Re: [PATCH v6 01/21] backends/iommufd: Introduce the iommufd object

[Cédric Le Goater]

Hello,

> +int iommufd_backend_map_dma(IOMMUFDBackend *be, uint32_t ioas_id, hwaddr iova,
> +                            ram_addr_t size, void *vaddr, bool readonly)
> +{
> +    int ret, fd = be->fd;
> +    struct iommu_ioas_map map = {
> +        .size = sizeof(map),
> +        .flags = IOMMU_IOAS_MAP_READABLE |
> +                 IOMMU_IOAS_MAP_FIXED_IOVA,
> +        .ioas_id = ioas_id,
> +        .__reserved = 0,
> +        .user_va = (uintptr_t)vaddr,
> +        .iova = iova,
> +        .length = size,
> +    };
> +
> +    if (!readonly) {
> +        map.flags |= IOMMU_IOAS_MAP_WRITEABLE;
> +    }
> +
> +    ret = ioctl(fd, IOMMU_IOAS_MAP, &map);
> +    trace_iommufd_backend_map_dma(fd, ioas_id, iova, size,
> +                                  vaddr, readonly, ret);
> +    if (ret) {
> +        ret = -errno;
> +        error_report("IOMMU_IOAS_MAP failed: %m");
> +    }
> +    return ret;
> +}

When using a UEFI guest, QEMU reports errors when mapping regions
in the top PCI space :

  iommufd_backend_map_dma  iommufd=10 ioas=2 iova=0x380000001000 size=0x3000 
addr=0x7fce2c28b000 readonly=0 (-1)
  qemu-system-x86_64: IOMMU_IOAS_MAP failed: Invalid argument
  qemu-system-x86_64: vfio_container_dma_map(0x55a21b03a150, 0x380000001000, 
0x3000, 0x7fce2c28b000) = -22 (Invalid argument)

  iommufd_backend_map_dma  iommufd=10 ioas=2 iova=0x380000004000 size=0x4000 
addr=0x7fce2c980000 readonly=0 (-1)
  qemu-system-x86_64: IOMMU_IOAS_MAP failed: Invalid argument
  qemu-system-x86_64: vfio_container_dma_map(0x55a21b03a150, 0x380000004000, 
0x4000, 0x7fce2c980000) = -22 (Invalid argument)

This is because IOMMUFD reserved IOVAs areas are :

 [ fee00000 - feefffff ]
 [ 8000000000 - ffffffffffffffff ] (39 bits address space)

which were allocated when the device was initially attached.
The topology is basic. Something is wrong.

Thanks,

C.