On Mon, 5 Mar 2018 12:37:24 +0100
Oliver Heid <oliver.h...@h-next.de> wrote:
> Do I miss something here? I want to allow RW access of a peripheral
> device to a memory region via
>
> struct vfio_iommu_type1_dma_map dma_map = { .argsz = sizeof(dma_map) };
>
> __u32* mem = (__u32*)mmap(NULL,size,PROT_READ|PROT_WRITE,
> MAP_SHARED|MAP_ANONYMOUS|MAP_LOCKED, -1, 0);
>
> dma_map.argsz = sizeof(dma_map);
> dma_map.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE;
> dma_map.vaddr = (__u64)mem;
> dma_map.iova = 0;
> dma_map.size = size;
>
> ioctl(container, VFIO_IOMMU_MAP_DMA, &dma_map);
>
> Any idea why theVFIO_IOMMU_MAP_DMA ioctl fails with EINVAL, but then a
> second, identical call succeeds? Does it actually succeed then? QEMU
> re-tries if the first attempt fails with EBUSY, but not with EINVAL.
I don't think the QEMU -EBUSY behavior is related, that handles
previous mappings and may no longer even be necessary. One of my unit
tests[1] does a similar map with no issues. Your code excerpt doesn't
check whether mmap succeeds, so for all we know mmap is failing too.
> The latest 4.15.7 kernel (4.15.6 too IIRC) does not recognize the AMD
> Ryzen 3 1200 as VFIO_TYPE1_IOMMU so I am using version 4.15.4.
This doesn't make sense, anything implementing the kernel's IOMMU API in
the kernel is compatible with type1, that includes anything supporting
AMD-Vi. There is no whitelist or specific processor support
selection. There are no iommu or vfio changes between the kernels
you're quoting, perhaps you could do a bisect. Thanks,
Alex
[1] https://github.com/awilliam/tests/blob/master/vfio-iommu-map-unmap.c
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