litmus2008.git/drivers/virtio, branch master

virtio: fix module/device unloading

2007-11-19T00:20:42+00:00

The virtio code never hooked through the ->remove callback.  Although
noone supports device removal at the moment, this code is already
needed for module unloading.

This of course also revealed bugs in virtio_blk, virtio_net and lguest
unloading paths.

Signed-off-by: Rusty Russell

virtio: Force use of power-of-two for descriptor ring sizes

2007-11-12T02:59:40+00:00

The virtio descriptor rings of size N-1 were nicely set up to be
aligned to an N-byte boundary.  But as Anthony Liguori points out, the
free-running indices used by virtio require that the sizes be a power
of 2, otherwise we get problems on wrap (demonstrated with lguest).

So we replace the clever "2^n-1" scheme with a simple "align to page
boundary" scheme: this means that all virtio rings take at least two
pages, but it's safer than guessing cache alignment.

Signed-off-by: Rusty Russell

virtio: Fix used_idx wrap-around

2007-11-12T02:59:09+00:00

The more_used() function compares the vq->vring.used->idx with last_used_idx.
Since vq->vring.used->idx is a 16-bit integer, and last_used_idx is an
unsigned int, this results in unpredictable behavior when vq->vring.used->idx
wraps around.

This patch corrects this by changing last_used_idx to the correct type.

Signed-off-by: Anthony Liguori 
Signed-off-by: Rusty Russell

Virtio helper routines for a descriptor ringbuffer implementation

2007-10-23T05:49:55+00:00

These helper routines supply most of the virtqueue_ops for hypervisors
which want to use a ring for virtio.  Unlike the previous lguest
implementation:

1) The rings are variable sized (2^n-1 elements).
2) They have an unfortunate limit of 65535 bytes per sg element.
3) The page numbers are always 64 bit (PAE anyone?)
4) They no longer place used[] on a separate page, just a separate
   cacheline.
5) We do a modulo on a variable.  We could be tricky if we cared.
6) Interrupts and notifies are suppressed using flags within the rings.

Users need only get the ring pages and provide a notify hook (KVM
wants the guest to allocate the rings, lguest does it sanely).

Signed-off-by: Rusty Russell 
Cc: Dor Laor

Module autoprobing support for virtio drivers.

2007-10-23T05:49:55+00:00

This adds the logic to convert the virtio ids into module aliases, and
includes a modalias entry in sysfs and the env var to make probing work.

Signed-off-by: Rusty Russell

Virtio interface

2007-10-23T05:49:54+00:00

This attempts to implement a "virtual I/O" layer which should allow
common drivers to be efficiently used across most virtual I/O
mechanisms.  It will no-doubt need further enhancement.

The virtio drivers add buffers to virtio queues; as the buffers are consumed
the driver "interrupt" callbacks are invoked.

There is also a generic implementation of config space which drivers can query
to get setup information from the host.

Signed-off-by: Rusty Russell 
Cc: Dor Laor 
Cc: Arnd Bergmann