Messages in this thread | | | From | Eugenio Perez Martin <> | Date | Wed, 11 Oct 2023 13:30:10 +0200 | Subject | Re: [PATCH 0/4] vdpa: decouple reset of iotlb mapping from device reset |
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On Tue, Oct 10, 2023 at 11:05 AM Si-Wei Liu <si-wei.liu@oracle.com> wrote: > > In order to reduce needlessly high setup and teardown cost > of iotlb mapping during live migration, it's crucial to > decouple the vhost-vdpa iotlb abstraction from the virtio > device life cycle, i.e. iotlb mappings should be left > intact across virtio device reset [1]. For it to work, the > on-chip IOMMU parent device could implement a separate > .reset_map() operation callback to restore 1:1 DMA mapping > without having to resort to the .reset() callback, the > latter of which is mainly used to reset virtio device state. > This new .reset_map() callback will be invoked only before > the vhost-vdpa driver is to be removed and detached from > the vdpa bus, such that other vdpa bus drivers, e.g. > virtio-vdpa, can start with 1:1 DMA mapping when they > are attached. For the context, those on-chip IOMMU parent > devices, create the 1:1 DMA mapping at vdpa device creation, > and they would implicitly destroy the 1:1 mapping when > the first .set_map or .dma_map callback is invoked. > > This patchset is based off of the descriptor group v3 series > from Dragos. [2] > > [1] Reducing vdpa migration downtime because of memory pin / maps > https://www.mail-archive.com/qemu-devel@nongnu.org/msg953755.html > [2] [PATCH vhost v3 00/16] vdpa: Add support for vq descriptor mappings > https://lore.kernel.org/lkml/20231009112401.1060447-1-dtatulea@nvidia.com/ >
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Thanks!
> --- > v1: > - rewrote commit messages to include more detailed description and background > - reword to vendor specific IOMMU implementation from on-chip IOMMU > - include parent device backend feautres to persistent iotlb precondition > - reimplement mlx5_vdpa patch on top of descriptor group series > > RFC v3: > - fix missing return due to merge error in patch #4 > > RFC v2: > - rebased on top of the "[PATCH RFC v2 0/3] vdpa: dedicated descriptor table group" series: > https://lore.kernel.org/virtualization/1694248959-13369-1-git-send-email-si-wei.liu@oracle.com/ > > --- > > Si-Wei Liu (4): > vdpa: introduce .reset_map operation callback > vhost-vdpa: reset vendor specific mapping to initial state in .release > vhost-vdpa: introduce IOTLB_PERSIST backend feature bit > vdpa/mlx5: implement .reset_map driver op > > drivers/vdpa/mlx5/core/mlx5_vdpa.h | 1 + > drivers/vdpa/mlx5/core/mr.c | 17 +++++++++++++++++ > drivers/vdpa/mlx5/net/mlx5_vnet.c | 18 +++++++++++++----- > drivers/vhost/vdpa.c | 31 +++++++++++++++++++++++++++++++ > include/linux/vdpa.h | 10 ++++++++++ > include/uapi/linux/vhost_types.h | 2 ++ > 6 files changed, 74 insertions(+), 5 deletions(-) > > -- > 1.8.3.1 >
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