[PATCH 0/3] virtio-iommu on non-devicetree platforms

Jean-Philippe Brucker
Fri, 14 Feb 2020 16:04:10 -0000

Add topology description to the virtio-iommu driver and enable x86
platforms. Since the RFC [1] I've mostly given up on ACPI tables, since
the internal discussions seem to have reached a dead end. The built-in
topology description presented here isn't ideal, but it is simple to
implement and doesn't impose a dependency on ACPI or device-tree, which
can be beneficial to lightweight hypervisors.

The built-in description is an array in the virtio config space. The
driver parses the config space early and postpones endpoint probe until
the virtio-iommu device is ready. Each element in the array describes
either a PCI range or a single MMIO endpoint, and their associated
endpoint IDs:

struct virtio_iommu_topo_pci_range {
	__le16 type;			/* 1: PCI range */
	__le16 hierarchy;		/* PCI domain number */
	__le16 requester_start;		/* First BDF */
	__le16 requester_end;		/* Last BDF */
	__le32 endpoint_start;		/* First endpoint ID */
};

struct virtio_iommu_topo_endpoint {
	__le16 type;			/* 2: Endpoint */
	__le16 reserved;		/* 0 */
	__le32 endpoint;		/* Endpoint ID */
	__le64 address;			/* First MMIO address */
};

You can find the QEMU patches based on Eric's latest device on my
virtio-iommu/devel branch [2]. I test on both x86 q35, and aarch64 virt
machine with edk2.

[1] https://lore.kernel.org/linux-iommu/20191122105000.800410-1-jean-philippe at
linaro.org/
[2] https://jpbrucker.net/git/qemu virtio-iommu/devel

Jean-Philippe Brucker (3):
  iommu/virtio: Add topology description to virtio-iommu config space
  PCI: Add DMA configuration for virtual platforms
  iommu/virtio: Enable x86 support

 MAINTAINERS                           |   2 +
 drivers/iommu/Kconfig                 |  13 +-
 drivers/iommu/Makefile                |   1 +
 drivers/iommu/virtio-iommu-topology.c | 343 ++++++++++++++++++++++++++
 drivers/iommu/virtio-iommu.c          |   3 +
 drivers/pci/pci-driver.c              |   5 +
 include/linux/virt_iommu.h            |  19 ++
 include/uapi/linux/virtio_iommu.h     |  26 ++
 8 files changed, 411 insertions(+), 1 deletion(-)
 create mode 100644 drivers/iommu/virtio-iommu-topology.c
 create mode 100644 include/linux/virt_iommu.h

--
2.25.0