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authorRusty Russell <rusty@rustcorp.com.au>2011-07-22 09:09:49 +0400
committerRusty Russell <rusty@rustcorp.com.au>2011-07-22 09:09:49 +0400
commit3c3ed482dc077a67903a58c9e1aedba1bb18c18a (patch)
treead3987515d68fcfa7155574e53ab47aabd41e593 /drivers/lguest/lguest_device.c
parent6d7a5d1ea34495ecb1d608f0e40afba7776ee408 (diff)
downloadlinux-3c3ed482dc077a67903a58c9e1aedba1bb18c18a.tar.xz
lguest: Simplify device initialization.
We used to notify the Host every time we updated a device's status. However, it only really needs to know when we're resetting the device, or failed to initialize it, or when we've finished our feature negotiation. In particular, we used to wait for VIRTIO_CONFIG_S_DRIVER_OK in the status byte before starting the device service threads. But this corresponds to the successful finish of device initialization, which might (like virtio_blk's partition scanning) use the device. So we had a hack, if they used the device before we expected we started the threads anyway. Now we hook into the finalize_features hook in the Guest: at that point we tell the Launcher that it can rely on the features we have acked. On the Launcher side, we look at the status at that point, and start servicing the device. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/lguest/lguest_device.c')
-rw-r--r--drivers/lguest/lguest_device.c37
1 files changed, 22 insertions, 15 deletions
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 69c84a1d88ea..5289ffa2e500 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -109,6 +109,17 @@ static u32 lg_get_features(struct virtio_device *vdev)
}
/*
+ * To notify on reset or feature finalization, we (ab)use the NOTIFY
+ * hypercall, with the descriptor address of the device.
+ */
+static void status_notify(struct virtio_device *vdev)
+{
+ unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+ hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
+}
+
+/*
* The virtio core takes the features the Host offers, and copies the ones
* supported by the driver into the vdev->features array. Once that's all
* sorted out, this routine is called so we can tell the Host which features we
@@ -135,6 +146,9 @@ static void lg_finalize_features(struct virtio_device *vdev)
if (test_bit(i, vdev->features))
out_features[i / 8] |= (1 << (i % 8));
}
+
+ /* Tell Host we've finished with this device's feature negotiation */
+ status_notify(vdev);
}
/* Once they've found a field, getting a copy of it is easy. */
@@ -168,28 +182,21 @@ static u8 lg_get_status(struct virtio_device *vdev)
return to_lgdev(vdev)->desc->status;
}
-/*
- * To notify on status updates, we (ab)use the NOTIFY hypercall, with the
- * descriptor address of the device. A zero status means "reset".
- */
-static void set_status(struct virtio_device *vdev, u8 status)
-{
- unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
-
- /* We set the status. */
- to_lgdev(vdev)->desc->status = status;
- hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
-}
-
static void lg_set_status(struct virtio_device *vdev, u8 status)
{
BUG_ON(!status);
- set_status(vdev, status);
+ to_lgdev(vdev)->desc->status = status;
+
+ /* Tell Host immediately if we failed. */
+ if (status & VIRTIO_CONFIG_S_FAILED)
+ status_notify(vdev);
}
static void lg_reset(struct virtio_device *vdev)
{
- set_status(vdev, 0);
+ /* 0 status means "reset" */
+ to_lgdev(vdev)->desc->status = 0;
+ status_notify(vdev);
}
/*