On Fri, Oct 29, 2021 at 8:41 PM Eugenio Pérez <epere...@redhat.com> wrote: > > This series enable shadow virtqueue (SVQ) for vhost-vdpa devices. This > is intended as a new method of tracking the memory the devices touch > during a migration process: Instead of relay on vhost device's dirty > logging capability, SVQ intercepts the VQ dataplane forwarding the > descriptors between VM and device. This way qemu is the effective > writer of guests memory, like in qemu's virtio device operation. > > When SVQ is enabled qemu offers a new virtual address space to the > device to read and write into, and it maps new vrings and the guest > memory in it. SVQ also intercepts kicks and calls between the device > and the guest. Used buffers relay would cause dirty memory being > tracked, but at this RFC SVQ is not enabled on migration automatically. > > Thanks of being a buffers relay system, SVQ can be used also to > communicate devices and drivers with different capabilities, like > devices that only supports packed vring and not split and old guest > with no driver packed support. > > It is based on the ideas of DPDK SW assisted LM, in the series of > DPDK's https://patchwork.dpdk.org/cover/48370/ . However, these does > not map the shadow vq in guest's VA, but in qemu's. > > For qemu to use shadow virtqueues the guest virtio driver must not use > features like event_idx. > > SVQ needs to be enabled with QMP command: > > { "execute": "x-vhost-set-shadow-vq", > "arguments": { "name": "vhost-vdpa0", "enable": true } } > > This series includes some patches to delete in the final version that > helps with its testing. The first two of the series have been sent > sepparately but they haven't been included in qemu main branch. > > The two after them adds the feature to stop the device and be able to > set and get its status. It's intended to be used with vp_vpda driver in > a nested environment, so they are also external to this series. The > vp_vdpa driver also need modifications to forward the new status bit, > they will be proposed sepparately > > Patches 5-12 prepares the SVQ and QMP command to support guest to host > notifications forwarding. If the SVQ is enabled with these ones > applied and the device supports it, that part can be tested in > isolation (for example, with networking), hopping through SVQ. > > Same thing is true with patches 13-17, but with device to guest > notifications. > > Based on them, patches from 18 to 22 implement the actual buffer > forwarding, using some features already introduced in previous. > However, they will need a host device with no iommu, something that > is not available at the moment. > > The last part of the series uses properly the host iommu, so the driver > can access this new virtual address space created. > > Comments are welcome. > > TODO: > * Event, indirect, packed, and others features of virtio. > * To sepparate buffers forwarding in its own AIO context, so we can > throw more threads to that task and we don't need to stop the main > event loop. > * Support multiqueue virtio-net vdpa. > * Proper documentation. > > Changes from v4 RFC: > * Support of allocating / freeing iova ranges in IOVA tree. Extending > already present iova-tree for that. > * Proper validation of guest features. Now SVQ can negotiate a > different set of features with the device when enabled. > * Support of host notifiers memory regions > * Handling of SVQ full queue in case guest's descriptors span to > different memory regions (qemu's VA chunks). > * Flush pending used buffers at end of SVQ operation. > * QMP command now looks by NetClientState name. Other devices will need > to implement it's way to enable vdpa. > * Rename QMP command to set, so it looks more like a way of working > * Better use of qemu error system > * Make a few assertions proper error-handling paths. > * Add more documentation > * Less coupling of virtio / vhost, that could cause friction on changes > * Addressed many other small comments and small fixes. > > Changes from v3 RFC: > * Move everything to vhost-vdpa backend. A big change, this allowed > some cleanup but more code has been added in other places. > * More use of glib utilities, especially