Hi Yan, [+ Peter]
On 6/19/19 10:49 AM, Yan Zhao wrote: > even if an entry overlaps with notifier's range, should not map/unmap > out of bound part in the entry. I don't think the patch was based on the master as the trace at the very end if not part of the upstream code. > > This would cause problem in below case: > 1. initially there are two notifiers with ranges > 0-0xfedfffff, 0xfef00000-0xffffffffffffffff, > IOVAs from 0x3c000000 - 0x3c1fffff is in shadow page table. > > 2. in vfio, memory_region_register_iommu_notifier() is followed by > memory_region_iommu_replay(), which will first call address space unmap, > and walk and add back all entries in vtd shadow page table. e.g. > (1) for notifier 0-0xfedfffff, > IOVAs from 0 - 0xffffffff get unmapped, > and IOVAs from 0x3c000000 - 0x3c1fffff get mapped While the patch looks sensible, the issue is the notifier scope used in vtd_address_space_unmap is not a valid mask (ctpop64(size) != 1). Then the size is recomputed (either using n = 64 - clz64(size) for the 1st notifier or n = s->aw_bits for the 2d) and also the entry (especially for the 2d notifier where it becomes 0) to get a proper alignment. vtd_page_walk sends notifications per block or page (with valid addr_mask) so stays within the notifier. Modifying the entry->iova/addr_mask again in memory_region_notify_one leads to unaligned start address / addr_mask. I don't think we want that. Can't we modity the vtd_address_space_unmap() implementation to split the invalidation in smaller chunks instead? Thanks Eric > (2) for notifier 0xfef00000-0xffffffffffffffff > IOVAs from 0 - 0x7fffffffff get unmapped,> but IOVAs from 0x3c000000 > - 0x3c1fffff cannot get mapped back. > > Signed-off-by: Yan Zhao <yan.y.z...@intel.com> > --- > memory.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/memory.c b/memory.c > index 07c8315..a6b9da6 100644 > --- a/memory.c > +++ b/memory.c > @@ -1948,6 +1948,14 @@ void memory_region_notify_one(IOMMUNotifier *notifier, > return; > } > > + if (entry->iova < notifier->start) { > + entry->iova = notifier->start; > + } > + > + if (entry->iova + entry->addr_mask > notifier->end) { > + entry->addr_mask = notifier->end - entry->iova;> + } > + > if (entry->perm & IOMMU_RW) { > printf("map %lx %lx\n", entry->iova, entry->iova + entry->addr_mask); > request_flags = IOMMU_NOTIFIER_MAP; >