vhost-vdpa devices can return this feature now that blockers have been
set in case some features are not met.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230303172445.1089785-15-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Next patches enable devices to be migrated even if vdpa netdev has not
been started with x-svq. However, not all devices are migratable, so we
need to block migration if we detect that.
Block migration if we detect the device expose a feature SVQ does not
know how to work with.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-13-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Devices with CVQ need to migrate state beyond vq state. Leaving this to
future series.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-11-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Although it does not make a big difference, its more correct and
simplifies the cleanup path in subsequent patches.
Move ram_block_discard_disable(false) call to the top of
vhost_vdpa_cleanup because:
* We cannot use vhost_vdpa_first_dev after dev->opaque = NULL
assignment.
* Improve the stack order in cleanup: since it is the last action taken
in init, it should be the first at cleanup.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-10-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The function vhost.c:vhost_dev_stop calls vhost operation
vhost_dev_start(false). In the case of vdpa it totally reset and wipes
the device, making the fetching of the vring base (virtqueue state) totally
useless.
The kernel backend does not use vhost_dev_start vhost op callback, but
vhost-user do. A patch to make vhost_user_dev_start more similar to vdpa
is desirable, but it can be added on top.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-8-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The function vhost.c:vhost_dev_stop fetches the vring base so the vq
state can be migrated to other devices. However, this is unreliable in
vdpa, since we didn't signal the device to suspend the queues, making
the value fetched useless.
Suspend the device if possible before fetching first and subsequent
vring bases.
Moreover, vdpa totally reset and wipes the device at the last device
before fetch its vrings base, making that operation useless in the last
device. This will be fixed in later patches of this series.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-7-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This allows vhost_vdpa to track if it is safe to get the vring base from
the device or not. If it is not, vhost can fall back to fetch idx from
the guest buffer again.
No functional change intended in this patch, later patches will use this
field.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-6-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
At this moment it is only possible to migrate to a vdpa device running
with x-svq=on. As a protective measure, the rewind of the inflight
descriptors was done at the destination. That way if the source sent a
virtqueue with inuse descriptors they are always discarded.
Since this series allows to migrate also to passthrough devices with no
SVQ, the right thing to do is to rewind at the source so the base of
vrings are correct.
Support for inflight descriptors may be added in the future.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230303172445.1089785-5-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This is needed for qemu to know it can suspend the device to retrieve
its status and enable SVQ with it, so all the process is transparent to
the guest.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230303172445.1089785-4-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
As SVQ can be enabled dynamically at any time, it needs to store call fd
always.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-3-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Not stopping them leave the device in a bad state when virtio-net
fronted device is unplugged with device_del monitor command.
This is not triggable in regular poweroff or qemu forces shutdown
because cleanup is called right after vhost_vdpa_dev_start(false). But
devices hot unplug does not call vdpa device cleanups. This lead to all
the vhost_vdpa devices without stop the SVQ but the last.
Fix it and clean the code, making it symmetric with
vhost_vdpa_svqs_start.
Fixes: dff4426fa6 ("vhost: Add Shadow VirtQueue kick forwarding capabilities")
Reported-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230209170004.899472-1-eperezma@redhat.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
This allows the vhost-vdpa device to batch the setup of all its MRs of
host notifiers.
This significantly reduces the device starting time, e.g. the time spend
on setup the host notifier MRs reduce from 423ms to 32ms for a VM with
64 vCPUs and 3 vhost-vDPA generic devices (vdpa_sim_blk, 64vq per device).
Signed-off-by: Longpeng <longpeng2@huawei.com>
Message-Id: <20221227072015.3134-4-longpeng2@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
In commit a585fad26b ("vdpa: request iova_range only once") we remove
GET_IOVA_RANGE form vhost_vdpa_init, the generic vdpa device will start
without iova_range populated, so the device won't work. Let's call
GET_IOVA_RANGE ioctl explicitly.
Fixes: a585fad26b ("vdpa: request iova_range only once")
Signed-off-by: Longpeng <longpeng2@huawei.com>
Message-Id: <20221224114848.3062-2-longpeng2@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Add new call back function in vhost-vdpa, The function
vhost_set_config_call can set the event fd to kernel.
This function will be called in the vhost_dev_start
and vhost_dev_stop
Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20221222070451.936503-6-lulu@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Isolate control virtqueue in its own group, allowing to intercept control
commands but letting dataplane run totally passthrough to the guest.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20221215113144.322011-13-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
The memory listener that thells the device how to convert GPA to qemu's
va is registered against CVQ vhost_vdpa. memory listener translations
are always ASID 0, CVQ ones are ASID 1 if supported.
