Re: [PATCH 9.0 00/13] Consolidate common vdpa members in VhostVDPAShared

[Jason Wang]

On Sat, Nov 25, 2023 at 1:14 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Current memory operations like pinning may take a lot of time at the
> destination.  Currently they are done after the source of the migration is
> stopped, and before the workload is resumed at the destination.  This is a
> period where neigher traffic can flow, nor the VM workload can continue
> (downtime).
>
> We can do better as we know the memory layout of the guest RAM at the
> destination from the moment the migration starts.  Moving that operation 
> allows
> QEMU to communicate the kernel the maps while the workload is still running in
> the source, so Linux can start mapping them.  Ideally, all IOMMU is 
> configured,
> but if the vDPA parent driver uses on-chip IOMMU and .set_map we're still
> saving all the pinning time.
>
> This is a first required step to consolidate all the members in a common
> struct.  This is needed because the destination does not know what vhost_vdpa
> struct will have the registered listener member, so it is easier to place them
> in a shared struct rather to keep them in vhost_vdpa struct.
>
> v1 from RFC:
> * Fix vhost_vdpa_net_cvq_start checking for always_svq instead of
>   shadow_data.  This could cause CVQ not being shadowed if
>   vhost_vdpa_net_cvq_start was called in the middle of a migration.

With the renaming of the VhostVDPAShared to VhostVDPAParent.

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

>
> Eugenio Pérez (13):
>   vdpa: add VhostVDPAShared
>   vdpa: move iova tree to the shared struct
>   vdpa: move iova_range to vhost_vdpa_shared
>   vdpa: move shadow_data to vhost_vdpa_shared
>   vdpa: use vdpa shared for tracing
>   vdpa: move file descriptor to vhost_vdpa_shared
>   vdpa: move iotlb_batch_begin_sent to vhost_vdpa_shared
>   vdpa: move backend_cap to vhost_vdpa_shared
>   vdpa: remove msg type of vhost_vdpa
>   vdpa: move iommu_list to vhost_vdpa_shared
>   vdpa: use VhostVDPAShared in vdpa_dma_map and unmap
>   vdpa: use dev_shared in vdpa_iommu
>   vdpa: move memory listener to vhost_vdpa_shared
>
>  include/hw/virtio/vhost-vdpa.h |  36 +++++---
>  hw/virtio/vdpa-dev.c           |   7 +-
>  hw/virtio/vhost-vdpa.c         | 160 +++++++++++++++++----------------
>  net/vhost-vdpa.c               | 117 ++++++++++++------------
>  hw/virtio/trace-events         |  14 +--
>  5 files changed, 174 insertions(+), 160 deletions(-)
>
> --
> 2.39.3
>
>