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. > _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)", > > >