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@infradead.org>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-8-fenghua.yu@intel.com

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75ba8aa..4e5de3a 100644 (file)
--- 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 (file)
--- 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