VBox

Timestamp:

Feb 1, 2021 3:39:54 PM (4 years ago)

Author:

vboxsync

Message:

AMD IOMMU: bugref:9654 IOTLB cache bits.

File:

trunk/src/VBox/Devices/Bus/DevIommuAmd.cpp

-              r87506
+              r87510
 /**
+ * Checks whether two I/O walk results are physically contiguous.
+ * Checks whether two consecutive I/O page walk results translates to a physically
+ * contiguous region.
+ *
  * @returns @c true if they are physically contiguous, @c false otherwise.
 …
 /**
+ * Checks whether two I/O walk results form a "contiguous" access.
+ *
+ * When IOTLB caching is used, in addition to the translated system-physical
+ * addresses being physically contiguous, this function also verifies that the two
+ * pages are identical in terms of their page size and permissions.
+ *
+ * This is required to simplify IOTLB lookups for for large accesses (e.g. ATA
+ * device doing 65k transfers on Ubuntu 18.04 guests).
+ * Checks whether two consecutive I/O page walk results are part of a "contiguous"
+ * access.
+ *
+ * A "contiguous" access is when some range of I/O virtual addresses translate to a
+ * physically contiguous region of memory.
+ *
+ * When IOTLB caching is used, in addition to the translated addresses being
+ * physically contiguous, all pages in the access must have identical page sizes and
+ * I/O permissions. This is required to simplify IOTLB lookups for large accesses
+ * (e.g., ATA device doing 52k transfers on Ubuntu 18.04 guests).
+ *
  * @returns @c true if they are contiguous, @c false otherwise.

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