Re: [PATCH] virtio_pci: Wait for legacy device to be reset

From: Jason Wang
Date: Tue Apr 11 2023 - 01:25:09 EST


On Tue, Apr 11, 2023 at 9:39 AM Angus Chen <angus.chen@xxxxxxxxxxxxxxx> wrote:
>
> We read the status of device after reset,
> It is not guaranteed that the device be reseted successfully.
> We can use a while loop to make sure that,like the modern device did.
> The spec is not request it ,but it work.

The only concern is if it's too late to do this.

Btw, any reason you want to have a legacy hardware implementation. It
will be very tricky to work correctly.

Thanks

>
> Signed-off-by: Angus Chen <angus.chen@xxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_pci_legacy.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> index 2257f1b3d8ae..f2d241563e4f 100644
> --- a/drivers/virtio/virtio_pci_legacy.c
> +++ b/drivers/virtio/virtio_pci_legacy.c
> @@ -14,6 +14,7 @@
> * Michael S. Tsirkin <mst@xxxxxxxxxx>
> */
>
> +#include <linux/delay.h>
> #include "linux/virtio_pci_legacy.h"
> #include "virtio_pci_common.h"
>
> @@ -97,7 +98,8 @@ static void vp_reset(struct virtio_device *vdev)
> vp_legacy_set_status(&vp_dev->ldev, 0);
> /* Flush out the status write, and flush in device writes,
> * including MSi-X interrupts, if any. */
> - vp_legacy_get_status(&vp_dev->ldev);
> + while (vp_legacy_get_status(&vp_dev->ldev))
> + msleep(1);
> /* Flush pending VQ/configuration callbacks. */
> vp_synchronize_vectors(vdev);
> }
> --
> 2.25.1
>