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-rw-r--r--Documentation/vfio.txt75
1 files changed, 69 insertions, 6 deletions
diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
index 8eda3635a17d..b9ca02370d46 100644
--- a/Documentation/vfio.txt
+++ b/Documentation/vfio.txt
@@ -167,17 +167,17 @@ group and can access them as follows:
int container, group, device, i;
struct vfio_group_status group_status =
{ .argsz = sizeof(group_status) };
- struct vfio_iommu_x86_info iommu_info = { .argsz = sizeof(iommu_info) };
- struct vfio_iommu_x86_dma_map dma_map = { .argsz = sizeof(dma_map) };
+ struct vfio_iommu_type1_info iommu_info = { .argsz = sizeof(iommu_info) };
+ struct vfio_iommu_type1_dma_map dma_map = { .argsz = sizeof(dma_map) };
struct vfio_device_info device_info = { .argsz = sizeof(device_info) };
/* Create a new container */
- container = open("/dev/vfio/vfio, O_RDWR);
+ container = open("/dev/vfio/vfio", O_RDWR);
if (ioctl(container, VFIO_GET_API_VERSION) != VFIO_API_VERSION)
/* Unknown API version */
- if (!ioctl(container, VFIO_CHECK_EXTENSION, VFIO_X86_IOMMU))
+ if (!ioctl(container, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU))
/* Doesn't support the IOMMU driver we want. */
/* Open the group */
@@ -193,7 +193,7 @@ group and can access them as follows:
ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
/* Enable the IOMMU model we want */
- ioctl(container, VFIO_SET_IOMMU, VFIO_X86_IOMMU)
+ ioctl(container, VFIO_SET_IOMMU, VFIO_TYPE1_IOMMU);
/* Get addition IOMMU info */
ioctl(container, VFIO_IOMMU_GET_INFO, &iommu_info);
@@ -229,7 +229,7 @@ group and can access them as follows:
irq.index = i;
- ioctl(device, VFIO_DEVICE_GET_IRQ_INFO, &reg);
+ ioctl(device, VFIO_DEVICE_GET_IRQ_INFO, &irq);
/* Setup IRQs... eventfds, VFIO_DEVICE_SET_IRQS */
}
@@ -283,6 +283,69 @@ a direct pass through for VFIO_DEVICE_* ioctls. The read/write/mmap
interfaces implement the device region access defined by the device's
own VFIO_DEVICE_GET_REGION_INFO ioctl.
+
+PPC64 sPAPR implementation note
+-------------------------------------------------------------------------------
+
+This implementation has some specifics:
+
+1) Only one IOMMU group per container is supported as an IOMMU group
+represents the minimal entity which isolation can be guaranteed for and
+groups are allocated statically, one per a Partitionable Endpoint (PE)
+(PE is often a PCI domain but not always).
+
+2) The hardware supports so called DMA windows - the PCI address range
+within which DMA transfer is allowed, any attempt to access address space
+out of the window leads to the whole PE isolation.
+
+3) PPC64 guests are paravirtualized but not fully emulated. There is an API
+to map/unmap pages for DMA, and it normally maps 1..32 pages per call and
+currently there is no way to reduce the number of calls. In order to make things
+faster, the map/unmap handling has been implemented in real mode which provides
+an excellent performance which has limitations such as inability to do
+locked pages accounting in real time.
+
+So 3 additional ioctls have been added:
+
+ VFIO_IOMMU_SPAPR_TCE_GET_INFO - returns the size and the start
+ of the DMA window on the PCI bus.
+
+ VFIO_IOMMU_ENABLE - enables the container. The locked pages accounting
+ is done at this point. This lets user first to know what
+ the DMA window is and adjust rlimit before doing any real job.
+
+ VFIO_IOMMU_DISABLE - disables the container.
+
+
+The code flow from the example above should be slightly changed:
+
+ .....
+ /* Add the group to the container */
+ ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
+
+ /* Enable the IOMMU model we want */
+ ioctl(container, VFIO_SET_IOMMU, VFIO_SPAPR_TCE_IOMMU)
+
+ /* Get addition sPAPR IOMMU info */
+ vfio_iommu_spapr_tce_info spapr_iommu_info;
+ ioctl(container, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &spapr_iommu_info);
+
+ if (ioctl(container, VFIO_IOMMU_ENABLE))
+ /* Cannot enable container, may be low rlimit */
+
+ /* Allocate some space and setup a DMA mapping */
+ dma_map.vaddr = mmap(0, 1024 * 1024, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+
+ dma_map.size = 1024 * 1024;
+ dma_map.iova = 0; /* 1MB starting at 0x0 from device view */
+ dma_map.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE;
+
+ /* Check here is .iova/.size are within DMA window from spapr_iommu_info */
+
+ ioctl(container, VFIO_IOMMU_MAP_DMA, &dma_map);
+ .....
+
-------------------------------------------------------------------------------
[1] VFIO was originally an acronym for "Virtual Function I/O" in its