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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com,
	jianfeng.tan@intel.com
Cc: lprosek@redhat.com, lersek@redhat.com,
	Maxime Coquelin <maxime.coquelin@redhat.com>
Subject: [dpdk-dev] [PATCH 1/4] vhost: prevent features to be changed while device is running
Date: Mon,  4 Dec 2017 15:08:57 +0100	[thread overview]
Message-ID: <20171204140900.7906-2-maxime.coquelin@redhat.com> (raw)
In-Reply-To: <20171204140900.7906-1-maxime.coquelin@redhat.com>

As section 2.2 of the Virtio spec states about features
negotiation:
"During device initialization, the driver reads this and tells
the device the subset that it accepts. The only way to
renegotiate is to reset the device."

This patch implements a check to prevent illegal features change
while the device is running.

One exception is the VHOST_F_LOG_ALL feature bit, which is enabled
when live-migration is initiated. But this feature is not negotiated
with the Virtio driver, but directly with the Vhost master.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index f4c7ce462..f51055ab2 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -183,7 +183,22 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
 		return -1;
 	}
 
-	if ((dev->flags & VIRTIO_DEV_RUNNING) && dev->features != features) {
+	if (dev->features == features)
+		return 0;
+
+	if (dev->flags & VIRTIO_DEV_RUNNING) {
+		/*
+		 * Error out if master tries to change features while device is
+		 * in running state. The exception being VHOST_F_LOG_ALL, which
+		 * is enabled when the live-migration starts.
+		 */
+		if ((dev->features ^ features) & ~(1ULL >> VHOST_F_LOG_ALL)) {
+			RTE_LOG(ERR, VHOST_CONFIG,
+				"(%d) features changed while device is running.\n",
+				dev->vid);
+			return -1;
+		}
+
 		if (dev->notify_ops->features_changed)
 			dev->notify_ops->features_changed(dev->vid, features);
 	}
-- 
2.14.3

  reply	other threads:[~2017-12-04 14:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-04 14:08 [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ not negotiated Maxime Coquelin
2017-12-04 14:08 ` Maxime Coquelin [this message]
2017-12-04 14:17   ` [dpdk-dev] [PATCH 1/4] vhost: prevent features to be changed while device is running Ladi Prosek
2017-12-04 14:20     ` Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 2/4] vhost: propagate VHOST_USER_SET_FEATURES handling error Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 3/4] vhost: extract virtqueue cleaning and freeing functions Maxime Coquelin
2017-12-04 14:09 ` [dpdk-dev] [PATCH 4/4] vhost: destroy unused virtqueues when multiqueue not negotiated Maxime Coquelin
2017-12-04 14:27 ` [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Ladi Prosek
2017-12-04 14:48   ` Maxime Coquelin

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