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path: root/drivers/vhost
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2010-03-17vhost: fix error handling in vring ioctlsMichael S. Tsirkin
Stanse found a locking problem in vhost_set_vring: several returns from VHOST_SET_VRING_KICK, VHOST_SET_VRING_CALL, VHOST_SET_VRING_ERR with the vq->mutex held. Fix these up. Reported-by: Jiri Slaby <jirislaby@gmail.com> Acked-by: Laurent Chavey <chavey@google.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-17vhost: fix interrupt mitigation with raw socketsMichael S. Tsirkin
A thinko in code means we never trigger interrupt mitigation. Fix this. Reported-by: Juan Quintela <quintela@redhat.com> Reported-by: Unai Uribarri <unai.uribarri@optenet.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-07vhost: fix error path in vhost_net_set_backendJeff Dike
An error could cause vhost_net_set_backend to exit without unlocking vq->mutex. Fix this. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28vhost-net: restart tx poll on sk_sndbuf fullSridhar Samudrala
guest to remote communication with vhost net sometimes stops until guest driver is restarted. This happens when we get guest kick precisely when the backend send queue is full, as a result handle_tx() returns without polling backend. This patch fixes this by restarting tx poll on this condition. Signed-off-by: Sridhar Samudrala <samudrala@us.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Tested-by: Tom Lendacky <toml@us.ibm.com>
2010-02-28vhost: fix get_user_pages_fast error handlingMichael S. Tsirkin
get_user_pages_fast returns number of pages on success, negative value on failure, but never 0. Fix vhost code to match this logic. Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28vhost: initialize log eventfd context pointerMichael S. Tsirkin
vq log eventfd context pointer needs to be initialized, otherwise operation may fail or oops if log is enabled but log eventfd not set by userspace. When log_ctx for device is created, it is copied to the vq. This reset was missing. Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28vhost: logging thinko fixMichael S. Tsirkin
vhost was dong some complex math to get offset to log at, and got it wrong by a couple of bytes, while in fact it's simple: get address where we write, subtract start of buffer, add log base. Do it this way. Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-18net/macvtap: add vhost supportArnd Bergmann
This adds support for passing a macvtap file descriptor into vhost-net, much like we already do for tun/tap. Most of the new code is taken from the respective patch in the tun driver and may get consolidated in the future. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Sridhar Samudrala <sri@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-02-15vhost-net: switch to smp barriersMichael S. Tsirkin
vhost-net only uses memory barriers to control SMP effects (communication with userspace potentially running on a different CPU), so it should use SMP barriers and not mandatory barriers for memory access ordering, as suggested by Documentation/memory-barriers.txt Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-01-21vhost: fix TUN=m VHOST_NET=yMichael S. Tsirkin
drivers/built-in.o: In function `get_tun_socket': net.c:(.text+0x15436e): undefined reference to `tun_get_socket' If tun is a module, vhost must be a module, too. If tun is built-in or disabled, vhost can be built-in. Note: TUN || !TUN might look a bit strange until you realize that boolean logic rules do not apply for tristate variables. Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-01-15vhost_net: a kernel-level virtio serverMichael S. Tsirkin
What it is: vhost net is a character device that can be used to reduce the number of system calls involved in virtio networking. Existing virtio net code is used in the guest without modification. There's similarity with vringfd, with some differences and reduced scope - uses eventfd for signalling - structures can be moved around in memory at any time (good for migration, bug work-arounds in userspace) - write logging is supported (good for migration) - support memory table and not just an offset (needed for kvm) common virtio related code has been put in a separate file vhost.c and can be made into a separate module if/when more backends appear. I used Rusty's lguest.c as the source for developing this part : this supplied me with witty comments I wouldn't be able to write myself. What it is not: vhost net is not a bus, and not a generic new system call. No assumptions are made on how guest performs hypercalls. Userspace hypervisors are supported as well as kvm. How it works: Basically, we connect virtio frontend (configured by userspace) to a backend. The backend could be a network device, or a tap device. Backend is also configured by userspace, including vlan/mac etc. Status: This works for me, and I haven't see any crashes. Compared to userspace, people reported improved latency (as I save up to 4 system calls per packet), as well as better bandwidth and CPU utilization. Features that I plan to look at in the future: - mergeable buffers - zero copy - scalability tuning: figure out the best threading model to use Note on RCU usage (this is also documented in vhost.h, near private_pointer which is the value protected by this variant of RCU): what is happening is that the rcu_dereference() is being used in a workqueue item. The role of rcu_read_lock() is taken on by the start of execution of the workqueue item, of rcu_read_unlock() by the end of execution of the workqueue item, and of synchronize_rcu() by flush_workqueue()/flush_work(). In the future we might need to apply some gcc attribute or sparse annotation to the function passed to INIT_WORK(). Paul's ack below is for this RCU usage. (Includes fixes by Alan Cox <alan@linux.intel.com>, David L Stevens <dlstevens@us.ibm.com>, Chris Wright <chrisw@redhat.com>) Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>