linux-kernel - [PATCH pre-squash 12/14] virtio_pci: add module param to force legacy mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1421852375-22604-13-git-send-email-mst@redhat.com>
Date:	Wed, 21 Jan 2015 17:00:42 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	virtualization@...ts.linux-foundation.org,
	Gerd Hoffmann <kraxel@...hat.com>
Subject: [PATCH pre-squash 12/14] 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@...hat.com>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Tested-by: Gerd Hoffmann <kraxel@...hat.com>
---
 drivers/virtio/virtio_pci_common.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 8ae34a3..0f87b99 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 +513,24 @@ 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)
+			return rc;
+
+		rc = virtio_pci_modern_probe(vp_dev);
+		if (rc)
+			goto err_probe;
+	} else {
+		rc = virtio_pci_modern_probe(vp_dev);
+		if (rc != -ENODEV)
+			return rc;
+
+		rc = virtio_pci_legacy_probe(vp_dev);
+		if (rc)
+			goto err_probe;
+	}
 
 	pci_set_master(pci_dev);
 
-- 
MST

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/