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Re: [PATCH v26 13/17] vfio: create mapped iova list when vIOMMU is enabl
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From: |
Alex Williamson |
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Subject: |
Re: [PATCH v26 13/17] vfio: create mapped iova list when vIOMMU is enabled |
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Date: |
Mon, 19 Oct 2020 11:24:08 -0600 |
On Mon, 19 Oct 2020 11:31:03 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:
> On 9/26/2020 3:53 AM, Alex Williamson wrote:
> > On Wed, 23 Sep 2020 04:54:15 +0530
> > Kirti Wankhede <kwankhede@nvidia.com> wrote:
> >
> >> Create mapped iova list when vIOMMU is enabled. For each mapped iova
> >> save translated address. Add node to list on MAP and remove node from
> >> list on UNMAP.
> >> This list is used to track dirty pages during migration.
> >>
> >> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> >> ---
> >> hw/vfio/common.c | 58
> >> ++++++++++++++++++++++++++++++++++++++-----
> >> include/hw/vfio/vfio-common.h | 8 ++++++
> >> 2 files changed, 60 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> >> index d4959c036dd1..dc56cded2d95 100644
> >> --- a/hw/vfio/common.c
> >> +++ b/hw/vfio/common.c
> >> @@ -407,8 +407,8 @@ static bool
> >> vfio_listener_skipped_section(MemoryRegionSection *section)
> >> }
> >>
> >> /* Called with rcu_read_lock held. */
> >> -static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void **vaddr,
> >> - bool *read_only)
> >> +static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
> >> + ram_addr_t *ram_addr, bool *read_only)
> >> {
> >> MemoryRegion *mr;
> >> hwaddr xlat;
> >> @@ -439,8 +439,17 @@ static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void
> >> **vaddr,
> >> return false;
> >> }
> >>
> >> - *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> >> - *read_only = !writable || mr->readonly;
> >> + if (vaddr) {
> >> + *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> >> + }
> >> +
> >> + if (ram_addr) {
> >> + *ram_addr = memory_region_get_ram_addr(mr) + xlat;
> >> + }
> >> +
> >> + if (read_only) {
> >> + *read_only = !writable || mr->readonly;
> >> + }
> >>
> >> return true;
> >> }
> >> @@ -450,7 +459,6 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n,
> >> IOMMUTLBEntry *iotlb)
> >> VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
> >> VFIOContainer *container = giommu->container;
> >> hwaddr iova = iotlb->iova + giommu->iommu_offset;
> >> - bool read_only;
> >> void *vaddr;
> >> int ret;
> >>
> >> @@ -466,7 +474,10 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n,
> >> IOMMUTLBEntry *iotlb)
> >> rcu_read_lock();
> >>
> >> if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) {
> >> - if (!vfio_get_vaddr(iotlb, &vaddr, &read_only)) {
> >> + ram_addr_t ram_addr;
> >> + bool read_only;
> >> +
> >> + if (!vfio_get_xlat_addr(iotlb, &vaddr, &ram_addr, &read_only)) {
> >> goto out;
> >> }
> >> /*
> >> @@ -484,8 +495,28 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n,
> >> IOMMUTLBEntry *iotlb)
> >> "0x%"HWADDR_PRIx", %p) = %d (%m)",
> >> container, iova,
> >> iotlb->addr_mask + 1, vaddr, ret);
> >> + } else {
> >> + VFIOIovaRange *iova_range;
> >> +
> >> + iova_range = g_malloc0(sizeof(*iova_range));
> >> + iova_range->iova = iova;
> >> + iova_range->size = iotlb->addr_mask + 1;
> >> + iova_range->ram_addr = ram_addr;
> >> +
> >> + QLIST_INSERT_HEAD(&giommu->iova_list, iova_range, next);
> >> }
> >> } else {
> >> + VFIOIovaRange *iova_range, *tmp;
> >> +
> >> + QLIST_FOREACH_SAFE(iova_range, &giommu->iova_list, next, tmp) {
> >> + if (iova_range->iova >= iova &&
> >> + iova_range->iova + iova_range->size <= iova +
> >> + iotlb->addr_mask +
> >> 1) {
> >> + QLIST_REMOVE(iova_range, next);
> >> + g_free(iova_range);
> >> + }
> >> + }
> >> +
> >
> >
> > This is some pretty serious overhead... can't we trigger a replay when
> > migration is enabled to build this information then?
>
> Are you suggesting to call memory_region_iommu_replay() before
> vfio_sync_dirty_bitmap(), which would call vfio_iommu_map_notify() where
> iova list of mapping is maintained? Then in the notifer check if
> migration_is_running() and container->dirty_pages_supported == true,
> then only create iova mapping tree? In this case how would we know that
> this is triggered by
> vfio_sync_dirty_bitmap()
> -> memory_region_iommu_replay()
> and we don't have to call vfio_dma_map()?
memory_region_iommu_replay() calls a notifier of our choice, so we
could create a notifier specifically for creating this tree when dirty
logging is enabled. Thanks,
Alex
> > We're looking at
> > potentially thousands of entries, so a list is probably also not a good
> > choice.
>
> Changing it to tree.
>
> Thanks,
> Kirti
>
> I don't think it's acceptable to incur this even when not
> > migrating (ie. the vast majority of the time). Thanks,
> >
> > Alex
> >
> >> ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1);
> >> if (ret) {
> >> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", "
> >> @@ -642,6 +673,7 @@ static void vfio_listener_region_add(MemoryListener
> >> *listener,
> >> g_free(giommu);
> >> goto fail;
> >> }
> >> + QLIST_INIT(&giommu->iova_list);
> >> QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
> >> memory_region_iommu_replay(giommu->iommu, &giommu->n);
> >>
> >> @@ -740,6 +772,13 @@ static void vfio_listener_region_del(MemoryListener
> >> *listener,
> >> QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> >> if (MEMORY_REGION(giommu->iommu) == section->mr &&
> >> giommu->n.start == section->offset_within_region) {
> >> + VFIOIovaRange *iova_range, *tmp;
> >> +
> >> + QLIST_FOREACH_SAFE(iova_range, &giommu->iova_list, next,
> >> tmp) {
> >> + QLIST_REMOVE(iova_range, next);
> >> + g_free(iova_range);
> >> + }
> >> +
> >> memory_region_unregister_iommu_notifier(section->mr,
> >> &giommu->n);
> >> QLIST_REMOVE(giommu, giommu_next);
> >> @@ -1541,6 +1580,13 @@ static void vfio_disconnect_container(VFIOGroup
> >> *group)
> >> QLIST_REMOVE(container, next);
> >>
> >> QLIST_FOREACH_SAFE(giommu, &container->giommu_list, giommu_next,
> >> tmp) {
> >> + VFIOIovaRange *iova_range, *itmp;
> >> +
> >> + QLIST_FOREACH_SAFE(iova_range, &giommu->iova_list, next,
> >> itmp) {
> >> + QLIST_REMOVE(iova_range, next);
> >> + g_free(iova_range);
> >> + }
> >> +
> >> memory_region_unregister_iommu_notifier(
> >> MEMORY_REGION(giommu->iommu), &giommu->n);
> >> QLIST_REMOVE(giommu, giommu_next);
> >> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> >> index 0a1651eda2d0..aa7524fe2cc5 100644
> >> --- a/include/hw/vfio/vfio-common.h
> >> +++ b/include/hw/vfio/vfio-common.h
> >> @@ -89,11 +89,19 @@ typedef struct VFIOContainer {
> >> QLIST_ENTRY(VFIOContainer) next;
> >> } VFIOContainer;
> >>
> >> +typedef struct VFIOIovaRange {
> >> + hwaddr iova;
> >> + size_t size;
> >> + ram_addr_t ram_addr;
> >> + QLIST_ENTRY(VFIOIovaRange) next;
> >> +} VFIOIovaRange;
> >> +
> >> typedef struct VFIOGuestIOMMU {
> >> VFIOContainer *container;
> >> IOMMUMemoryRegion *iommu;
> >> hwaddr iommu_offset;
> >> IOMMUNotifier n;
> >> + QLIST_HEAD(, VFIOIovaRange) iova_list;
> >> QLIST_ENTRY(VFIOGuestIOMMU) giommu_next;
> >> } VFIOGuestIOMMU;
> >>
> >
>