在 2023/3/30 18:42, Eugenio Perez Martin 写道:
On Thu, Mar 30, 2023 at 8:23 AM Jason Wang <jasow...@redhat.com> wrote:
On Thu, Mar 30, 2023 at 2:20 PM Jason Wang <jasow...@redhat.com> wrote:
On Fri, Mar 24, 2023 at 3:54 AM Eugenio Pérez <epere...@redhat.com> wrote:
Evaluating it at start time instead of initialization time may make the
guest capable of dynamically adding or removing migration blockers.
Also, moving to initialization reduces the number of ioctls in the
migration, reducing failure possibilities.
As a drawback we need to check for CVQ isolation twice: one time with no
MQ negotiated and another one acking it, as long as the device supports
it. This is because Vring ASID / group management is based on vq
indexes, but we don't know the index of CVQ before negotiating MQ.
We need to fail if we see a device that can isolate cvq without MQ but
not with MQ.
Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
v2: Take out the reset of the device from vhost_vdpa_cvq_is_isolated
---
net/vhost-vdpa.c | 194 ++++++++++++++++++++++++++++++++++++-----------
1 file changed, 151 insertions(+), 43 deletions(-)
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 4397c0d4b3..db2c9afcb3 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -43,6 +43,13 @@ typedef struct VhostVDPAState {
/* The device always have SVQ enabled */
bool always_svq;
+
+ /* The device can isolate CVQ in its own ASID if MQ is negotiated */
+ bool cvq_isolated_mq;
+
+ /* The device can isolate CVQ in its own ASID if MQ is not negotiated */
+ bool cvq_isolated;
As stated above, if we need a device that cvq_isolated_mq^cvq_isolated
== true, we need to fail. This may reduce the complexity of the code?
Thanks
Since we are the mediation layer, Qemu can alway choose to negotiate
MQ regardless whether or not it is supported by the guest. In this
way, we can have a stable virtqueue index for cvq.
I think it is a great idea and it simplifies this patch somehow.
However, we need something like the queue mapping [1] to do so :).
To double confirm:
* If the device supports MQ, only probe MQ. If not, only probe !MQ.
* Only store cvq_isolated in VhostVDPAState.
Now, if the device does not negotiate MQ but the device supports MQ:
I'm not sure I understand here, if device supports MQ it should accepts
MQ or we can fail the initialization here.
* All the requests to queue 3 must be redirected to the last queue in
the device. That includes set_vq_address, notifiers regions, etc.
This also means we will only mediate the case:
1) Qemu emulated virtio-net has 1 queue but device support multiple queue
but not
2) Qemu emulated virtio-net has M queue but device support N queue (N>M)
I'm totally ok to go this route but it's not immediate.
Yes but I mean, we can start from failing the device if
cvq_isolated_mq^cvq_isolated == true (or I wonder if we can meet this
condition for any existing parents).
Thanks
Thanks!
[1] https://lists.gnu.org/archive/html/qemu-devel/2023-01/msg07157.html
