* Alex Williamson (alex.william...@redhat.com) wrote: > On Thu, 25 Jun 2020 20:31:12 +0530 > Kirti Wankhede <kwankh...@nvidia.com> wrote: > > > On 6/25/2020 12:26 AM, Alex Williamson wrote: > > > On Sun, 21 Jun 2020 01:51:24 +0530 > > > Kirti Wankhede <kwankh...@nvidia.com> wrote: > > > > > >> With vIOMMU, IO virtual address range can get unmapped while in pre-copy > > >> phase of migration. In that case, unmap ioctl should return pages pinned > > >> in that range and QEMU should find its correcponding guest physical > > >> addresses and report those dirty. > > >> > > >> Suggested-by: Alex Williamson <alex.william...@redhat.com> > > >> Signed-off-by: Kirti Wankhede <kwankh...@nvidia.com> > > >> Reviewed-by: Neo Jia <c...@nvidia.com> > > >> --- > > >> hw/vfio/common.c | 85 > > >> +++++++++++++++++++++++++++++++++++++++++++++++++++++--- > > >> 1 file changed, 81 insertions(+), 4 deletions(-) > > >> > > >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c > > >> index 0518cf228ed5..a06b8f2f66e2 100644 > > >> --- a/hw/vfio/common.c > > >> +++ b/hw/vfio/common.c > > >> @@ -311,11 +311,83 @@ static bool > > >> vfio_devices_are_stopped_and_saving(void) > > >> return true; > > >> } > > >> > > >> +static bool vfio_devices_are_running_and_saving(void) > > >> +{ > > >> + VFIOGroup *group; > > >> + VFIODevice *vbasedev; > > >> + > > >> + QLIST_FOREACH(group, &vfio_group_list, next) { > > > > > > Same as previous, I'm curious if we should instead be looking at > > > container granularity. It especially seems to make sense here where > > > we're unmapping from a container, so iterating every device in every > > > group seems excessive. > > > > > > > changing it with container argument. > > > > >> + QLIST_FOREACH(vbasedev, &group->device_list, next) { > > >> + if ((vbasedev->device_state & VFIO_DEVICE_STATE_SAVING) && > > >> + (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING)) { > > >> + continue; > > >> + } else { > > >> + return false; > > >> + } > > > > > > I'm also not sure about the polarity of this function, should it be if > > > any device is _SAVING we should report the dirty bitmap? For example, > > > what if we have a set of paried failover NICs where we intend to unplug > > > one just prior to stopping the devices, aren't we going to lose dirtied > > > pages with this logic that they all must be running and saving? Thanks, > > > > > > > If migration is initiated, is device unplug allowed? Ideally it > > shouldn't. If it is, then how QEMU handles data stream of device which > > doesn't exist at destination? > > include/hw/qdev-core.h > struct DeviceState { > ... > bool allow_unplug_during_migration; > > AIUI, the failover_pair_id device is likely to be a vfio-pci NIC, > otherwise they'd simply migrate the primary NIC, so there's a very good > chance that a user would configure a VM with a migratable mdev device > and an failover NIC so that they have high speed networking on either > end of the migration.
