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If a switch lacks ACS P2P Request Redirect, a device below the switch can bypass the IOMMU and DMA directly to other devices below the switch, so all the downstream devices must be in the same IOMMU group as the switch itself. The existing VFIO framework allows the portdrv driver to be bound to the bridge while its downstream devices are assigned to user space. The pci_dma_configure() marks the IOMMU group as containing only devices with kernel drivers that manage DMA. Avoid this default behavior for the portdrv driver in order for compatibility with the current VFIO usage. We achieve this by setting ".driver_managed_dma = true" in pci_driver structure. It is safe because the portdrv driver meets below criteria: - This driver doesn't use DMA, as you can't find any related calls like pci_set_master() or any kernel DMA API (dma_map_*() and etc.). - It doesn't use MMIO as you can't find ioremap() or similar calls. It's tolerant to userspace possibly also touching the same MMIO registers via P2P DMA access. Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Suggested-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20220418005000.897664-7-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de> |
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| .. | ||
| controller | ||
| endpoint | ||
| hotplug | ||
| msi | ||
| pcie | ||
| switch | ||
| access.c | ||
| ats.c | ||
| bus.c | ||
| ecam.c | ||
| host-bridge.c | ||
| iov.c | ||
| irq.c | ||
| Kconfig | ||
| Makefile | ||
| mmap.c | ||
| of.c | ||
| p2pdma.c | ||
| pci-acpi.c | ||
| pci-bridge-emul.c | ||
| pci-bridge-emul.h | ||
| pci-driver.c | ||
| pci-label.c | ||
| pci-mid.c | ||
| pci-pf-stub.c | ||
| pci-stub.c | ||
| pci-sysfs.c | ||
| pci.c | ||
| pci.h | ||
| probe.c | ||
| proc.c | ||
| quirks.c | ||
| remove.c | ||
| rom.c | ||
| search.c | ||
| setup-bus.c | ||
| setup-irq.c | ||
| setup-res.c | ||
| slot.c | ||
| syscall.c | ||
| vc.c | ||
| vgaarb.c | ||
| vpd.c | ||
| xen-pcifront.c | ||