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authorFenghua Yu <fenghua.yu@intel.com>2022-02-07 15:02:48 -0800
committerBorislav Petkov <bp@suse.de>2022-02-15 11:31:35 +0100
commit701fac40384f07197b106136012804c3cae0b3de (patch)
tree1637d8cc005e07c28f7357b8a6dd8c538c9f5967 /include/linux/sched
parenta6cbd44093ef305b02ad5f80ed54abf0148a696c (diff)
iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
PASIDs are process-wide. It was attempted to use refcounted PASIDs to free them when the last thread drops the refcount. This turned out to be complex and error prone. Given the fact that the PASID space is 20 bits, which allows up to 1M processes to have a PASID associated concurrently, PASID resource exhaustion is not a realistic concern. Therefore, it was decided to simplify the approach and stick with lazy on demand PASID allocation, but drop the eager free approach and make an allocated PASID's lifetime bound to the lifetime of the process. Get rid of the refcounting mechanisms and replace/rename the interfaces to reflect this new approach. [ bp: Massage commit message. ] Suggested-by: Dave Hansen <dave.hansen@linux.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: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Joerg Roedel <jroedel@suse.de> Link: https://lore.kernel.org/r/20220207230254.3342514-6-fenghua.yu@intel.com
Diffstat (limited to 'include/linux/sched')
-rw-r--r--include/linux/sched/mm.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index c74d1edbac2f..a80356e9dc69 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -439,8 +439,24 @@ static inline void mm_pasid_init(struct mm_struct *mm)
{
mm->pasid = INVALID_IOASID;
}
+
+/* Associate a PASID with an mm_struct: */
+static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
+{
+ mm->pasid = pasid;
+}
+
+static inline void mm_pasid_drop(struct mm_struct *mm)
+{
+ if (pasid_valid(mm->pasid)) {
+ ioasid_free(mm->pasid);
+ mm->pasid = INVALID_IOASID;
+ }
+}
#else
static inline void mm_pasid_init(struct mm_struct *mm) {}
+static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid) {}
+static inline void mm_pasid_drop(struct mm_struct *mm) {}
#endif
#endif /* _LINUX_SCHED_MM_H */