My understanding for that failover code is that happens right at the beginning of migration while we're still in MIGRATION_STATUS_SETUP; whether there's anything that enforces that is a different matter. But, in that case, I don't think you'd be interested in that dirtying. Dave > > _SAVING flag is set during pre-copy and stop-and-copy phase. Here we > > only want to track pages which are unmapped during pre-copy phase, i.e. > > when vCPU are running. In case of VM suspend /saveVM, there is no > > pre-copy phase, but ideally we shouldn't see unmaps when vCPUs are > > stopped, right? But still for safer side, since we know exact phase, I > > would prefer to check for _SAVING and _RUNNING flags. > > We can't have unmaps while vCPUs are stopped, but I think the failover > code allows that we can be in the pre-copy phase where not all devices > support migration. As coded here, it appears that dirty tracking of any > unmap while in that phase is lost. Thanks, > > Alex > > > > >> + } > > >> + } > > >> + return true; > > >> +} > > >> + > > >> +static int vfio_dma_unmap_bitmap(VFIOContainer *container, > > >> + hwaddr iova, ram_addr_t size, > > >> + IOMMUTLBEntry *iotlb) > > >> +{ > > >> + struct vfio_iommu_type1_dma_unmap *unmap; > > >> + struct vfio_bitmap *bitmap; > > >> + uint64_t pages = TARGET_PAGE_ALIGN(size) >> TARGET_PAGE_BITS; > > >> + int ret; > > >> + > > >> + unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap)); > > >> + > > >> + unmap->argsz = sizeof(*unmap) + sizeof(*bitmap); > > >> + unmap->iova = iova; > > >> + unmap->size = size; > > >> + unmap->flags |= VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP; > > >> + bitmap = (struct vfio_bitmap *)&unmap->data; > > >> + > > >> + /* > > >> + * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap > > >> of > > >> + * TARGET_PAGE_SIZE to mark those dirty. Hence set bitmap_pgsize to > > >> + * TARGET_PAGE_SIZE. > > >> + */ > > >> + > > >> + bitmap->pgsize = TARGET_PAGE_SIZE; > > >> + bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / > > >> + BITS_PER_BYTE; > > >> + > > >> + if (bitmap->size > container->max_dirty_bitmap_size) { > > >> + error_report("UNMAP: Size of bitmap too big 0x%llx", > > >> bitmap->size); > > >> + ret = -E2BIG; > > >> + goto unmap_exit; > > >> + } > > >> + > > >> + bitmap->data = g_try_malloc0(bitmap->size); > > >> + if (!bitmap->data) { > > >> + ret = -ENOMEM; > > >> + goto unmap_exit; > > >> + } > > >> + > > >> + ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap); > > >> + if (!ret) { > > >> + cpu_physical_memory_set_dirty_lebitmap((uint64_t *)bitmap->data, > > >> + iotlb->translated_addr, pages); > > >> + } else { > > >> + error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %m"); > > >> + } > > >> + > > >> + g_free(bitmap->data); > > >> +unmap_exit: > > >> + g_free(unmap); > > >> + return ret; > > >> +} > > >> + > > >> /* > > >> * DMA - Mapping and unmapping for the "type1" IOMMU interface used on > > >> x86 > > >> */ > > >> static int vfio_dma_unmap(VFIOContainer *container, > > >> - hwaddr iova, ram_addr_t size) > > >> + hwaddr iova, ram_addr_t size, > > >> + IOMMUTLBEntry *iotlb) > > >> { > > >> struct vfio_iommu_type1_dma_unmap unmap = { > > >> .argsz = sizeof(unmap), > > >> @@ -324,6 +396,11 @@ static int vfio_dma_unmap(VFIOContainer *container, > > >> .size = size, > > >> }; > > >> > > >> + if (iotlb && container->dirty_pages_supported && > > >> + vfio_devices_are_running_and_saving()) { > > >> + return vfio_dma_unmap_bitmap(container, iova, size, iotlb); > > >> + } > > >> + > > >> while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) { > > >> /* > > >> * The type1 backend has an off-by-one bug in the kernel > > >> (71a7d3d78e3c > > >> @@ -371,7 +448,7 @@ static int vfio_dma_map(VFIOContainer *container, > > >> hwaddr iova, > > >> * the VGA ROM space. > > >> */ > > >> if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 || > > >> - (errno == EBUSY && vfio_dma_unmap(container, iova, size) == 0 && > > >> + (errno == EBUSY && vfio_dma_unmap(container, iova, size, NULL) > > >> == 0 && > > >> ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) { > > >> return 0; > > >> } > > >> @@ -542,7 +619,7 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, > > >> IOMMUTLBEntry *iotlb) > > >> } > > >> } > > >> > > >> - ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1); > > >> + ret = vfio_dma_unmap(container, iova, iotlb->addr_mask + 1, > > >> iotlb); > > >> if (ret) { > > >> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > >> "0x%"HWADDR_PRIx") = %d (%m)", > > >> @@ -853,7 +930,7 @@ static void vfio_listener_region_del(MemoryListener > > >> *listener, > > >> } > > >> > > >> if (try_unmap) { > > >> - ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); > > >> + ret = vfio_dma_unmap(container, iova, int128_get64(llsize), > > >> NULL); > > >> if (ret) { > > >> error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > >> "0x%"HWADDR_PRIx") = %d (%m)", > > > > > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK