Re: [PATCH v2 18/23] vfio-user: add dma_unmap_all

[Alex Williamson]

On Wed,  1 Feb 2023 21:55:54 -0800
John Johnson <john.g.johnson@oracle.com> wrote:

> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> ---
>  include/hw/vfio/vfio-common.h |  1 +
>  hw/vfio/common.c              | 45 
> ++++++++++++++++++++++++++++++++++---------
>  hw/vfio/user.c                | 24 +++++++++++++++++++++++
>  3 files changed, 61 insertions(+), 9 deletions(-)

This is inventing a need for a kernel vs user callback op rather than
probing support for VFIO_UNMAP_ALL and using VFIO_DMA_UNMAP_FLAG_VADDR
consistently.  The flags arg of the dma_unmap_all() op is unused and
the kernel implementation introduces hard coded magic values.  The
vfio-user dirty_bitmap addition here is rather random.  Please include
some sort of description in the commit log for all patches.  Thanks,

Alex

> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index ee6ad8f..abef9b4 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -193,6 +193,7 @@ struct VFIOContainerIO {
>      int (*dma_unmap)(VFIOContainer *container,
>                       struct vfio_iommu_type1_dma_unmap *unmap,
>                       struct vfio_bitmap *bitmap);
> +    int (*dma_unmap_all)(VFIOContainer *container, uint32_t flags);
>      int (*dirty_bitmap)(VFIOContainer *container,
>                          struct vfio_iommu_type1_dirty_bitmap *bitmap,
>                          struct vfio_iommu_type1_dirty_bitmap_get *range);
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index f04fd20..8b55fbb 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -508,6 +508,14 @@ static int vfio_dma_unmap(VFIOContainer *container,
>      return container->io->dma_unmap(container, &unmap, NULL);
>  }
>  
> +/*
> + * DMA - Mapping and unmapping for the "type1" IOMMU interface used on x86
> + */
> +static int vfio_dma_unmap_all(VFIOContainer *container)
> +{
> +    return container->io->dma_unmap_all(container, VFIO_DMA_UNMAP_FLAG_ALL);
> +}
> +
>  static int vfio_dma_map(VFIOContainer *container, MemoryRegion *mr, hwaddr 
> iova,
>                          ram_addr_t size, void *vaddr, bool readonly)
>  {
> @@ -1256,17 +1264,10 @@ static void vfio_listener_region_del(MemoryListener 
> *listener,
>  
>      if (try_unmap) {
>          if (int128_eq(llsize, int128_2_64())) {
> -            /* The unmap ioctl doesn't accept a full 64-bit span. */
> -            llsize = int128_rshift(llsize, 1);
> +            ret = vfio_dma_unmap_all(container);
> +        } else {
>              ret = vfio_dma_unmap(container, iova, int128_get64(llsize), 
> NULL);
> -            if (ret) {
> -                error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
> -                             "0x%"HWADDR_PRIx") = %d (%m)",
> -                             container, iova, int128_get64(llsize), ret);
> -            }
> -            iova += int128_get64(llsize);
>          }
> -        ret = vfio_dma_unmap(container, iova, int128_get64(llsize), NULL);
>          if (ret) {
>              error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
>                           "0x%"HWADDR_PRIx") = %d (%m)",
> @@ -2867,6 +2868,31 @@ static int vfio_io_dma_unmap(VFIOContainer *container,
>      return 0;
>  }
>  
> +static int vfio_io_dma_unmap_all(VFIOContainer *container, uint32_t flags)
> +{
> +    struct vfio_iommu_type1_dma_unmap unmap = {
> +        .argsz = sizeof(unmap),
> +        .flags = 0,
> +        .size = 0x8000000000000000,
> +    };
> +    int ret;
> +
> +    /* The unmap ioctl doesn't accept a full 64-bit span. */
> +    unmap.iova = 0;
> +    ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap);
> +    if (ret) {
> +        return -errno;
> +    }
> +
> +    unmap.iova += unmap.size;
> +    ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap);
> +    if (ret) {
> +        return -errno;
> +    }
> +
> +    return 0;
> +}
> +
>  static int vfio_io_dirty_bitmap(VFIOContainer *container,
>                                  struct vfio_iommu_type1_dirty_bitmap *bitmap,
>                                  struct vfio_iommu_type1_dirty_bitmap_get 
> *range)
> @@ -2886,6 +2912,7 @@ static void vfio_io_wait_commit(VFIOContainer 
> *container)
>  static VFIOContainerIO vfio_cont_io_ioctl = {
>      .dma_map = vfio_io_dma_map,
>      .dma_unmap = vfio_io_dma_unmap,
> +    .dma_unmap_all = vfio_io_dma_unmap_all,
>      .dirty_bitmap = vfio_io_dirty_bitmap,
>      .wait_commit = vfio_io_wait_commit,
>  };
> diff --git a/hw/vfio/user.c b/hw/vfio/user.c
> index 6dee775..fe6e476 100644
> --- a/hw/vfio/user.c
> +++ b/hw/vfio/user.c
> @@ -1825,6 +1825,28 @@ static int vfio_user_io_dma_unmap(VFIOContainer 
> *container,
>                                 container->async_ops);
>  }
>  
> +static int vfio_user_io_dma_unmap_all(VFIOContainer *container, uint32_t 
> flags)
> +{
> +    struct vfio_iommu_type1_dma_unmap unmap = {
> +        .argsz = sizeof(unmap),
> +        .flags = flags | VFIO_DMA_UNMAP_FLAG_ALL,
> +        .iova = 0,
> +        .size = 0,
> +    };
> +
> +    return vfio_user_dma_unmap(container->proxy, &unmap, NULL,
> +                               container->async_ops);
> +}
> +
> +static int vfio_user_io_dirty_bitmap(VFIOContainer *container,
> +                        struct vfio_iommu_type1_dirty_bitmap *bitmap,
> +                        struct vfio_iommu_type1_dirty_bitmap_get *range)
> +{
> +
> +    /* vfio-user doesn't support migration */
> +    return -EINVAL;
> +}
> +
>  static void vfio_user_io_wait_commit(VFIOContainer *container)
>  {
>      vfio_user_wait_reqs(container->proxy);
> @@ -1833,5 +1855,7 @@ static void vfio_user_io_wait_commit(VFIOContainer 
> *container)
>  VFIOContainerIO vfio_cont_io_sock = {
>      .dma_map = vfio_user_io_dma_map,
>      .dma_unmap = vfio_user_io_dma_unmap,
> +    .dma_unmap_all = vfio_user_io_dma_unmap_all,
> +    .dirty_bitmap = vfio_user_io_dirty_bitmap,
>      .wait_commit = vfio_user_io_wait_commit,
>  };