[PATCH v2 0/1] virtio_bt: Fix alignment in configuration struct

[PATCH v2 0/1] virtio_bt: Fix alignment in configuration struct

[Igor Skalkin]

According to specification [1], "For the device-specific configuration
space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
and aligned accesses for 32 and 64 bit wide fields.".

Current version of the configuration structure has non-aligned 16bit
fields.

This patch adds a second, aligned  version of the configuration structure
and a new feature bit indicating that this version is being used.

[1] https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf

Changes in v2:
  The first version of this patch just changed the configuration
  structure in uapi/linux/virtio_bt.h
  This can not be done, because it will break the userspace, so the
  second version offers a less radical approach - it introduces a new
  feature bit and a new configuration structure that both the device
  and the driver will use if this bit is negotiated.

Igor Skalkin (1):
  virtio_bt: Fix alignment in configuration struct

 drivers/bluetooth/virtio_bt.c  | 16 +++++++++++++---
 include/uapi/linux/virtio_bt.h |  8 ++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

-- 
2.37.2

[PATCH v2 1/1] virtio_bt: Fix alignment in configuration struct

[Igor Skalkin]

The current version of the configuration structure has unaligned
16-bit fields, but according to the specification [1], access to
the configuration space must be aligned.

Add a second, aligned  version of the configuration structure
and a new feature bit indicating that this version is being used.

[1] https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf

Signed-off-by: Igor Skalkin <Igor.Skalkin@opensynergy.com>
---
 drivers/bluetooth/virtio_bt.c  | 16 +++++++++++++---
 include/uapi/linux/virtio_bt.h |  8 ++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 67c21263f9e0..35f8041722c8 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -306,7 +306,12 @@ static int virtbt_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_BT_F_VND_HCI)) {
 		__u16 vendor;
 
-		virtio_cread(vdev, struct virtio_bt_config, vendor, &vendor);
+		if (virtio_has_feature(vdev, VIRTIO_BT_F_CONFIG_V2))
+			virtio_cread(vdev, struct virtio_bt_config_v2,
+				     vendor, &vendor);
+		else
+			virtio_cread(vdev, struct virtio_bt_config,
+				     vendor, &vendor);
 
 		switch (vendor) {
 		case VIRTIO_BT_CONFIG_VENDOR_ZEPHYR:
@@ -339,8 +344,12 @@ static int virtbt_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_BT_F_MSFT_EXT)) {
 		__u16 msft_opcode;
 
-		virtio_cread(vdev, struct virtio_bt_config,
-			     msft_opcode, &msft_opcode);
+		if (virtio_has_feature(vdev, VIRTIO_BT_F_CONFIG_V2))
+			virtio_cread(vdev, struct virtio_bt_config_v2,
+				     msft_opcode, &msft_opcode);
+		else
+			virtio_cread(vdev, struct virtio_bt_config,
+				     msft_opcode, &msft_opcode);
 
 		hci_set_msft_opcode(hdev, msft_opcode);
 	}
@@ -387,6 +396,7 @@ static const unsigned int virtbt_features[] = {
 	VIRTIO_BT_F_VND_HCI,
 	VIRTIO_BT_F_MSFT_EXT,
 	VIRTIO_BT_F_AOSP_EXT,
+	VIRTIO_BT_F_CONFIG_V2,
 };
 
 static struct virtio_driver virtbt_driver = {
diff --git a/include/uapi/linux/virtio_bt.h b/include/uapi/linux/virtio_bt.h
index a7bd48daa9a9..af798f4c9680 100644
--- a/include/uapi/linux/virtio_bt.h
+++ b/include/uapi/linux/virtio_bt.h
@@ -9,6 +9,7 @@
 #define VIRTIO_BT_F_VND_HCI	0	/* Indicates vendor command support */
 #define VIRTIO_BT_F_MSFT_EXT	1	/* Indicates MSFT vendor support */
 #define VIRTIO_BT_F_AOSP_EXT	2	/* Indicates AOSP vendor support */
+#define VIRTIO_BT_F_CONFIG_V2	3	/* Use second version configuration */
 
 enum virtio_bt_config_type {
 	VIRTIO_BT_CONFIG_TYPE_PRIMARY	= 0,
@@ -28,4 +29,11 @@ struct virtio_bt_config {
 	__u16 msft_opcode;
 } __attribute__((packed));
 
+struct virtio_bt_config_v2 {
+	__u8  type;
+	__u8  alignment;
+	__u16 vendor;
+	__u16 msft_opcode;
+};
+
 #endif /* _UAPI_LINUX_VIRTIO_BT_H */
-- 
2.37.2

Re: [PATCH v2 0/1] virtio_bt: Fix alignment in configuration struct

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Tue, 18 Oct 2022 19:30:49 +0200 you wrote:
> According to specification [1], "For the device-specific configuration
> space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
> 16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
> and aligned accesses for 32 and 64 bit wide fields.".
> 
> Current version of the configuration structure has non-aligned 16bit
> fields.
> 
> [...]

Here is the summary with links:
  - [v2,1/1] virtio_bt: Fix alignment in configuration struct
    https://git.kernel.org/bluetooth/bluetooth-next/c/57dc0d471d27

You are awesome, thank you!
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