> From: Shameerali Kolothum Thodi > [mailto:shameerali.kolothum.thodi@xxxxxxxxxx] > > > -----Original Message----- > > From: Tian, Kevin [mailto:kevin.tian@xxxxxxxxx] > > Sent: Monday, March 19, 2018 7:52 AM > > To: Shameerali Kolothum Thodi > <shameerali.kolothum.thodi@xxxxxxxxxx>; > > alex.williamson@xxxxxxxxxx; eric.auger@xxxxxxxxxx; > > pmorel@xxxxxxxxxxxxxxxxxx > > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; xuwei (O) > > <xuwei5@xxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx>; > > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx > > Subject: RE: [PATCH v5 2/7] vfio/type1: Check reserve region conflict and > > update iova list > > > > > From: Shameer Kolothum > > > Sent: Friday, March 16, 2018 12:35 AM > > > > > > This retrieves the reserved regions associated with dev group and > > > checks for conflicts with any existing dma mappings. Also update > > > the iova list excluding the reserved regions. > > > > > > Signed-off-by: Shameer Kolothum > > > <shameerali.kolothum.thodi@xxxxxxxxxx> > > > --- > > > drivers/vfio/vfio_iommu_type1.c | 90 > > > +++++++++++++++++++++++++++++++++++++++++ > > > 1 file changed, 90 insertions(+) > > > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c > > > b/drivers/vfio/vfio_iommu_type1.c > > > index 1123c74..cfe2bb2 100644 > > > --- a/drivers/vfio/vfio_iommu_type1.c > > > +++ b/drivers/vfio/vfio_iommu_type1.c > > > @@ -1313,6 +1313,82 @@ static int vfio_iommu_aper_resize(struct > > > list_head *iova, > > > return 0; > > > } > > > > > > +/* > > > + * Check reserved region conflicts with existing dma mappings > > > + */ > > > +static bool vfio_iommu_resv_conflict(struct vfio_iommu *iommu, > > > + struct list_head *resv_regions) > > > +{ > > > + struct iommu_resv_region *region; > > > + > > > + /* Check for conflict with existing dma mappings */ > > > + list_for_each_entry(region, resv_regions, list) { > > > + if (vfio_find_dma(iommu, region->start, region->length)) > > > + return true; > > > + } > > > + > > > + return false; > > > +} > > > + > > > +/* > > > + * Check iova region overlap with reserved regions and > > > + * exclude them from the iommu iova range > > > + */ > > > +static int vfio_iommu_resv_exclude(struct list_head *iova, > > > + struct list_head *resv_regions) > > > +{ > > > + struct iommu_resv_region *resv; > > > + struct vfio_iova *n, *next; > > > + > > > + list_for_each_entry(resv, resv_regions, list) { > > > + phys_addr_t start, end; > > > + > > > + start = resv->start; > > > + end = resv->start + resv->length - 1; > > > + > > > + list_for_each_entry_safe(n, next, iova, list) { > > > + int ret = 0; > > > + > > > + /* No overlap */ > > > + if ((start > n->end) || (end < n->start)) > > > + continue; > > > + /* > > > + * Insert a new node if current node overlaps with > > > the > > > + * reserve region to exlude that from valid iova > > > range. > > > + * Note that, new node is inserted before the > > > current > > > + * node and finally the current node is deleted > > > keeping > > > + * the list updated and sorted. > > > + */ > > > + if (start > n->start) > > > + ret = vfio_iommu_iova_insert(&n->list, > > > + n->start, start - 1); > > > + if (!ret && end < n->end) > > > + ret = vfio_iommu_iova_insert(&n->list, > > > + end + 1, n->end); > > > + if (ret) > > > + return ret; > > > > Is it safer to delete the 1st node here in case of failure of the 2nd node? > > There is no problem with current logic since upon error iova_copy will > > be released anyway. However this function alone doesn't assume the > > fact of a temporary list, thus it's better to keep the list clean w/o garbage > > left from any error handling. > > Agree. I will consider this. > > > > + > > > + list_del(&n->list); > > > + kfree(n); > > > + } > > > + } > > > + > > > + if (list_empty(iova)) > > > + return -EINVAL; > > > > if list_empty should BUG_ON here? or do we really need this check? > > I think we need the check here. This basically means there is no valid iova > region as the reserved regions overlaps it completely(very unlikely, a bad > configuration maybe). The __attach will fail if that happens and may be > WARN_ON is a good idea to notify the user. > you are right. I misread the code that deletion happens only after insertion... Thanks Kevin
