Re: [Qemu-devel] [Qemu-ppc] [PATCH 07/11] vfio: Introduce VFIO address spaces

[David Gibson]

On Tue, May 14, 2013 at 10:53:12AM -0600, Alex Williamson wrote:
> On Tue, 2013-05-14 at 19:13 +1000, David Gibson wrote:
> > The only model so far supported for VFIO passthrough devices is the model
> > usually used on x86, where all of the guest's RAM is mapped into the
> > (host) IOMMU and there is no IOMMU visible in the guest.
> > 
> > This patch begins to relax this model, introducing the notion of a
> > VFIOAddressSpace.  This represents a logical DMA address space which will
> > be visible to one or more VFIO devices by appropriate mapping in the (host)
> > IOMMU.  Thus the currently global list of containers becomes local to
> > a VFIOAddressSpace, and we verify that we don't attempt to add a VFIO
> > group to multiple address spaces.
> > 
> > For now, only one VFIOAddressSpace is created and used, corresponding to
> > main system memory, that will change in future patches.
> > 
> > Signed-off-by: David Gibson <address@hidden>
> > ---
> >  hw/misc/vfio.c |   63 
> > ++++++++++++++++++++++++++++++++++++++++++--------------
> >  1 file changed, 48 insertions(+), 15 deletions(-)
> > 
> > diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> > index c4a8853..e557f69 100644
> > --- a/hw/misc/vfio.c
> > +++ b/hw/misc/vfio.c
> > @@ -113,9 +113,17 @@ enum {
> >      VFIO_INT_MSIX = 3,
> >  };
> >  
> > +typedef struct VFIOAddressSpace {
> > +    AddressSpace *as;
> > +    QLIST_HEAD(, VFIOContainer) containers;
> > +} VFIOAddressSpace;
> > +
> > +static VFIOAddressSpace vfio_address_space_memory;
> > +
> >  struct VFIOGroup;
> >  
> >  typedef struct VFIOContainer {
> > +    VFIOAddressSpace *space;
> >      int fd; /* /dev/vfio/vfio, empowered by the attached groups */
> >      struct {
> >          /* enable abstraction to support various iommu backends */
> > @@ -178,9 +186,6 @@ typedef struct VFIOGroup {
> >  
> >  #define MSIX_CAP_LENGTH 12
> >  
> > -static QLIST_HEAD(, VFIOContainer)
> > -    container_list = QLIST_HEAD_INITIALIZER(container_list);
> > -
> >  static QLIST_HEAD(, VFIOGroup)
> >      group_list = QLIST_HEAD_INITIALIZER(group_list);
> >  
> > @@ -2624,16 +2629,28 @@ static int vfio_load_rom(VFIODevice *vdev)
> >      return 0;
> >  }
> >  
> > -static int vfio_connect_container(VFIOGroup *group)
> > +static void vfio_address_space_init(VFIOAddressSpace *space, AddressSpace 
> > *as)
> > +{
> > +    space->as = as;
> > +    QLIST_INIT(&space->containers);
> > +}
> > +
> > +static int vfio_connect_container(VFIOGroup *group, VFIOAddressSpace 
> > *space)
> >  {
> >      VFIOContainer *container;
> >      int ret, fd;
> >  
> >      if (group->container) {
> > -        return 0;
> > +        if (group->container->space == space) {
> > +            return 0;
> > +        } else {
> > +            error_report("vfio: group %d used in multiple address spaces",
> > +                         group->groupid);
> > +            return -EBUSY;
> > +        }
> >      }
> >  
> > -    QLIST_FOREACH(container, &container_list, next) {
> > +    QLIST_FOREACH(container, &space->containers, next) {
> >          if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) {
> >              group->container = container;
> >              QLIST_INSERT_HEAD(&container->group_list, group, 
> > container_next);
> > @@ -2656,6 +2673,7 @@ static int vfio_connect_container(VFIOGroup *group)
> >      }
> >  
> >      container = g_malloc0(sizeof(*container));
> > +    container->space = space;
> >      container->fd = fd;
> >  
> >      if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU)) {
> > @@ -2678,7 +2696,8 @@ static int vfio_connect_container(VFIOGroup *group)
> >          container->iommu_data.listener = vfio_memory_listener;
> >          container->iommu_data.release = vfio_listener_release;
> >  
> > -        memory_listener_register(&container->iommu_data.listener, 
> > &address_space_memory);
> > +        memory_listener_register(&container->iommu_data.listener,
> > +                                 container->space->as);
> >      } else {
> >          error_report("vfio: No available IOMMU models");
> >          g_free(container);
> > @@ -2687,7 +2706,7 @@ static int vfio_connect_container(VFIOGroup *group)
> >      }
> >  
> >      QLIST_INIT(&container->group_list);
> > -    QLIST_INSERT_HEAD(&container_list, container, next);
> > +    QLIST_INSERT_HEAD(&space->containers, container, next);
> >  
> >      group->container = container;
> >      QLIST_INSERT_HEAD(&container->group_list, group, container_next);
> > @@ -2700,7 +2719,7 @@ static void vfio_disconnect_container(VFIOGroup 
> > *group)
> >      VFIOContainer *container = group->container;
> >  
> >      if (ioctl(group->fd, VFIO_GROUP_UNSET_CONTAINER, &container->fd)) {
> > -        error_report("vfio: error disconnecting group %d from container",
> > +        error_report("vfio: error disconnecting group %d from context",
> >                       group->groupid);
> >      }
> >  
> > @@ -2712,13 +2731,13 @@ static void vfio_disconnect_container(VFIOGroup 
> > *group)
> >              container->iommu_data.release(container);
> >          }
> >          QLIST_REMOVE(container, next);
> > -        DPRINTF("vfio_disconnect_container: close container->fd\n");
> > +        DPRINTF("vfio_disconnect: close container->fd\n");
> >          close(container->fd);
> >          g_free(container);
> >      }
> >  }
> 
> Drop the above two chunks.
>  
> > -static VFIOGroup *vfio_get_group(int groupid)
> > +static VFIOGroup *vfio_get_group(int groupid, VFIOAddressSpace *space)
> >  {
> >      VFIOGroup *group;
> >      char path[32];
> > @@ -2726,7 +2745,15 @@ static VFIOGroup *vfio_get_group(int groupid)
> >  
> >      QLIST_FOREACH(group, &group_list, next) {
> >          if (group->groupid == groupid) {
> > -            return group;
> > +            /* Found it.  Now is it already in the right context? */
> > +            assert(group->container);
> > +            if (group->container->space == space) {
> > +                return group;
> > +            } else {
> > +                error_report("vfio: group %d used in multiple address 
> > spaces",
> > +                             group->groupid);
> > +                return NULL;
> > +            }
> >          }
> >      }
> >  
> > @@ -2759,8 +2786,8 @@ static VFIOGroup *vfio_get_group(int groupid)
> >      group->groupid = groupid;
> >      QLIST_INIT(&group->device_list);
> >  
> > -    if (vfio_connect_container(group)) {
> > -        error_report("vfio: failed to setup container for group %d", 
> > groupid);
> > +    if (vfio_connect_container(group, space)) {
> > +        error_report("vfio: failed to setup context for group %d", 
> > groupid);
> 
> s/container/context/ is unnecessary now.

Ah, yes, fixed.

-- 
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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