Tested-by: Yan Zhao <yan.y.z...@intel.com>
On Mon, Jun 24, 2019 at 05:18:11PM +0800, Peter Xu wrote:
> 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: Peter Xu <pet...@redhat.com>
> ---
> hw/i386/intel_iommu.c | 67 ++++++++++++++++++++++++++-----------------
> 1 file changed, 41 insertions(+), 26 deletions(-)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 719ce19ab3..de86f53b4e 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3363,11 +3363,28 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s,
> PCIBus *bus, int devfn)
> return vtd_dev_as;
> }
>
> +static uint64_t get_naturally_aligned_size(uint64_t start,
> + uint64_t size, int gaw)
> +{
> + uint64_t max_mask = 1ULL << gaw;
> + uint64_t alignment = start ? start & -start : max_mask;
> +
> + alignment = MIN(alignment, max_mask);
> + size = MIN(size, max_mask);
> +
> + if (alignment <= size) {
> + /* Increase the alignment of start */
> + return alignment;
> + } else {
> + /* 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 +3405,37 @@ 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 >= VTD_PAGE_SIZE) {
> + IOMMUTLBEntry entry;
> + uint64_t mask = get_naturally_aligned_size(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
>
