On Thu, Jun 20, 2019 at 10:35:29AM +0200, 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);
I feel like this can be problematic. I'm imaging:
start=0x1000_0000, size=0x1000_1000
This will get size=0x1000 but actually we can do size=0x1000_0000 as
the first.
> + /* 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;
(some of the fields can be moved out of loop because they are
constants)
>
> - 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);
Can move this out because this is a trace only so we don't have
restriction on mask?
>
> - 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);
Same here?
>
> - 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
Since during review I'm thinking how to generate a correct sequence of
these masks... here's my try below with above issues fixed... :)
I've tried compile but not tested. Yan can test it, or I can do it
too tomorrow after I find some machines.
Thanks,
------------------------------------------------------------
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 44b1231157..cfbd225f0a 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3363,11 +3363,32 @@ 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 +3409,28 @@ 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;
- }
-
+ size = remain = end - start;
entry.target_as = &address_space_memory;
- /* Adjust iova for the size */
- entry.iova = n->start & ~(size - 1);
+ entry.perm = IOMMU_NONE;
/* This field is meaningless for unmap */
entry.translated_addr = 0;
- entry.perm = IOMMU_NONE;
- entry.addr_mask = size - 1;
+
+ while (remain) {
+ uint64_t mask = vtd_get_next_mask(start, remain, s->aw_bits);
+
+ entry.iova = start;
+ entry.addr_mask = mask - 1;
+ memory_region_notify_one(n, &entry);
+ }
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)
------------------------------------------------------------
Regards,
--
Peter Xu
