Tested-by: Yan Zhao <yan.y.z...@intel.com>
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) {
> + 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;
> }
>
> - 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
>
