[PATCH v3 04/11] kernel/fork: Initialize mm's PASID

[Fenghua Yu]

A new mm doesn't have a PASID yet when it's created. Initialize
the mm's PASID on fork() or for init_mm to INVALID_IOASID (-1).

Suggested-by: Dave Hansen <dave.han...@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua...@intel.com>
Reviewed-by: Tony Luck <tony.l...@intel.com>
---
v2:
- Change condition to more accurate CONFIG_IOMMU_SVA (Jacob)

 include/linux/sched/mm.h | 10 ++++++++++
 kernel/fork.c            | 10 ++--------
 mm/init-mm.c             |  4 ++++
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index aa5f09ca5bcf..c74d1edbac2f 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -8,6 +8,7 @@
 #include <linux/mm_types.h>
 #include <linux/gfp.h>
 #include <linux/sync_core.h>
+#include <linux/ioasid.h>
 
 /*
  * Routines for handling mm_structs
@@ -433,4 +434,13 @@ static inline void membarrier_update_current_mm(struct 
mm_struct *next_mm)
 }
 #endif
 
+#ifdef CONFIG_IOMMU_SVA
+static inline void mm_pasid_init(struct mm_struct *mm)
+{
+       mm->pasid = INVALID_IOASID;
+}
+#else
+static inline void mm_pasid_init(struct mm_struct *mm) {}
+#endif
+
 #endif /* _LINUX_SCHED_MM_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 6ee7551d3bd2..deacd2c17a7f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -97,6 +97,7 @@
 #include <linux/scs.h>
 #include <linux/io_uring.h>
 #include <linux/bpf.h>
+#include <linux/sched/mm.h>
 
 #include <asm/pgalloc.h>
 #include <linux/uaccess.h>
@@ -1019,13 +1020,6 @@ static void mm_init_owner(struct mm_struct *mm, struct 
task_struct *p)
 #endif
 }
 
-static void mm_init_pasid(struct mm_struct *mm)
-{
-#ifdef CONFIG_IOMMU_SVA
-       mm->pasid = INIT_PASID;
-#endif
-}
-
 static void mm_init_uprobes_state(struct mm_struct *mm)
 {
 #ifdef CONFIG_UPROBES
@@ -1054,7 +1048,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, 
struct task_struct *p,
        mm_init_cpumask(mm);
        mm_init_aio(mm);
        mm_init_owner(mm, p);
-       mm_init_pasid(mm);
+       mm_pasid_init(mm);
        RCU_INIT_POINTER(mm->exe_file, NULL);
        mmu_notifier_subscriptions_init(mm);
        init_tlb_flush_pending(mm);
diff --git a/mm/init-mm.c b/mm/init-mm.c
index b4a6f38fb51d..fbe7844d0912 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -10,6 +10,7 @@
 
 #include <linux/atomic.h>
 #include <linux/user_namespace.h>
+#include <linux/ioasid.h>
 #include <asm/mmu.h>
 
 #ifndef INIT_MM_CONTEXT
@@ -38,6 +39,9 @@ struct mm_struct init_mm = {
        .mmlist         = LIST_HEAD_INIT(init_mm.mmlist),
        .user_ns        = &init_user_ns,
        .cpu_bitmap     = CPU_BITS_NONE,
+#ifdef CONFIG_IOMMU_SVA
+       .pasid          = INVALID_IOASID,
+#endif
        INIT_MM_CONTEXT(init_mm)
 };
 
-- 
2.35.0

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