linux-kernel - [PATCH] virtio_pci: Wait for legacy device to be reset

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Date:   Tue, 11 Apr 2023 09:38:32 +0800
From:   Angus Chen <angus.chen@...uarmicro.com>
To:     mst@...hat.com, jasowang@...hat.com
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Angus Chen <angus.chen@...uarmicro.com>
Subject: [PATCH] virtio_pci: Wait for legacy device to be reset

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.

Signed-off-by: Angus Chen <angus.chen@...uarmicro.com>
---
 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@...hat.com>
  */
 
+#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