Merge tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd

Pull iommufd updates from Jason Gunthorpe:
 "This is a pretty consequential cycle for iommufd, though this pull is
  not too big. It is based on a shared branch with VFIO that introduces
  VFIO_DEVICE_FEATURE_DMA_BUF a DMABUF exporter for VFIO device's MMIO
  PCI BARs. This was a large multiple series journey over the last year
  and a half.

  Based on that work IOMMUFD gains support for VFIO DMABUF's in its
  existing IOMMU_IOAS_MAP_FILE, which closes the last major gap to
  support PCI peer to peer transfers within VMs.

  In Joerg's iommu tree we have the "generic page table" work which aims
  to consolidate all the duplicated page table code in every iommu
  driver into a single algorithm. This will be used by iommufd to
  implement unique page table operations to start adding new features
  and improve performance.

  In here:

   - Expand IOMMU_IOAS_MAP_FILE to accept a DMABUF exported from VFIO.
     This is the first step to broader DMABUF support in iommufd, right
     now it only works with VFIO. This closes the last functional gap
     with classic VFIO type 1 to safely support PCI peer to peer DMA by
     mapping the VFIO device's MMIO into the IOMMU.

   - Relax SMMUv3 restrictions on nesting domains to better support
     qemu's sequence to have an identity mapping before the vSID is
     established"

* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd:
  iommu/arm-smmu-v3-iommufd: Allow attaching nested domain for GBPA cases
  iommufd/selftest: Add some tests for the dmabuf flow
  iommufd: Accept a DMABUF through IOMMU_IOAS_MAP_FILE
  iommufd: Have iopt_map_file_pages convert the fd to a file
  iommufd: Have pfn_reader process DMABUF iopt_pages
  iommufd: Allow MMIO pages in a batch
  iommufd: Allow a DMABUF to be revoked
  iommufd: Do not map/unmap revoked DMABUFs
  iommufd: Add DMABUF to iopt_pages
  vfio/pci: Add vfio_pci_dma_buf_iommufd_map()

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
index 6698f540bdac..d4d0f7d08c53 100644
--- a/drivers/vfio/pci/vfio_pci_dmabuf.c
+++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
@@ -82,6 +82,40 @@ static const struct dma_buf_ops vfio_pci_dmabuf_ops = {
 	.release = vfio_pci_dma_buf_release,
 };
 
+/*
+ * This is a temporary "private interconnect" between VFIO DMABUF and iommufd.
+ * It allows the two co-operating drivers to exchange the physical address of
+ * the BAR. This is to be replaced with a formal DMABUF system for negotiated
+ * interconnect types.
+ *
+ * If this function succeeds the following are true:
+ *  - There is one physical range and it is pointing to MMIO
+ *  - When move_notify is called it means revoke, not move, vfio_dma_buf_map
+ *    will fail if it is currently revoked
+ */
+int vfio_pci_dma_buf_iommufd_map(struct dma_buf_attachment *attachment,
+				 struct dma_buf_phys_vec *phys)
+{
+	struct vfio_pci_dma_buf *priv;
+
+	dma_resv_assert_held(attachment->dmabuf->resv);
+
+	if (attachment->dmabuf->ops != &vfio_pci_dmabuf_ops)
+		return -EOPNOTSUPP;
+
+	priv = attachment->dmabuf->priv;
+	if (priv->revoked)
+		return -ENODEV;
+
+	/* More than one range to iommufd will require proper DMABUF support */
+	if (priv->nr_ranges != 1)
+		return -EOPNOTSUPP;
+
+	*phys = priv->phys_vec[0];
+	return 0;
+}
+EXPORT_SYMBOL_FOR_MODULES(vfio_pci_dma_buf_iommufd_map, "iommufd");
+
 int vfio_pci_core_fill_phys_vec(struct dma_buf_phys_vec *phys_vec,
 				struct vfio_region_dma_range *dma_ranges,
 				size_t nr_ranges, phys_addr_t start,