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authorMichael S. Tsirkin <mst@redhat.com>2015-01-15 17:54:13 +0200
committerRusty Russell <rusty@rustcorp.com.au>2015-01-21 16:29:01 +1030
commitac399d8f39a860655961660efa5c67e7f3c47912 (patch)
tree564273dc5bd0732dfe868860060df59c23860468 /drivers/virtio
parent46506da5f365efe7fe3e4c9da73ab679c0382fac (diff)
downloadlinux-ac399d8f39a860655961660efa5c67e7f3c47912.tar.bz2
virtio_pci: add module param to force legacy mode
If set, try legacy interface first, modern one if that fails. Useful to work around device/driver bugs, and for compatibility testing. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_pci_common.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 8ae34a34f3af..e894eb278d83 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -19,6 +19,14 @@
#include "virtio_pci_common.h"
+static bool force_legacy = false;
+
+#if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
+module_param(force_legacy, bool, 0444);
+MODULE_PARM_DESC(force_legacy,
+ "Force legacy mode for transitional virtio 1 devices");
+#endif
+
/* wait for pending irq handlers */
void vp_synchronize_vectors(struct virtio_device *vdev)
{
@@ -505,11 +513,20 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
if (rc)
goto err_request_regions;
- rc = virtio_pci_modern_probe(vp_dev);
- if (rc == -ENODEV)
+ if (force_legacy) {
rc = virtio_pci_legacy_probe(vp_dev);
- if (rc)
- goto err_probe;
+ /* Also try modern mode if we can't map BAR0 (no IO space). */
+ if (rc == -ENODEV || rc == -ENOMEM)
+ rc = virtio_pci_modern_probe(vp_dev);
+ if (rc)
+ goto err_probe;
+ } else {
+ rc = virtio_pci_modern_probe(vp_dev);
+ if (rc == -ENODEV)
+ rc = virtio_pci_legacy_probe(vp_dev);
+ if (rc)
+ goto err_probe;
+ }
pci_set_master(pci_dev);