[UNIKRAFT PATCH RFCv4 35/35] plat/virtio: Fix the return value check for virtio_cread_bytes_many()

[Jia He <justin.he@xxxxxxx>]

The return value of virtio_cread_bytes_many can be:
1) is -1 if something wrong
2) is len (>=0) if everything is fine

So the check condition in vpci_legacy_pci_config_get should be adjusted
if rc!=len

Otherwise, the initialization of virtio-9p device will be failed on
arm64 kvm plat.

Signed-off-by: Jia He <justin.he@xxxxxxx>
---
 plat/drivers/virtio/virtio_pci.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/plat/drivers/virtio/virtio_pci.c b/plat/drivers/virtio/virtio_pci.c
index 3c62a3c..3a2229a 100644
--- a/plat/drivers/virtio/virtio_pci.c
+++ b/plat/drivers/virtio/virtio_pci.c
@@ -278,8 +278,11 @@ static int vpci_legacy_pci_config_get(struct virtio_dev 
*vdev, __u16 offset,
                rc = virtio_cread_bytes_many(
                                (void *) (unsigned long)vpdev->pci_base_addr,
                                VIRTIO_PCI_CONFIG_OFF + offset, buf, len);
+               if (rc != (int)len)
+                       return -EFAULT;
        }
-       return rc;
+
+       return 0;
 }
 
 static __u8 vpci_legacy_pci_status_get(struct virtio_dev *vdev)
-- 
2.17.1