Hi Matthew, On 9/15/20 12:29 AM, Matthew Rosato wrote: > The underlying host may be limiting the number of outstanding DMA > requests for type 1 IOMMU. Add helper functions to check for the > DMA available capability and retrieve the current number of DMA > mappings allowed. > > Signed-off-by: Matthew Rosato <mjros...@linux.ibm.com> > --- > hw/vfio/common.c | 37 +++++++++++++++++++++++++++++++++++++ > include/hw/vfio/vfio-common.h | 2 ++ > 2 files changed, 39 insertions(+) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 3335714..7f4a338 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -844,6 +844,43 @@ vfio_get_region_info_cap(struct vfio_region_info *info, > uint16_t id) > return NULL; > } > > +static struct vfio_info_cap_header * > +vfio_get_iommu_type1_info_cap(struct vfio_iommu_type1_info *info, uint16_t > id) > +{ > + struct vfio_info_cap_header *hdr; > + void *ptr = info; > + > + if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) { > + return NULL; > + } > + > + for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) { > + if (hdr->id == id) { > + return hdr; > + } > + } > + > + return NULL; > +} > + > +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info, > + unsigned int *avail) > +{ > + struct vfio_info_cap_header *hdr; > + struct vfio_iommu_type1_info_dma_avail *cap; > + > + /* If the capability cannot be found, assume no DMA limiting */ > + hdr = vfio_get_iommu_type1_info_cap(info, > + VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL); > + if (hdr == NULL || avail == NULL) {
If you expect the caller to use avail=NULL, then why return false when there is available information? > + return false; > + } > + > + cap = (void *) hdr; > + *avail = cap->avail; > + return true; > +} > + > static int vfio_setup_region_sparse_mmaps(VFIORegion *region, > struct vfio_region_info *info) > { > diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h > index c78f3ff..661a380 100644 > --- a/include/hw/vfio/vfio-common.h > +++ b/include/hw/vfio/vfio-common.h > @@ -178,6 +178,8 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, > Error **errp); > void vfio_put_group(VFIOGroup *group); > int vfio_get_device(VFIOGroup *group, const char *name, > VFIODevice *vbasedev, Error **errp); > +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info, > + unsigned int *avail); > > extern const MemoryRegionOps vfio_region_ops; > typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList; >