From b051a3f640e2efc95e9e23c5cb1bb5a4c07731e2 Mon Sep 17 00:00:00 2001 From: Avihai Horon Date: Thu, 16 Feb 2023 16:36:22 +0200 Subject: [PATCH] vfio/migration: Allow migration without VFIO IOMMU dirty tracking support MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 all pages 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 introduction of iommufd [1]. iommufd can 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 is not 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-v6-a196d26f289e+11787-iommufd_jgg@nvidia.com/ Signed-off-by: Avihai Horon Reviewed-by: Cédric Le Goater Reviewed-by: Juan Quintela Link: https://lore.kernel.org/r/20230216143630.25610-4-avihaih@nvidia.com Signed-off-by: Alex Williamson --- hw/vfio/common.c | 20 ++++++++++++++++++-- hw/vfio/migration.c | 3 +-- 2 files changed, 19 insertions(+), 4 deletions(-) diff --git a/hw/vfio/common.c b/hw/vfio/common.c index 130e5d1dc7..f6dd571549 100644 --- a/hw/vfio/common.c +++ b/hw/vfio/common.c @@ -488,6 +488,12 @@ static int vfio_dma_unmap(VFIOContainer *container, return -errno; } + if (iotlb && vfio_devices_all_running_and_saving(container)) { + cpu_physical_memory_set_dirty_range(iotlb->translated_addr, size, + tcg_enabled() ? DIRTY_CLIENTS_ALL : + DIRTY_CLIENTS_NOCODE); + } + return 0; } @@ -1201,6 +1207,10 @@ 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 { @@ -1236,6 +1246,13 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova, uint64_t pages; int ret; + if (!container->dirty_pages_supported) { + cpu_physical_memory_set_dirty_range(ram_addr, size, + tcg_enabled() ? DIRTY_CLIENTS_ALL : + DIRTY_CLIENTS_NOCODE); + return 0; + } + dbitmap = g_malloc0(sizeof(*dbitmap) + sizeof(*range)); dbitmap->argsz = sizeof(*dbitmap) + sizeof(*range); @@ -1409,8 +1426,7 @@ 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 65f3f3bef7..e56eef1ee8 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -858,11 +858,10 @@ 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; } -- 2.11.0