Re: [Qemu-devel] [PATCH qemu v5 04/12] spapr_pci_vfio: Enable multiple groups per container

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Mar 31, 2015 at 04:28:39PM +1100, Alexey Kardashevskiy wrote:
> This enables multiple IOMMU groups in one VFIO container which means
> that multiple devices from different groups can share the same IOMMU
> table (or tables if DDW).
> 
> This removes a group id from vfio_container_ioctl(). The kernel support
> is required for this; if the host kernel does not have the support,
> it will allow only one group per container. The PHB's "iommuid" property
> is ignored.
> 
> This adds a sanity check that there is just one VFIO container per
> PHB address space.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

[snip]
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index b012620..99e1900 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -915,21 +915,23 @@ void vfio_put_base_device(VFIODevice *vbasedev)
>      close(vbasedev->fd);
>  }
>  
> -static int vfio_container_do_ioctl(AddressSpace *as, int32_t groupid,
> +static int vfio_container_do_ioctl(AddressSpace *as,
>                                     int req, void *param)
>  {
> -    VFIOGroup *group;
>      VFIOContainer *container;
> -    int ret = -1;
> +    int ret;
> +    VFIOAddressSpace *space;
>  
> -    group = vfio_get_group(groupid, as);
> -    if (!group) {
> -        error_report("vfio: group %d not registered", groupid);
> -        return ret;
> -    }
> +    space = vfio_get_address_space(as);
> +    container = QLIST_FIRST(&space->containers);

So getting the container handle from the address space, rather than
the group id certainly makes more sense to me.

> -    container = group->container;
> -    if (group->container) {
> +    if (!container) {
> +        error_report("vfio: container is not set");
> +        return -1;
> +    } else if (QLIST_NEXT(container, next)) {
> +        error_report("vfio: multiple containers per PHB are not supported");
> +        return -1;

But if only one PHB per address space is possible, why is the
containers field a list in the first place?

> +    } else {
>          ret = ioctl(container->fd, req, param);
>          if (ret < 0) {
>              error_report("vfio: failed to ioctl %d to container: ret=%d, %s",
> @@ -937,12 +939,10 @@ static int vfio_container_do_ioctl(AddressSpace *as, int32_t groupid,
>          }
>      }
>  
> -    vfio_put_group(group);
> -
>      return ret;
>  }
>  
> -int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
> +int vfio_container_ioctl(AddressSpace *as,
>                           int req, void *param)
>  {
>      /* We allow only certain ioctls to the container */
> @@ -957,5 +957,5 @@ int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>          return -1;
>      }
>  
> -    return vfio_container_do_ioctl(as, groupid, req, param);
> +    return vfio_container_do_ioctl(as, req, param);
>  }
> diff --git a/include/hw/vfio/vfio.h b/include/hw/vfio/vfio.h
> index 0b26cd8..76b5744 100644
> --- a/include/hw/vfio/vfio.h
> +++ b/include/hw/vfio/vfio.h
> @@ -3,7 +3,7 @@
>  
>  #include "qemu/typedefs.h"
>  
> -extern int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
> +extern int vfio_container_ioctl(AddressSpace *as,
>                                  int req, void *param);
>  
>  #endif

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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