Let's tell the listener if it needs to register them on iova tree or
not.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-12-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
So the caller can choose which ASID is destined.
No need to update the batch functions as they will always be called from
memory listener updates at the moment. Memory listener updates will
always update ASID 0, as it's the passthrough ASID.
All vhost devices's ASID are 0 at this moment.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-10-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
SVQ may run or not in a device depending on runtime conditions (for
example, if the device can move CVQ to its own group or not).
Allocate the SVQ array unconditionally at startup, since its hard to
move this allocation elsewhere.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-9-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The next patches will start control SVQ if possible. However, we don't
know if that will be possible at qemu boot anymore.
Since the moved checks will be already evaluated at net/ to know if it
is ok to shadow CVQ, move them.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-8-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Currently iova range is requested once per queue pair in the case of
net. Reduce the number of ioctls asking it once at initialization and
reusing that value for each vhost_vdpa.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20221215113144.322011-7-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasonwang@redhat.com>
Since we don't know if we will use SVQ at qemu initialization, let's
allocate iova_tree only if needed. To do so, accept it at SVQ start, not
at initialization.
This will avoid to create it if the device does not support SVQ.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-5-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The next patches will start control SVQ if possible. However, we don't
know if that will be possible at qemu boot anymore.
Delay device file descriptors until we know it at device start. This
will avoid to create them if the device does not support SVQ.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-4-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This function used to trust in v->shadow_vqs != NULL to know if it must
start svq or not.
This is not going to be valid anymore, as qemu is going to allocate svq
array unconditionally (but it will only start them conditionally).
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221215113144.322011-2-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
include/qapi/error.h advises to put ERRP_GUARD() right at the
beginning of the function, because only then can it guard the whole
function. Clean up the few spots disregarding the advice.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221121085054.683122-4-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
We can restore the device state in the destination via CVQ now. Remove
the migration blocker.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reduce code duplication.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Nothing actually reads the return value, but an error in cleaning some
entries could cause device stop to abort, making a restart impossible.
Better ignore explicitely the return value.
Reported-by: Lei Yang <leiyang@redhat.com>
Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Although the device will be reset before usage, the right thing to do is
to clean it.
Reported-by: Lei Yang <leiyang@redhat.com>
Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
It's convenient to call iova_tree_remove from a map returned from
iova_tree_find or iova_tree_find_iova. With the current code this is not
possible, since we will free it, and then we will try to search for it
again.
Fix it making accepting the map by value, forcing a copy of the
argument. Not applying a fixes tag, since there is no use like that at
the moment.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
If a map fails for whatever reason, it must not be saved in the tree.
Otherwise, qemu will try to unmap it in cleanup, leaving to more errors.
Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
Reported-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Next patch will skip the registering of dma maps that the vdpa device
rejects in the iova tree. We need to consider that here or we cause a
SIGSEGV accessing result.
Reported-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
vhost_vdpa_listener_region_del is always deleting the first iova entry
of the tree, since it's using the needle iova instead of the result's
one.
This was detected using a vga virtual device in the VM using vdpa SVQ.
It makes some extra memory adding and deleting, so the wrong one was
mapped / unmapped. This was undetected before since all the memory was
mappend and unmapped totally without that device, but other conditions
could trigger it too:
* mem_region was with .iova = 0, .translated_addr = (correct GPA).
* iova_tree_find_iova returned right result, but does not update
mem_region.
* iova_tree_remove always removed region with .iova = 0. Right iova were
sent to the device.
* Next map will fill the first region with .iova = 0, causing a mapping
with the same iova and device complains, if the next action is a map.
* Next unmap will cause to try to unmap again iova = 0, causing the
device to complain that no region was mapped at iova = 0.
Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
Reported-by: Lei Yang <leiyang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
The SVQ vring used idx usually match with the guest visible one, as long
as all the guest buffers (GPA) maps to exactly one buffer within qemu's
VA. However, as we can see in virtqueue_map_desc, a single guest buffer
could map to many buffers in SVQ vring.
Also, its also a mistake to rewind them at the source of migration.
Since VirtQueue is able to migrate the inflight descriptors, its
responsability of the destination to perform the rewind just in case it
cannot report the inflight descriptors to the device.
This makes easier to migrate between backends or to recover them in
vhost devices that support set in flight descriptors.
