linux.git/drivers/virtio/virtio.c, branch v2.6.30

virtio: struct device - replace bus_id with dev_name(), dev_set_name()

2008-12-29T22:55:56+00:00

This patch is part of a larger patch series which will remove
the "char bus_id[20]" name string from struct device. The device
name is managed in the kobject anyway, and without any size
limitation, and just needlessly copied into "struct device".

To set and read the device name dev_name(dev) and dev_set_name(dev)
must be used. If your code uses static kobjects, which it shouldn't
do, "const char *init_name" can be used to statically provide the
name the registered device should have. At registration time, the
init_name field is cleared, to enforce the use of dev_name(dev) to
access the device name at a later time.

We need to get rid of all occurrences of bus_id in the entire tree
to be able to enable the new interface. Please apply this patch,
and possibly convert any remaining remaining occurrences of bus_id.

We want to submit a patch to -next, which will remove bus_id from
"struct device", to find the remaining pieces to convert, and finally
switch over to the new api, which will remove the 20 bytes array
and does no longer have a size limitation.

Acked-by: Greg Kroah-Hartman 
Signed-off-by: Kay Sievers 
Signed-off-by: Rusty Russell

virtio: Rename set_features to finalize_features

2008-07-25T02:06:12+00:00

Rather than explicitly handing the features to the lower-level, we just
hand the virtio_device and have it set the features.  This make it clear
that it has the chance to manipulate the features of the device at this
point (and that all feature negotiation is already done).

Signed-off-by: Rusty Russell

virtio: Formally reserve bits 28-31 to be 'transport' features.

2008-07-25T02:06:07+00:00

We assign feature bits as required, but it makes sense to reserve some
for the particular transport, rather than the particular device.

Signed-off-by: Rusty Russell

virtio: Use bus_type probe and remove methods

2008-07-25T02:06:05+00:00

Hook up to the probe() and remove() methods in bus_type
rather than device_driver. The latter has been preferred
since 2.6.16.

Signed-off-by: Mark McLoughlin 
Signed-off-by: Rusty Russell

virtio: Complete feature negotation before updating status

2008-06-15T20:46:16+00:00

lguest (in rusty's use-tun-ringfd patch) assumes that the
guest has updated its feature bits before setting its status
to VIRTIO_CONFIG_S_DRIVER_OK.

That's pretty reasonable, so let's make it so.

Signed-off-by: Mark McLoughlin 
Signed-off-by: Rusty Russell 
Signed-off-by: Linus Torvalds

virtio: set device index in common code.

2008-05-30T05:09:42+00:00

Anthony Liguori points out that three different transports use the virtio code,
but each one keeps its own counter to set the virtio_device's index field.  In
theory (though not in current practice) this means that names could be
duplicated, and that risk grows as more transports are created.

So we move the selection of the unique virtio_device.index into the common code
in virtio.c, which has the side-benefit of removing duplicate code.

The only complexity is that lguest and S/390 use the index to uniquely identify
the device in case of catastrophic failure before register_virtio_device() is
called: now we use the offset within the descriptor page as a unique identifier
for the printks.

Signed-off-by: Rusty Russell 
Cc: Christian Borntraeger 
Cc: Martin Schwidefsky 
Cc: Carsten Otte 
Cc: Heiko Carstens 
Cc: Chris Lalancette 
Cc: Anthony Liguori

virtio: bus_id for devices should contain 'virtio'

2008-05-30T05:09:42+00:00

Chris Lalancette  points out that virtio.c sets all device
names to '0', '1', etc, which looks silly in /proc/interrupts.  We change this
from '%d' to 'virtio%d'.

Signed-off-by: Rusty Russell 
Cc: Christian Borntraeger 
Cc: Martin Schwidefsky 
Cc: Carsten Otte 
Cc: Heiko Carstens 
Cc: Chris Lalancette 
Cc: Anthony Liguori

virtio: explicit advertisement of driver features

2008-05-02T11:50:50+00:00

A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.

There is nothing in the API to require this, however, and even I
didn't notice when it was violated.

So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core.  The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.

Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.

Drivers can still remove feature bits in their probe routine if they
really have to.

API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits

Signed-off-by: Rusty Russell

virtio: Allow virtio to be modular and used by modules

2008-02-04T12:50:06+00:00

This is needed for the virtio PCI device to be compiled as a module.

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

virtio: reset function

2008-02-04T12:50:03+00:00

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