On Thu, 3 Nov 2022 18:16:10 +0200 Avihai Horon <avih...@nvidia.com> wrote:
> Currently, if IOMMU of a VFIO container doesn't support dirty page > tracking, migration is blocked. This is because a DMA-able VFIO device > can dirty RAM pages without updating QEMU about it, thus breaking the > migration. > > However, this doesn't mean that migration can't be done at all. > In such case, allow migration and let QEMU VFIO code mark the entire > bitmap dirty. > > This guarantees that all pages that might have gotten dirty are reported > back, and thus guarantees a valid migration even without VFIO IOMMU > dirty tracking support. > > The motivation for this patch is the future introduction of iommufd [1]. > iommufd will directly implement the /dev/vfio/vfio container IOCTLs by > mapping them into its internal ops, allowing the usage of these IOCTLs > over iommufd. However, VFIO IOMMU dirty tracking will not be supported > by this VFIO compatibility API. > > This patch will allow migration by hosts that use the VFIO compatibility > API and prevent migration regressions caused by the lack of VFIO IOMMU > dirty tracking support. > > [1] https://lore.kernel.org/kvm/0-v2-f9436d0bde78+4bb-iommufd_...@nvidia.com/ > > Signed-off-by: Avihai Horon <avih...@nvidia.com> > --- > hw/vfio/common.c | 84 +++++++++++++++++++++++++++++++++++++-------- > hw/vfio/migration.c | 3 +- > 2 files changed, 70 insertions(+), 17 deletions(-) This duplicates quite a bit of code, I think we can integrate this into a common flow quite a bit more. See below, only compile tested. Thanks, Alex diff --git a/hw/vfio/common.c b/hw/vfio/common.c index 6b5d8c0bf694..4117b40fd9b0 100644 --- a/hw/vfio/common.c +++ b/hw/vfio/common.c @@ -397,17 +397,33 @@ static int vfio_dma_unmap_bitmap(VFIOContainer *container, IOMMUTLBEntry *iotlb) { struct vfio_iommu_type1_dma_unmap *unmap; - struct vfio_bitmap *bitmap; + struct vfio_bitmap *vbitmap; + unsigned long *bitmap; + uint64_t bitmap_size; uint64_t pages = REAL_HOST_PAGE_ALIGN(size) / qemu_real_host_page_size(); int ret; - unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap)); + unmap = g_malloc0(sizeof(*unmap) + sizeof(*vbitmap)); - unmap->argsz = sizeof(*unmap) + sizeof(*bitmap); + unmap->argsz = sizeof(*unmap); unmap->iova = iova; unmap->size = size; - unmap->flags |= VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP; - bitmap = (struct vfio_bitmap *)&unmap->data; + + bitmap_size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / + BITS_PER_BYTE; + bitmap = g_try_malloc0(bitmap_size); + if (!bitmap) { + ret = -ENOMEM; + goto unmap_exit; + } + + if (!container->dirty_pages_supported) { + bitmap_set(bitmap, 0, pages); + goto do_unmap; + } + + unmap->argsz += sizeof(*vbitmap); + unmap->flags = VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP; /* * cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of @@ -415,33 +431,28 @@ static int vfio_dma_unmap_bitmap(VFIOContainer *container, * to qemu_real_host_page_size. */ - bitmap->pgsize = qemu_real_host_page_size(); - bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / - BITS_PER_BYTE; + vbitmap = (struct vfio_bitmap *)&unmap->data; + vbitmap->data = (__u64 *)bitmap; + vbitmap->pgsize = qemu_real_host_page_size(); + vbitmap->size = bitmap_size; - if (bitmap->size > container->max_dirty_bitmap_size) { - error_report("UNMAP: Size of bitmap too big 0x%"PRIx64, - (uint64_t)bitmap->size); + if (bitmap_size > container->max_dirty_bitmap_size) { + error_report("UNMAP: Size of bitmap too big 0x%"PRIx64, bitmap_size); ret = -E2BIG; goto unmap_exit; } - bitmap->data = g_try_malloc0(bitmap->size); - if (!bitmap->data) { - ret = -ENOMEM; - goto unmap_exit; - } - +do_unmap: ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap); if (!ret) { - cpu_physical_memory_set_dirty_lebitmap((unsigned long *)bitmap->data, - iotlb->translated_addr, pages); + cpu_physical_memory_set_dirty_lebitmap(bitmap, iotlb->translated_addr, + pages); } else { error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %m"); } - g_free(bitmap->data); unmap_exit: + g_free(bitmap); g_free(unmap); return ret; } @@ -460,8 +471,7 @@ static int vfio_dma_unmap(VFIOContainer *container, .size = size, }; - if (iotlb && container->dirty_pages_supported && - vfio_devices_all_running_and_saving(container)) { + if (iotlb && vfio_devices_all_running_and_saving(container)) { return vfio_dma_unmap_bitmap(container, iova, size, iotlb); } @@ -1257,6 +1267,10 @@ static void vfio_set_dirty_page_tracking(VFIOContainer *container, bool start) .argsz = sizeof(dirty), }; + if (!container->dirty_pages_supported) { + return; + } + if (start) { dirty.flags = VFIO_IOMMU_DIRTY_PAGES_FLAG_START; } else { @@ -1287,11 +1301,26 @@ static void vfio_listener_log_global_stop(MemoryListener *listener) static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova, uint64_t size, ram_addr_t ram_addr) { - struct vfio_iommu_type1_dirty_bitmap *dbitmap; + struct vfio_iommu_type1_dirty_bitmap *dbitmap = NULL; struct vfio_iommu_type1_dirty_bitmap_get *range; + unsigned long *bitmap; + uint64_t bitmap_size; uint64_t pages; int ret; + pages = REAL_HOST_PAGE_ALIGN(size) / qemu_real_host_page_size(); + bitmap_size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / + BITS_PER_BYTE; + bitmap = g_try_malloc0(bitmap_size); + if (!bitmap) { + return -ENOMEM; + } + + if (!container->dirty_pages_supported) { + bitmap_set(bitmap, 0, pages); + goto set_dirty; + } + dbitmap = g_malloc0(sizeof(*dbitmap) + sizeof(*range)); dbitmap->argsz = sizeof(*dbitmap) + sizeof(*range); @@ -1306,15 +1335,8 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova, * to qemu_real_host_page_size. */ range->bitmap.pgsize = qemu_real_host_page_size(); - - pages = REAL_HOST_PAGE_ALIGN(range->size) / qemu_real_host_page_size(); - range->bitmap.size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / - BITS_PER_BYTE; - range->bitmap.data = g_try_malloc0(range->bitmap.size); - if (!range->bitmap.data) { - ret = -ENOMEM; - goto err_out; - } + range->bitmap.size = bitmap_size; + range->bitmap.data = (__u64 *)bitmap; ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, dbitmap); if (ret) { @@ -1324,13 +1346,13 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova, goto err_out; } - cpu_physical_memory_set_dirty_lebitmap((unsigned long *)range->bitmap.data, - ram_addr, pages); +set_dirty: + cpu_physical_memory_set_dirty_lebitmap(bitmap, ram_addr, pages); - trace_vfio_get_dirty_bitmap(container->fd, range->iova, range->size, - range->bitmap.size, ram_addr); + trace_vfio_get_dirty_bitmap(container->fd, iova, size, + bitmap_size, ram_addr); err_out: - g_free(range->bitmap.data); + g_free(bitmap); g_free(dbitmap); return ret; @@ -1465,8 +1487,7 @@ static void vfio_listener_log_sync(MemoryListener *listener, { VFIOContainer *container = container_of(listener, VFIOContainer, listener); - if (vfio_listener_skipped_section(section) || - !container->dirty_pages_supported) { + if (vfio_listener_skipped_section(section)) { return; } diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index f5e72c7ac198..99ffb7578290 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -857,11 +857,10 @@ int64_t vfio_mig_bytes_transferred(void) int vfio_migration_probe(VFIODevice *vbasedev, Error **errp) { - VFIOContainer *container = vbasedev->group->container; struct vfio_region_info *info = NULL; int ret = -ENOTSUP; - if (!vbasedev->enable_migration || !container->dirty_pages_supported) { + if (!vbasedev->enable_migration) { goto add_blocker; }
