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[v2,0/1] vfio: change spapr DMA window sizing operation

Message ID 20200630213823.1583764-1-drc@linux.vnet.ibm.com (mailing list archive)
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Series vfio: change spapr DMA window sizing operation | expand

Message

David Christensen June 30, 2020, 9:38 p.m. UTC
The SPAPR v2 IOMMU used on bare-metal PowerNV systems requires that a DMA
window be defined before mapping/unmapping memory.  The current VFIO code
dynamically resizes this DMA window every time a new memory request is
made, which requires that all existing memory be unmapped/remapped.
While this strategy worked in DPDK 17.11 and earlier where memory was
statically allocated during startup, it is potentially dangerous in DPDK
18.11 and later where memory can be allocated during runtime, temporarily
invalidating IOVA memory used by hardware.

This new code statically sizes the DMA window at startup, based on the
amount of memory installed in the system, avoiding the need to unmap
memory during runtime.

---
v2:
- Drop patch to wrap ppc64 code with ifdef's
- Add warning when external memory detected
- Change VA memory size detection to scan memseg list when setting DMA window
  for IOVA=VA
- Add explicit error message when attempting to map outside the DMA window

David Christensen (1):
  vfio: modify spapr iommu support to use static window sizing

 lib/librte_eal/linux/eal_vfio.c | 412 ++++++++++++++------------------
 1 file changed, 186 insertions(+), 226 deletions(-)

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2.18.2