On Tue, 11 Nov 2025 10:48:23 -0800 Alex Mastro <[email protected]> wrote:
> Not all IOMMUs support the same virtual address width as the processor, > for instance older Intel consumer platforms only support 39-bits of > IOMMU address space. On such platforms, using the virtual address as the > IOVA and mappings at the top of the address space both fail. > > VFIO and IOMMUFD have facilities for retrieving valid IOVA ranges, > VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE and IOMMU_IOAS_IOVA_RANGES, > respectively. These provide compatible arrays of ranges from which we > can construct a simple allocator. > > Use this new allocator in place of reusing the virtual address, and > incorporate the maximum supported IOVA into the limit testing. This > latter change doesn't test quite the same absolute end-of-address space > behavior but still seems to have some value. > > This series is based on Alex Williamson's "Incorporate IOVA range info" > [1] along with feedback from the discussion in David Matlack's "Skip > vfio_dma_map_limit_test if mapping returns -EINVAL" [2]. > > Given David's plans to split IOMMU concerns from devices as described > in [3], this series' home for `struct iova_allocator` and IOVA > range helpers are likely to be short lived, since they reside in > vfio_pci_device.c. I assume that the rework can move this functionality > to a more appropriate location next to other IOMMU-focused code, once > such a place exists. > > [1] https://lore.kernel.org/all/[email protected]/#t > [2] https://lore.kernel.org/all/[email protected]/ > [3] https://lore.kernel.org/all/[email protected]/ > > To: Alex Williamson <[email protected]> > To: David Matlack <[email protected]> > To: Shuah Khan <[email protected]> > To: Jason Gunthorpe <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Signed-off-by: Alex Mastro <[email protected]> > > Changes in v3: > - Update capability chain cycle detection > - Clarify the iova=vaddr commit message > - Link to v2: > https://lore.kernel.org/r/[email protected] Applied to vfio for-linus branch for v6.18. Thanks for the quick resolution on this! Alex
