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.
>
> Paolo
hi Paolo
Thanks and I'll try it tomorrow and let you know the result.
But may I know why it cannot simply be like below?
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;
