[PATCH v2 07/11] sched: Define and initialize a flag to identify valid PASID in the task

[Fenghua Yu <fenghua.yu@intel.com>]

From: Peter Zijlstra <peterz@infradead.org>

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: Peter Zijlstra <peterz@infradead.org>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
v2:
- Change condition to more accurate CONFIG_IOMMU_SVA (Jacob)

 include/linux/sched.h | 3 +++
 kernel/fork.c         | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 78c351e35fec..41a0b5703f94 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -933,6 +933,9 @@ struct task_struct {
 	/* Recursion prevention for eventfd_signal() */
 	unsigned			in_eventfd_signal:1;
 #endif
+#ifdef CONFIG_IOMMU_SVA
+	unsigned			pasid_activated:1;
+#endif
 
 	unsigned long			atomic_flags; /* Flags requiring atomic access. */
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 3adad225cc09..cd297926b6f2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -967,6 +967,10 @@ 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
-- 
2.34.1