[PATCH v4 07/12] mm: Define pasid in mm

[Fenghua Yu]

PASID is shared by all threads in a process. So the logical place to keep
track of it is in the "mm". Both ARM and X86 need to use the PASID in the
"mm".

Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
---
v4:
- Change PASID type to u32 (Christoph)

v3:
- Change CONFIG_PCI_PASID to CONFIG_IOMMU_SUPPORT because non-PCI device
  can have PASID in ARM (Jean)

v2:
- This new patch moves "pasid" from x86 specific mm_context_t to generic
  struct mm_struct per Christopher's comment: https://lore.kernel.org/linux-iommu/20200414170252.714402-1-jean-philippe@xxxxxxxxxx/T/#mb57110ffe1aaa24750eeea4f93b611f0d1913911
- Jean-Philippe Brucker released a virtually same patch. I still put this
  patch in the series for better review. The upstream kernel only needs one
  of the two patches eventually.
https://lore.kernel.org/linux-iommu/20200519175502.2504091-2-jean-philippe@xxxxxxxxxx/
- Change CONFIG_IOASID to CONFIG_PCI_PASID (Ashok)

 include/linux/mm_types.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 64ede5f150dc..d61285cfe027 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -538,6 +538,10 @@ struct mm_struct {
 		atomic_long_t hugetlb_usage;
 #endif
 		struct work_struct async_put_work;
+
+#ifdef CONFIG_IOMMU_SUPPORT
+		u32 pasid;
+#endif
 	} __randomize_layout;
 
 	/*
-- 
2.19.1