On Mon, Jun 24, 2019 at 02:37:33PM +0800, Peter Xu wrote: > From: Paolo Bonzini <pbonz...@redhat.com> > > This is an replacement work of Yan Zhao's patch: > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg625340.html > > vtd_address_space_unmap() will do proper page mask alignment to make > sure each IOTLB message will have correct masks for notification > messages (2^N-1), but sometimes it can be expanded to even supercede > the registered range. That could lead to unexpected UNMAP of already > mapped regions in some other notifiers. > > Instead of doing mindless expension of the start address and address > mask, we split the range into smaller ones and guarantee that each > small range will have correct masks (2^N-1) and at the same time we > should also try our best to generate as less IOTLB messages as > possible. > > Reported-by: Yan Zhao <yan.y.z...@intel.com> > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > [peterx: fixup mask generation algos and other touchups, introduce > vtd_get_next_mask(), write commit message] > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > hw/i386/intel_iommu.c | 70 +++++++++++++++++++++++++++---------------- > 1 file changed, 44 insertions(+), 26 deletions(-) > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index 719ce19ab3..39cedf73b8 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -3363,11 +3363,31 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, > PCIBus *bus, int devfn) > return vtd_dev_as; > } > > +static uint64_t vtd_get_next_mask(uint64_t start, uint64_t size, int gaw) > +{ > + /* Tries to find smallest mask from start first */ > + uint64_t rmask = start & -start, max_mask = 1ULL << gaw; > + > + assert(size && gaw > 0 && gaw < 64); > + > + /* Zero start, or too big */ > + if (!rmask || rmask > max_mask) { > + rmask = max_mask; > + } > + > + /* If the start mask worked, then use it */ > + if (rmask <= size) { > + return rmask; > + } > + > + /* Find the largest page mask from size */ > + return 1ULL << (63 - clz64(size)); > +} > + > /* Unmap the whole range in the notifier's scope. */ > static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n) > { > - IOMMUTLBEntry entry; > - hwaddr size; > + hwaddr size, remain; > hwaddr start = n->start; > hwaddr end = n->end; > IntelIOMMUState *s = as->iommu_state; > @@ -3388,39 +3408,37 @@ static void vtd_address_space_unmap(VTDAddressSpace > *as, IOMMUNotifier *n) > } > > assert(start <= end); > - size = end - start; > + size = remain = end - start + 1; > > - if (ctpop64(size) != 1) { > - /* > - * This size cannot format a correct mask. Let's enlarge it to > - * suite the minimum available mask. > - */ > - int n = 64 - clz64(size); > - if (n > s->aw_bits) { > - /* should not happen, but in case it happens, limit it */ > - n = s->aw_bits; > - } > - size = 1ULL << n; > + while (remain > 0) { hi I think here remain should still be "remain >= VTD_PAGE_SIZE" because we cannot unmap entry less than PAGE_SIZE.
> + IOMMUTLBEntry entry; > + uint64_t mask = vtd_get_next_mask(start, remain, s->aw_bits); > + > + assert(mask); > + > + entry.iova = start; > + entry.addr_mask = mask - 1; > + entry.target_as = &address_space_memory; > + entry.perm = IOMMU_NONE; > + /* This field is meaningless for unmap */ > + entry.translated_addr = 0; > + > + memory_region_notify_one(n, &entry); > + > + start += mask; > + remain -= mask; > } Add assert(remain) here? > > - entry.target_as = &address_space_memory; > - /* Adjust iova for the size */ > - entry.iova = n->start & ~(size - 1); > - /* This field is meaningless for unmap */ > - entry.translated_addr = 0; > - entry.perm = IOMMU_NONE; > - entry.addr_mask = size - 1; > + assert(!remain); > > trace_vtd_as_unmap_whole(pci_bus_num(as->bus), > VTD_PCI_SLOT(as->devfn), > VTD_PCI_FUNC(as->devfn), > - entry.iova, size); > + n->start, size); > > - map.iova = entry.iova; > - map.size = entry.addr_mask; > + map.iova = n->start; > + map.size = size; > iova_tree_remove(as->iova_tree, &map); > - > - memory_region_notify_one(n, &entry); > } > > static void vtd_address_space_unmap_all(IntelIOMMUState *s) > -- > 2.21.0 >
