR_SPEC_STORE_BYPASS:
-                return ssb_prctl_set(ctrl);
+                return ssb_prctl_set(task, ctrl);
         default:
                 return -ENODEV;
         }
 }
 
-int arch_prctl_spec_ctrl_get(unsigned long which)
+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
 {
         switch (which) {
         case PR_SPEC_STORE_BYPASS:
-                return ssb_prctl_get();
+                return ssb_prctl_get(task);
         default:
                 return -ENODEV;
         }