On 20/06/19 12:57, Yan Zhao wrote: > On Thu, Jun 20, 2019 at 04:35:29PM +0800, Paolo Bonzini wrote: >> On 20/06/19 06:02, Peter Xu wrote: >>> Seems workable, to be explicit - we can even cut it into chunks with >>> different size to be efficient. >> >> Yes, this is not hard (completely untested): >> >> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c >> index 44b1231157..541538bc6c 100644 >> --- a/hw/i386/intel_iommu.c >> +++ b/hw/i386/intel_iommu.c >> @@ -3388,39 +3388,34 @@ static void vtd_address_space_unmap(VTDAddressSpace >> *as, IOMMUNotifier *n) >> } >> >> assert(start <= end); >> - size = end - start; >> + while (end > start) { >> + size = end - start; >> + /* Only keep the lowest bit of either size or start. */ >> + size = MIN(size & -size, start & -start); >> + /* Should not happen, but limit to address width too just in case */ >> + size = MIN(size, 1ULL << s->aw_bits); >> >> - 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; >> - } >> + assert((start & (size - 1)) == 0); >> >> - 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; >> + entry.target_as = &address_space_memory; >> + entry.iova = start; >> + /* This field is meaningless for unmap */ >> + entry.translated_addr = 0; >> + entry.perm = IOMMU_NONE; >> + entry.addr_mask = size - 1; >> >> - trace_vtd_as_unmap_whole(pci_bus_num(as->bus), >> - VTD_PCI_SLOT(as->devfn), >> - VTD_PCI_FUNC(as->devfn), >> - entry.iova, size); >> + trace_vtd_as_unmap_whole(pci_bus_num(as->bus), >> + VTD_PCI_SLOT(as->devfn), >> + VTD_PCI_FUNC(as->devfn), >> + entry.iova, size); >> >> - map.iova = entry.iova; >> - map.size = entry.addr_mask; >> - iova_tree_remove(as->iova_tree, &map); >> + map.iova = entry.iova; >> + map.size = entry.addr_mask; >> + iova_tree_remove(as->iova_tree, &map); >> >> - memory_region_notify_one(n, &entry); >> + memory_region_notify_one(n, &entry); >> + start += size; >> + } >> } >> >> static void vtd_address_space_unmap_all(IntelIOMMUState *s) >> >> >> Yan, >> >> if something like this works for you, let me know and I will submit it >> as a proper patch. > > Thanks and I'll try it tomorrow and let you know the result. > But may I know why it cannot simply be like below?
Because the API is that addr_mask is a power of two minus 1. Paolo > Thanks > Yan > > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > index b0d8a1c..2956db6 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -3374,7 +3374,6 @@ static void vtd_address_space_unmap(VTDAddressSpace > *as, IOMMUNotifier *n) > IntelIOMMUState *s = as->iommu_state; > DMAMap map; > > /* > * Note: all the codes in this function has a assumption that IOVA > * bits are no more than VTD_MGAW bits (which is restricted by > @@ -3392,23 +3391,8 @@ static void vtd_address_space_unmap(VTDAddressSpace > *as, IOMMUNotifier *n) > assert(start <= end); > size = end - start; > > - 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; > - } > - > - > entry.target_as = &address_space_memory; > - /* Adjust iova for the size */ > - entry.iova = n->start & ~(size - 1); > + entry.iova = n->start; > /* This field is meaningless for unmap */ > entry.translated_addr = 0; > entry.perm = IOMMU_NONE; > > >