[tip: x86/pasid] sched: Define and initialize a flag to identify valid PASID in the task

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the x86/pasid branch of tip:

Commit-ID:     a3d29e8291b622780eb6e4e3eeaf2b24ec78fd43
Gitweb:        https://git.kernel.org/tip/a3d29e8291b622780eb6e4e3eeaf2b24ec78fd43
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Mon, 07 Feb 2022 15:02:50 -08:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Tue, 15 Feb 2022 11:31:43 +01:00

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

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@xxxxxxxxxxxxx>
Co-developed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220207230254.3342514-8-fenghua.yu@xxxxxxxxx
---
 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 75ba8aa..4e5de3a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -938,6 +938,9 @@ 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 c03c668..51fd1df 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -968,6 +968,10 @@ 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