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author | Rusty Russell <rusty@rustcorp.com.au> | 2008-02-05 07:50:03 +0300 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-02-04 15:50:03 +0300 |
commit | 6e5aa7efb27aec7e55b6463fa2c8db594c4226fa (patch) | |
tree | 060a955e711ac224136157a5410e88dcdab965af /drivers/lguest/lguest_device.c | |
parent | b3369c1fb410fddeb38a404316c861395f6d6ae8 (diff) | |
download | linux-6e5aa7efb27aec7e55b6463fa2c8db594c4226fa.tar.xz |
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>
Diffstat (limited to 'drivers/lguest/lguest_device.c')
-rw-r--r-- | drivers/lguest/lguest_device.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c index ced5b44cebce..84f85e23cca7 100644 --- a/drivers/lguest/lguest_device.c +++ b/drivers/lguest/lguest_device.c @@ -54,7 +54,7 @@ struct lguest_device { * * The configuration information for a device consists of one or more * virtqueues, a feature bitmaks, and some configuration bytes. The - * configuration bytes don't really matter to us: the Launcher set them up, and + * configuration bytes don't really matter to us: the Launcher sets them up, and * the driver will look at them during setup. * * A convenient routine to return the device's virtqueue config array: @@ -139,9 +139,20 @@ static u8 lg_get_status(struct virtio_device *vdev) static void lg_set_status(struct virtio_device *vdev, u8 status) { + BUG_ON(!status); to_lgdev(vdev)->desc->status = status; } +/* To reset the device, we (ab)use the NOTIFY hypercall, with the descriptor + * address of the device. The Host will zero the status and all the + * features. */ +static void lg_reset(struct virtio_device *vdev) +{ + unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices; + + hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0); +} + /* * Virtqueues * @@ -279,6 +290,7 @@ static struct virtio_config_ops lguest_config_ops = { .set = lg_set, .get_status = lg_get_status, .set_status = lg_set_status, + .reset = lg_reset, .find_vq = lg_find_vq, .del_vq = lg_del_vq, }; |