[Qemu-devel] [PATCH v2 0/2] vhost-user-bridge reconnect regression

[Qemu-devel] [PATCH v2 0/2] vhost-user-bridge reconnect regression

[Marc-André Lureau]

Hi,

libvhost-user doesn't support resuming with the same trick vubr had
since commit 523b018dde3b7650fe5401d0499b30cf2f117515. The following
two patches fix that regression.

Thanks

Marc-André Lureau (2):
  libvhost-user: support resuming vq->last_avail_idx based on used_idx
  vhost-user-bridge: fix resume regression (since 2.9)

 contrib/libvhost-user/libvhost-user.h |  7 +++++++
 contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
 tests/vhost-user-bridge.c             |  7 +++++++
 3 files changed, 27 insertions(+)

-- 
2.14.1.146.gd35faa819

[Qemu-devel] [PATCH v2 1/2] libvhost-user: support resuming vq->last_avail_idx based on used_idx

[Marc-André Lureau]

This is the same workaround as commit 523b018dde3b765, which was lost
with libvhost-user transition in commit e10e798c85c2331.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 contrib/libvhost-user/libvhost-user.h |  7 +++++++
 contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index 53ef222c0b..4021f1124e 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -132,6 +132,7 @@ typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
 typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
                                   int *do_reply);
 typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
+typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
 
 typedef struct VuDevIface {
     /* called by VHOST_USER_GET_FEATURES to get the features bitmask */
@@ -148,6 +149,12 @@ typedef struct VuDevIface {
     vu_process_msg_cb process_msg;
     /* tells when queues can be processed */
     vu_queue_set_started_cb queue_set_started;
+    /*
+     * If the queue is processed in order, in which case it will be
+     * resumed to vring.used->idx. This can help to support resuming
+     * on unmanaged exit/crash.
+     */
+    vu_queue_is_processed_in_order_cb queue_is_processed_in_order;
 } VuDevIface;
 
 typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 35fa0c5e56..d27d6303db 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -521,6 +521,19 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg)
 
     vq->used_idx = vq->vring.used->idx;
 
+    if (vq->last_avail_idx != vq->used_idx) {
+        bool resume = dev->iface->queue_is_processed_in_order &&
+            dev->iface->queue_is_processed_in_order(dev, index);
+
+        DPRINT("Last avail index != used index: %u != %u%s\n",
+               vq->last_avail_idx, vq->used_idx,
+               resume ? ", resuming" : "");
+
+        if (resume) {
+            vq->shadow_avail_idx = vq->last_avail_idx = vq->used_idx;
+        }
+    }
+
     return false;
 }
 
-- 
2.14.1.146.gd35faa819

[Qemu-devel] [PATCH v2 2/2] vhost-user-bridge: fix resume regression (since 2.9)

[Marc-André Lureau]

Commit e10e798c85c2331 switched to libvhost-user which lacked support
for resuming the avail_idx based on used_idx.

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=1485867

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 tests/vhost-user-bridge.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
index 1e5b5ca3da..f922cc75ae 100644
--- a/tests/vhost-user-bridge.c
+++ b/tests/vhost-user-bridge.c
@@ -466,11 +466,18 @@ vubr_panic(VuDev *dev, const char *msg)
     vubr->quit = 1;
 }
 
+static bool
+vubr_queue_is_processed_in_order(VuDev *dev, int qidx)
+{
+    return true;
+}
+
 static const VuDevIface vuiface = {
     .get_features = vubr_get_features,
     .set_features = vubr_set_features,
     .process_msg = vubr_process_msg,
     .queue_set_started = vubr_queue_set_started,
+    .queue_is_processed_in_order = vubr_queue_is_processed_in_order,
 };
 
 static void
-- 
2.14.1.146.gd35faa819

Re: [Qemu-devel] [PATCH v2 0/2] vhost-user-bridge reconnect regression

[Michael S. Tsirkin]

On Tue, Aug 29, 2017 at 05:27:49PM +0200, Marc-André Lureau wrote:
> Hi,
> 
> libvhost-user doesn't support resuming with the same trick vubr had
> since commit 523b018dde3b7650fe5401d0499b30cf2f117515. The following
> two patches fix that regression.


Thanks! Do we need this in 2.10? If not pls ping after 2.10 is out.

> Thanks
> 
> Marc-André Lureau (2):
>   libvhost-user: support resuming vq->last_avail_idx based on used_idx
>   vhost-user-bridge: fix resume regression (since 2.9)
> 
>  contrib/libvhost-user/libvhost-user.h |  7 +++++++
>  contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
>  tests/vhost-user-bridge.c             |  7 +++++++
>  3 files changed, 27 insertions(+)
> 
> -- 
> 2.14.1.146.gd35faa819

Re: [Qemu-devel] [PATCH v2 0/2] vhost-user-bridge reconnect regression

[Marc-André Lureau]

Hi

On Tue, Aug 29, 2017 at 5:34 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Tue, Aug 29, 2017 at 05:27:49PM +0200, Marc-André Lureau wrote:
>> Hi,
>>
>> libvhost-user doesn't support resuming with the same trick vubr had
>> since commit 523b018dde3b7650fe5401d0499b30cf2f117515. The following
>> two patches fix that regression.
>
>
> Thanks! Do we need this in 2.10? If not pls ping after 2.10 is out.

I think it's not necessary since the regression appeared in 2.9
already, and it's a manual test.

I'll ping after 2.10

>
>> Thanks
>>
>> Marc-André Lureau (2):
>>   libvhost-user: support resuming vq->last_avail_idx based on used_idx
>>   vhost-user-bridge: fix resume regression (since 2.9)
>>
>>  contrib/libvhost-user/libvhost-user.h |  7 +++++++
>>  contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
>>  tests/vhost-user-bridge.c             |  7 +++++++
>>  3 files changed, 27 insertions(+)
>>
>> --
>> 2.14.1.146.gd35faa819
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [Qemu-stable] [PATCH v2 0/2] vhost-user-bridge reconnect regression

[Michael Roth]

Quoting Marc-André Lureau (2017-08-29 10:57:01)
> Hi
> 
> On Tue, Aug 29, 2017 at 5:34 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Tue, Aug 29, 2017 at 05:27:49PM +0200, Marc-André Lureau wrote:
> >> Hi,
> >>
> >> libvhost-user doesn't support resuming with the same trick vubr had
> >> since commit 523b018dde3b7650fe5401d0499b30cf2f117515. The following
> >> two patches fix that regression.
> >
> >
> > Thanks! Do we need this in 2.10? If not pls ping after 2.10 is out.
> 
> I think it's not necessary since the regression appeared in 2.9
> already, and it's a manual test.
> 
> I'll ping after 2.10

FYI I'm looking to get v2.10.1 out this month, freeze will likely be set for
Sep. 25th if you're looking to get this in.

> 
> >
> >> Thanks
> >>
> >> Marc-André Lureau (2):
> >>   libvhost-user: support resuming vq->last_avail_idx based on used_idx
> >>   vhost-user-bridge: fix resume regression (since 2.9)
> >>
> >>  contrib/libvhost-user/libvhost-user.h |  7 +++++++
> >>  contrib/libvhost-user/libvhost-user.c | 13 +++++++++++++
> >>  tests/vhost-user-bridge.c             |  7 +++++++
> >>  3 files changed, 27 insertions(+)
> >>
> >> --
> >> 2.14.1.146.gd35faa819
> >
> 
> 
> 
> -- 
> Marc-André Lureau
>