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From:   sebastien.boeuf@intel.com
To:     linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Cc:     mst@redhat.com, jasowang@redhat.com, eperezma@redhat.com,
        sebastien.boeuf@intel.com
Subject: [PATCH v4 0/4] vdpa: Add resume operation
Date:   Tue, 18 Oct 2022 10:37:23 +0200
Message-Id: <cover.1666082013.git.sebastien.boeuf@intel.com>
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From: Sebastien Boeuf <sebastien.boeuf@intel.com>

This series introduces a new operation for vdpa devices. It allows them
to be resumed after they have been suspended. A new feature bit is
introduced for devices to advertise their ability to be resumed after
they have been suspended. This feature bit is different from the one
advertising the ability to be suspended, meaning a device that can be
suspended might not have the ability to be resumed.

Even if it is already possible to restore a device that has been
suspended, which is very convenient for live migrating virtual machines,
there is a major drawback as the device must be fully reset. There is no
way to resume a device that has been suspended without having to
configure the device again and without having to recreate the IOMMU
mappings. This new operation aims at filling this gap by allowing the
device to resume processing the virtqueue descriptors without having to
reset it. This is particularly useful for performing virtual machine
offline migration, also called snapshot/restore, as it allows a virtual
machine to resume to a running state after it was paused and a snapshot
of the entire system was taken.

Sebastien Boeuf (4):
  vdpa: Add resume operation
  vhost-vdpa: Introduce RESUME backend feature bit
  vhost-vdpa: uAPI to resume the device
  vdpa_sim: Implement resume vdpa op

 drivers/vdpa/vdpa_sim/vdpa_sim.c | 14 +++++++++++++
 drivers/vhost/vdpa.c             | 34 +++++++++++++++++++++++++++++++-
 include/linux/vdpa.h             |  6 +++++-
 include/uapi/linux/vhost.h       |  8 ++++++++
 include/uapi/linux/vhost_types.h |  2 ++
 5 files changed, 62 insertions(+), 2 deletions(-)

-- 
2.34.1

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