sched: Define and initialize a flag to identify valid PASID in the task

mainline inclusion
from mainline-v5.18
commit a3d29e82
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO
CVE: NA

Intel-SIG: commit a3d29e82 sched: Define and initialize a flag to identify valid PASID in the task.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

--------------------------------

Add a new single bit field to the task structure to track whether this task
has initialized the IA32_PASID MSR to the mm's PASID.

Initialize the field to zero when creating a new task with fork/clone.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Co-developed-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NTony Luck <tony.luck@intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-8-fenghua.yu@intel.comSigned-off-by: NXiaochen Shen <xiaochen.shen@intel.com>

include/linux/sched.h

@@ -872,6 +872,9 @@ struct task_struct {
 	/* Stalled due to lack of memory */
 	unsigned			in_memstall:1;
 #endif
+#ifdef CONFIG_IOMMU_SVA
+	unsigned			pasid_activated:1;
+#endif
 
 	unsigned long			atomic_flags; /* Flags requiring atomic access. */
 

kernel/fork.c

@@ -963,6 +963,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	tsk->use_memdelay = 0;
 #endif
 
+#ifdef CONFIG_IOMMU_SVA
+	tsk->pasid_activated = 0;
+#endif
+
 #ifdef CONFIG_MEMCG
 	tsk->active_memcg = NULL;
 #endif