Fixes: 6d0b222666 ("vdpa: Adapt vhost_vdpa_get_vring_base to SVQ")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Since the vhost-vdpa device is exposing _F_LOG, adding a migration blocker if
it uses CVQ.
However, qemu is able to migrate simple devices with no CVQ as long as
they use SVQ. To allow it, add a placeholder error to vhost_vdpa, and
only add to vhost_dev when used. vhost_dev machinery place the migration
blocker if needed.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Do a simple forwarding of CVQ buffers, the same work SVQ could do but
through callbacks. No functional change intended.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Shadow CVQ will copy buffers on qemu VA, so we avoid TOCTOU attacks from
the guest that could set a different state in qemu device model and vdpa
device.
To do so, it needs to be able to map these new buffers to the device.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This allows external handlers to be aware of new buffers that the guest
places in the virtqueue.
When this callback is defined the ownership of the guest's virtqueue
element is transferred to the callback. This means that if the user
wants to forward the descriptor it needs to manually inject it. The
callback is also free to process the command by itself and use the
element with svq_push.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
The name vhost_vdpa_one_time_request() was confusing. No
matter whatever it returns, its typical occurrence had
always been at requests that only need to be applied once.
And the name didn't suggest what it actually checks for.
Change it to vhost_vdpa_first_dev() with polarity flipped
for better readibility of code. That way it is able to
reflect what the check is really about.
This call is applicable to request which performs operation
only once, before queues are set up, and usually at the beginning
of the caller function. Document the requirement for it in place.
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Message-Id: <1651890498-24478-7-git-send-email-si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
The vhost_vdpa_one_time_request() branch in
vhost_vdpa_set_backend_cap() incorrectly sends down
ioctls on vhost_dev with non-zero index. This may
end up with multiple VHOST_SET_BACKEND_FEATURES
ioctl calls sent down on the vhost-vdpa fd that is
shared between all these vhost_dev's.
To fix it, send down ioctl only once via the first
vhost_dev with index 0. Toggle the polarity of the
vhost_vdpa_one_time_request() test should do the
trick.
Fixes: 4d191cfdc7 ("vhost-vdpa: classify one time request")
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <1651890498-24478-6-git-send-email-si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
With the introduction of MQ the index of the vq needs to be calculated
with the device model vq_index.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220512175747.142058-5-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: 6d0b222666 ("vdpa: Adapt vhost_vdpa_get_vring_base to SVQ")
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20220512175747.142058-4-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Replace the global variables with inlined helper functions. getpagesize() is very
likely annotated with a "const" function attribute (at least with glibc), and thus
optimization should apply even better.
This avoids the need for a constructor initialization too.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220323155743.1585078-12-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SVQ is able to log the dirty bits by itself, so let's use it to not
block migration.
Also, ignore set and clear of VHOST_F_LOG_ALL on set_features if SVQ is
enabled. Even if the device supports it, the reports would be nonsense
because SVQ memory is in the qemu region.
The log region is still allocated. Future changes might skip that, but
this series is already long enough.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Setting the log address would make the device start reporting invalid
dirty memory because the SVQ vrings are located in qemu's memory.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This is needed to achieve migration, so the destination can restore its
index.
Setting base as last used idx, so destination will see as available all
the entries that the device did not use, including the in-flight
processing ones.
This is ok for networking, but other kinds of devices might have
problems with these retransmissions.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Use translations added in VhostIOVATree in SVQ.
Only introduce usage here, not allocation and deallocation. As with
previous patches, we use the dead code paths of shadow_vqs_enabled to
avoid commiting too many changes at once. These are impossible to take
at the moment.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Initial version of shadow virtqueue that actually forward buffers. There
is no iommu support at the moment, and that will be addressed in future
patches of this series. Since all vhost-vdpa devices use forced IOMMU,
this means that SVQ is not usable at this point of the series on any
device.
For simplicity it only supports modern devices, that expects vring
in little endian, with split ring and no event idx or indirect
descriptors. Support for them will not be added in this series.
It reuses the VirtQueue code for the device part. The driver part is
based on Linux's virtio_ring driver, but with stripped functionality
and optimizations so it's easier to review.
However, forwarding buffers have some particular pieces: One of the most
unexpected ones is that a guest's buffer can expand through more than
one descriptor in SVQ. While this is handled gracefully by qemu's
emulated virtio devices, it may cause unexpected SVQ queue full. This
patch also solves it by checking for this condition at both guest's
kicks and device's calls. The code may be more elegant in the future if
SVQ code runs in its own iocontext.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
