Re: [Qemu-devel] [PATCH v5 05/11] vfio: Introduce VFIO address spaces

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 2014-03-28 at 14:42 +1100, Alexey Kardashevskiy wrote:
> On 03/20/2014 06:57 AM, Alex Williamson wrote:
> > On Wed, 2014-03-12 at 16:52 +1100, Alexey Kardashevskiy wrote:
> >> From: David Gibson <david@gibson.dropbear.id.au>
> >>
> >> 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 <david@gibson.dropbear.id.au>
> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> >>
> >> ---
> >> Changes:
> >> v5:
> >> * vfio_get_group() now receives AddressSpace*
> >>
> >> v4:
> >> * removed redundant checks and asserts
> >> * fixed some return error codes
> >> ---
> >>  hw/misc/vfio.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
> >>  1 file changed, 40 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> >> index 6a04c2a..c8236c3 100644
> >> --- a/hw/misc/vfio.c
> >> +++ b/hw/misc/vfio.c
> >> @@ -133,6 +133,22 @@ enum {
> >>      VFIO_INT_MSIX = 3,
> >>  };
> >>  
> >> +typedef struct VFIOAddressSpace {
> >> +    AddressSpace *as;
> >> +    QLIST_HEAD(, VFIOContainer) containers;
> >> +    QLIST_ENTRY(VFIOAddressSpace) list;
> >> +} VFIOAddressSpace;
> >> +
> >> +QLIST_HEAD(, VFIOAddressSpace) vfio_address_spaces;
> > 
> > Why isn't this static and initialized with QLIST_HEAD_INITIALIZER like
> > the qlist it replaces?
> 
> 
> I'll use QLIST_HEAD_INITIALIZER, ok.
> 
> 
> It is not static because otherwise it does not compile - the actual use of
> vfio_address_spaces happens in the next patches. Should I make it static
> and move to the next patch? Thanks.

So you're working around an unused variable compile failure by making it
non-static?  Why not just move declaring it until the next patch?
Thanks,

Alex

> >> +
> >> +static VFIOAddressSpace vfio_address_space_memory;
> >> +
> >> +static void vfio_address_space_init(VFIOAddressSpace *space, AddressSpace *as)
> >> +{
> >> +    space->as = as;
> >> +    QLIST_INIT(&space->containers);
> >> +}
> >> +
> >>  struct VFIOGroup;
> >>  
> >>  typedef struct VFIOType1 {
> >> @@ -142,6 +158,7 @@ typedef struct VFIOType1 {
> >>  } VFIOType1;
> >>  
> >>  typedef struct VFIOContainer {
> >> +    VFIOAddressSpace *space;
> >>      int fd; /* /dev/vfio/vfio, empowered by the attached groups */
> >>      struct {
> >>          /* enable abstraction to support various iommu backends */
> >> @@ -234,9 +251,6 @@ static const VFIORomBlacklistEntry romblacklist[] = {
> >>  
> >>  #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);
> >>  
> >> @@ -3280,16 +3294,15 @@ static void vfio_kvm_device_del_group(VFIOGroup *group)
> >>  #endif
> >>  }
> >>  
> >> -static int vfio_connect_container(VFIOGroup *group)
> >> +static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
> >>  {
> >>      VFIOContainer *container;
> >>      int ret, fd;
> >> +    VFIOAddressSpace *space;
> >>  
> >> -    if (group->container) {
> >> -        return 0;
> >> -    }
> >> +    space = &vfio_address_space_memory;
> >>  
> >> -    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);
> >> @@ -3312,6 +3325,7 @@ 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)) {
> >> @@ -3349,7 +3363,7 @@ 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);
> >> @@ -3392,7 +3406,7 @@ static void vfio_disconnect_container(VFIOGroup *group)
> >>      }
> >>  }
> >>  
> >> -static VFIOGroup *vfio_get_group(int groupid)
> >> +static VFIOGroup *vfio_get_group(int groupid, AddressSpace *as)
> >>  {
> >>      VFIOGroup *group;
> >>      char path[32];
> >> @@ -3400,7 +3414,14 @@ 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? */
> >> +            if (group->container->space->as == as) {
> >> +                return group;
> >> +            } else {
> >> +                error_report("vfio: group %d used in multiple address spaces",
> >> +                             group->groupid);
> >> +                return NULL;
> >> +            }
> >>          }
> >>      }
> >>  
> >> @@ -3428,7 +3449,7 @@ static VFIOGroup *vfio_get_group(int groupid)
> >>      group->groupid = groupid;
> >>      QLIST_INIT(&group->device_list);
> >>  
> >> -    if (vfio_connect_container(group)) {
> >> +    if (vfio_connect_container(group, as)) {
> >>          error_report("vfio: failed to setup container for group %d", groupid);
> >>          goto close_fd_exit;
> >>      }
> >> @@ -3780,7 +3801,12 @@ static int vfio_initfn(PCIDevice *pdev)
> >>      DPRINTF("%s(%04x:%02x:%02x.%x) group %d\n", __func__, vdev->host.domain,
> >>              vdev->host.bus, vdev->host.slot, vdev->host.function, groupid);
> >>  
> >> -    group = vfio_get_group(groupid);
> >> +    if (pci_device_iommu_address_space(pdev) != &address_space_memory) {
> >> +        error_report("vfio: DMA address space must be system memory");
> >> +        return -EINVAL;
> >> +    }
> >> +
> >> +    group = vfio_get_group(groupid, &address_space_memory);
> >>      if (!group) {
> >>          error_report("vfio: failed to get group %d", groupid);
> >>          return -ENOENT;
> >> @@ -3994,6 +4020,7 @@ static const TypeInfo vfio_pci_dev_info = {
> >>  
> >>  static void register_vfio_pci_dev_type(void)
> >>  {
> >> +    vfio_address_space_init(&vfio_address_space_memory, &address_space_memory);
> >>      type_register_static(&vfio_pci_dev_info);
> >>  }
> >>  
> > 
> > 
> > 
> 
>