On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
From: Longpeng <longpeng2@xxxxxxxxxx>
1. We should not set status to 0 when invoking vp_vdpa_set_status().
2. The driver MUST wait for a read of device_status to return 0 before
reinitializing the device.
Signed-off-by: Longpeng <longpeng2@xxxxxxxxxx>
---
drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
index d448db0c4de3..d35fac5cde11 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
@@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
{
struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
- u8 s = vp_vdpa_get_status(vdpa);
Is this change really needed?
+ u8 s;
+
+ /* We should never be setting status to 0. */
+ BUG_ON(status == 0);
IMHO panicking the kernel seems excessive in this case, please use
WARN_ON and maybe return earlier.
+ s = vp_vdpa_get_status(vdpa);
if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
!(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
vp_vdpa_request_irq(vp_vdpa);
@@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
u8 s = vp_vdpa_get_status(vdpa);
vp_modern_set_status(mdev, 0);
+ /* After writing 0 to device_status, the driver MUST wait for a read of
+ * device_status to return 0 before reinitializing the device.
+ */
+ while (vp_modern_get_status(mdev))
+ msleep(1);
Should we set a limit after which we give up? A malfunctioning device
could keep us here forever.
Thanks,
Stefano
if (s & VIRTIO_CONFIG_S_DRIVER_OK)
vp_vdpa_free_irq(vp_vdpa);
--
2.23.0
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