Hostos devel #29
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Hostos devel #29
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…pt remapping is enabled" This reverts commit fb71dea.
The vfio_info_add_capability() helper requires the caller to pass a capability ID, which it then uses to fill in header fields, assuming hard coded versions. This makes for an awkward and rigid interface. The only thing we want this helper to do is allocate sufficient space in the caps buffer and chain this capability into the list. Reduce it to that simple task. Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com> Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> (cherry picked from commit dda01f7) Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
By default VFIO disables mapping of MSIX BAR to the userspace as the userspace may program it in a way allowing spurious interrupts; instead the userspace uses the VFIO_DEVICE_SET_IRQS ioctl. In order to eliminate guessing from the userspace about what is mmapable, VFIO also advertises a sparse list of regions allowed to mmap. This works fine as long as the system page size equals to the MSIX alignment requirement which is 4KB. However with a bigger page size the existing code prohibits mapping non-MSIX parts of a page with MSIX structures so these parts have to be emulated via slow reads/writes on a VFIO device fd. If these emulated bits are accessed often, this has serious impact on performance. This allows mmap of the entire BAR containing MSIX vector table. This removes the sparse capability for PCI devices as it becomes useless. As the userspace needs to know for sure whether mmapping of the MSIX vector containing data can succeed, this adds a new capability - VFIO_REGION_INFO_CAP_MSIX_MAPPABLE - which explicitly tells the userspace that the entire BAR can be mmapped. This does not touch the MSIX mangling in the BAR read/write handlers as we are doing this just to enable direct access to non MSIX registers. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> [aw - fixup whitespace, trim function name] Signed-off-by: Alex Williamson <alex.williamson@redhat.com> (cherry picked from commit a32295c) Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
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These supersede the original MSIX BAR mapping patches from Yongji. When applied, I'll push the QEMU part of it.