to manage memory. > v3 link: > https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg06032.html > > Changes from v2 RFC: > * Adding vhost-vdpa devices support > * Fixed some memory leaks pointed by different comments > v2 link: > https://lists.nongnu.org/archive/html/qemu-devel/2021-03/msg05600.html > > Changes from v1 RFC: > * Use QMP instead of migration to start SVQ mode. > * Only accepting IOMMU devices, closer behavior with target devices > (vDPA) > * Fix invalid masking/unmasking of vhost call fd. > * Use of proper methods for synchronization. > * No need to modify VirtIO device code, all of the changes are > contained in vhost code. > * Delete superfluous code. > * An intermediate RFC was sent with only the notifications forwarding > changes. It can be seen in > https://patchew.org/QEMU/20210129205415.876290-1-epere...@redhat.com/ > v1 link: > https://lists.gnu.org/archive/html/qemu-devel/2020-11/msg05372.html > > Eugenio Pérez (20): > virtio: Add VIRTIO_F_QUEUE_STATE > virtio-net: Honor VIRTIO_CONFIG_S_DEVICE_STOPPED > virtio: Add virtio_queue_is_host_notifier_enabled > vhost: Make vhost_virtqueue_{start,stop} public > vhost: Add x-vhost-enable-shadow-vq qmp > vhost: Add VhostShadowVirtqueue > vdpa: Register vdpa devices in a list > vhost: Route guest->host notification through shadow virtqueue > Add vhost_svq_get_svq_call_notifier > Add vhost_svq_set_guest_call_notifier > vdpa: Save call_fd in vhost-vdpa > vhost-vdpa: Take into account SVQ in vhost_vdpa_set_vring_call > vhost: Route host->guest notification through shadow virtqueue > virtio: Add vhost_shadow_vq_get_vring_addr > vdpa: Save host and guest features > vhost: Add vhost_svq_valid_device_features to shadow vq > vhost: Shadow virtqueue buffers forwarding > vhost: Add VhostIOVATree > vhost: Use a tree to store memory mappings > vdpa: Add custom IOTLB translations to SVQ > > Eugenio Pérez (26): > util: Make some iova_tree parameters const > vhost: Fix last queue index of devices with no cvq > virtio: Add VIRTIO_F_QUEUE_STATE > virtio-net: Honor VIRTIO_CONFIG_S_DEVICE_STOPPED > vhost: Add x-vhost-set-shadow-vq qmp > vhost: Add VhostShadowVirtqueue > vdpa: Save kick_fd in vhost-vdpa > vdpa: Add vhost_svq_get_dev_kick_notifier > vdpa: Add vhost_svq_set_svq_kick_fd > vhost: Add Shadow VirtQueue kick forwarding capabilities > vhost: Handle host notifiers in SVQ > vhost: Route guest->host notification through shadow virtqueue > Add vhost_svq_get_svq_call_notifier > Add vhost_svq_set_guest_call_notifier > vdpa: Save call_fd in vhost-vdpa > vhost-vdpa: Take into account SVQ in vhost_vdpa_set_vring_call > vhost: Route host->guest notification through shadow virtqueue > virtio: Add vhost_shadow_vq_get_vring_addr > vdpa: ack VIRTIO_F_QUEUE_STATE if device supports it > vhost: Add vhost_svq_valid_device_features to shadow vq > vhost: Add vhost_svq_valid_guest_features to shadow vq > vhost: Shadow virtqueue buffers forwarding > util: Add iova_tree_alloc > vhost: Add VhostIOVATree > vhost: Use a tree to store memory mappings > vdpa: Add custom IOTLB translations to SVQ > > qapi/net.json | 20 + > hw/virtio/vhost-iova-tree.h | 27 + > hw/virtio/vhost-shadow-virtqueue.h | 44 ++ > hw/virtio/virtio-pci.h | 1 + > include/hw/virtio/vhost-vdpa.h | 12 + > include/hw/virtio/virtio.h | 4 +- > include/qemu/iova-tree.h | 25 +- > .../standard-headers/linux/virtio_config.h | 5 + > include/standard-headers/linux/virtio_pci.h | 2 + > hw/i386/intel_iommu.c | 2 +- > hw/net/vhost_net.c | 2 +- > hw/net/virtio-net.c | 6 +- > hw/virtio/vhost-iova-tree.c | 157 ++++ > hw/virtio/vhost-shadow-virtqueue.c | 746 ++++++++++++++++++ > hw/virtio/vhost-vdpa.c | 437 +++++++++- > hw/virtio/virtio-pci.c | 16 +- > net/vhost-vdpa.c | 28 + > util/iova-tree.c | 151 +++- > hw/virtio/meson.build | 2 +- > 19 files changed, 1664 insertions(+), 23 deletions(-) > create mode 100644 hw/virtio/vhost-iova-tree.h > create mode 100644 hw/virtio/vhost-shadow-virtqueue.h > create mode 100644 hw/virtio/vhost-iova-tree.c > create mode 100644 hw/virtio/vhost-shadow-virtqueue.c > > -- > 2.27.0 > > >
To make the review easier, this tree is also at [1]. Thanks! [1] https://github.com/eugpermar/qemu/tree/vdpa_sw_live_migration.d/vdpa-v5
