linux.git/drivers/virtio/virtio_ring.c, branch v3.10

virtio_ring: virtqueue_add_outbuf / virtqueue_add_inbuf.

2013-03-20T05:14:52+00:00

These are specialized versions of virtqueue_add_buf(), which cover
over 80% of cases and are far clearer.

In particular, the scatterlists passed to these functions don't have
to be clean (ie. we ignore end markers).

Signed-off-by: Rusty Russell

virtio_ring: virtqueue_add_sgs, to add multiple sgs.

2013-03-20T05:13:29+00:00

virtio_scsi can really use this, to avoid the current hack of copying
the whole sg array.  Some other things get slightly neater, too.

This causes a slowdown in virtqueue_add_buf(), which is implemented as
a wrapper.  This is addressed in the next patches.

for i in `seq 50`; do /usr/bin/time -f 'Wall time:%e' ./vringh_test --indirect --eventidx --parallel --fast-vringh; done 2>&1 | stats --trim-outliers:

Before:
	Using CPUS 0 and 3
	Guest: notified 0, pinged 39009-39063(39062)
	Host: notified 39009-39063(39062), pinged 0
	Wall time:1.700000-1.950000(1.723542)

After:
	Using CPUS 0 and 3
	Guest: notified 0, pinged 39062-39063(39063)
	Host: notified 39062-39063(39063), pinged 0
	Wall time:1.760000-2.220000(1.789167)

Signed-off-by: Rusty Russell 
Reviewed-by: Wanlong Gao 
Reviewed-by: Asias He

virtio_ring: expose virtio barriers for use in vringh.

2013-03-20T03:30:41+00:00

The host side of ring needs this logic too.

Signed-off-by: Rusty Russell

virtio: make virtqueue_add_buf() returning 0 on success, not capacity.

2012-12-18T04:50:34+00:00

Now noone relies on this behavior, we simplify virtqueue_add_buf() so it
return 0 or -errno.

Signed-off-by: Rusty Russell 
Acked-by: Michael S. Tsirkin

virtio: move queue_index and num_free fields into core struct virtqueue.

2012-12-18T04:50:31+00:00

They're generic concepts, so hoist them.  This also avoids accessor
functions (though kept around for merge with DaveM's net tree).

This goes even further than Jason Wang's 17bb6d4088 patch
("virtio-ring: move queue_index to vring_virtqueue") which moved the
queue_index from the specific transport.

Acked-by: Michael S. Tsirkin 
Signed-off-by: Rusty Russell

virtio: force vring descriptors to be allocated from lowmem

2012-10-22T07:49:49+00:00

Virtio devices may attempt to add descriptors to a virtqueue from atomic
context using GFP_ATOMIC allocation. This is problematic because such
allocations can fall outside of the lowmem mapping, causing virt_to_phys
to report bogus physical addresses which are subsequently passed to
userspace via the buffers for the virtual device.

This patch masks out __GFP_HIGH and __GFP_HIGHMEM from the requested
flags when allocating descriptors for a virtqueue. If an atomic
allocation is requested and later fails, we will return -ENOSPC which
will be handled by the driver.

Cc: stable@kernel.org
Cc: Sasha Levin 
Signed-off-by: Will Deacon 
Signed-off-by: Rusty Russell

virtio-ring: move queue_index to vring_virtqueue

2012-09-28T05:35:15+00:00

Instead of storing the queue index in transport-specific virtio structs,
this patch moves them to vring_virtqueue and introduces an helper to get
the value.  This lets drivers simplify their management and tracing of
virtqueues.

Signed-off-by: Jason Wang 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Rusty Russell

virtio: correct the memory barrier in virtqueue_kick_prepare()

2012-01-27T21:40:23+00:00

Use virtio_mb() to make sure the available index to be exposed before
checking the the avail event. Otherwise we may get stale value of
avail event in guest and never kick the host after.

Note: this fixes a bug introduced by ee7cd8981e15bcb365fc762afe3fc47b8242f630.

Signed-off-by: Jason Wang 
Acked-by: Michael S. Tsirkin 
Signed-off-by: Rusty Russell 
Cc: stable@kernel.org

virtio: fix typos of memory barriers

2012-01-27T21:40:22+00:00

Note: this fixes a bug introduced recently in
7b21e34fd1c272e3a8c3846168f2f6287a4cd72b.

Signed-off-by: Jason Wang 
Acked-by: Michael S. Tsirkin 
Signed-off-by: Rusty Russell

virtio: add debugging if driver doesn't kick.

2012-01-12T05:14:43+00:00

Under the existing #ifdef DEBUG, check that they don't have more than
1/10 of a second between an add_buf() and a
virtqueue_notify()/virtqueue_kick_prepare() call.

We could get false positives on a really busy system, but good for
development.

Signed-off-by: Rusty Russell