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virtio: virtio 1.0 cs04 spec compliance for reset

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commit 05dbcb430795b2e1fb1d5c757f8619d3dbed0a1c upstream.

The spec says: after writing 0 to device_status, the driver MUST wait
for a read of device_status to return 0 before reinitializing the
device.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael S. Tsirkin 2016-04-03 15:23:37 +03:00 committed by Greg Kroah-Hartman
parent 06e2d7dd90
commit 5f6e35c2f9
1 changed files with 8 additions and 3 deletions
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11
drivers/virtio/virtio_pci_modern.c
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@ -17,6 +17,7 @@
*
*/
#include <linux/delay.h>
#define VIRTIO_PCI_NO_LEGACY
#include "virtio_pci_common.h"
@ -271,9 +272,13 @@ static void vp_reset(struct virtio_device *vdev)
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
/* 0 status means a reset. */
vp_iowrite8(0, &vp_dev->common->device_status);
/* Flush out the status write, and flush in device writes,
* including MSI-X interrupts, if any. */
vp_ioread8(&vp_dev->common->device_status);
/* After writing 0 to device_status, the driver MUST wait for a read of
* device_status to return 0 before reinitializing the device.
* This will flush out the status write, and flush in device writes,
* including MSI-X interrupts, if any.
*/
while (vp_ioread8(&vp_dev->common->device_status))
msleep(1);
/* Flush pending VQ/configuration callbacks. */
vp_synchronize_vectors(vdev);
}