Commit Graph

7 Commits

Author SHA1 Message Date
Rusty Russell
6e5aa7efb2 virtio: reset function
A reset function solves three problems:

1) It allows us to renegotiate features, eg. if we want to upgrade a
   guest driver without rebooting the guest.

2) It gives us a clean way of shutting down virtqueues: after a reset,
   we know that the buffers won't be used by the host, and

3) It helps the guest recover from messed-up drivers.

So we remove the ->shutdown hook, and the only way we now remove
feature bits is via reset.

We leave it to the driver to do the reset before it deletes queues:
the balloon driver, for example, needs to chat to the host in its
remove function.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:03 +11:00
Rusty Russell
18445c4d50 virtio: explicit enable_cb/disable_cb rather than callback return.
It seems that virtio_net wants to disable callbacks (interrupts) before
calling netif_rx_schedule(), so we can't use the return value to do so.

Rename "restart" to "cb_enable" and introduce "cb_disable" hook: callback
now returns void, rather than a boolean.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:49:58 +11:00
Rusty Russell
a586d4f601 virtio: simplify config mechanism.
Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:49:57 +11:00
Rusty Russell
74b2553f1d virtio: fix module/device unloading
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 <rusty@rustcorp.com.au>
2007-11-19 11:20:42 +11:00
Rusty Russell
42b36cc0ce virtio: Force use of power-of-two for descriptor ring sizes
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 <rusty@rustcorp.com.au>
2007-11-12 13:59:40 +11:00
Rusty Russell
e1e72965ec lguest: documentation update
Went through the documentation doing typo and content fixes.  This
patch contains only comment and whitespace changes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-25 15:02:50 +10:00
Rusty Russell
19f1537b7b Lguest support for Virtio
This makes lguest able to use the virtio devices.

We change the device descriptor page from a simple array to a variable
length "type, config_len, status, config data..." format, and
implement virtio_config_ops to read from that config data.

We use the virtio ring implementation for an efficient Guest <-> Host
virtqueue mechanism, and the new LHCALL_NOTIFY hypercall to kick the
host when it changes.

We also use LHCALL_NOTIFY on kernel addresses for very very early
console output.  We could have another hypercall, but this hack works
quite well.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:56 +10:00