Re: [PATCH v2 2/2] Bluetooth: btusb: Read the supported features of Microsoft vendor extension

From: Marcel Holtmann
Date: Wed Mar 25 2020 - 04:25:17 EST


Hi Miao-chen,

> This adds a new header to facilitate the opcode and packet structures of
> vendor extension(s). For now, we add only the
> HCI_VS_MSFT_Read_Supported_Features command from Microsoft vendor
> extension. See https://docs.microsoft.com/en-us/windows-hardware/drivers/
> bluetooth/microsoft-defined-bluetooth-hci-commands-and-events#
> microsoft-defined-bluetooth-hci-events for more details.
> Upon initialization of a hci_dev, we issue a
> HCI_VS_MSFT_Read_Supported_Features command to read the supported features
> of Microsoft vendor extension if the opcode of Microsoft vendor extension
> is valid. See https://docs.microsoft.com/en-us/windows-hardware/drivers/
> bluetooth/microsoft-defined-bluetooth-hci-commands-and-events#
> hci_vs_msft_read_supported_features for more details.
> This was verified on a device with Intel ThhunderPeak BT controller where
> the Microsoft vendor extension features are 0x000000000000003f.
>
> Signed-off-by: Miao-chen Chou <mcchou@xxxxxxxxxxxx>
> ---
>
> Changes in v2:
> - Issue a HCI_VS_MSFT_Read_Supported_Features command with
> __hci_cmd_sync() instead of constructing a request.
>
> drivers/bluetooth/btusb.c | 3 ++
> include/net/bluetooth/hci_core.h | 4 ++
> include/net/bluetooth/vendor_hci.h | 51 +++++++++++++++++++
> net/bluetooth/hci_core.c | 78 ++++++++++++++++++++++++++++++
> 4 files changed, 136 insertions(+)
> create mode 100644 include/net/bluetooth/vendor_hci.h
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 4c49f394f174..410d50dbd4e2 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -3738,6 +3738,9 @@ static int btusb_probe(struct usb_interface *intf,
> hdev->notify = btusb_notify;
>
> hdev->msft_ext.opcode = HCI_OP_NOP;
> + hdev->msft_ext.features = 0;
> + hdev->msft_ext.evt_prefix_len = 0;
> + hdev->msft_ext.evt_prefix = NULL;

as noted in the other review, let hci_alloc_dev and hci_free_dev deal with this.

>
> #ifdef CONFIG_PM
> err = btusb_config_oob_wake(hdev);
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 0ec3d9b41d81..f2876c5067a4 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -30,6 +30,7 @@
>
> #include <net/bluetooth/hci.h>
> #include <net/bluetooth/hci_sock.h>
> +#include <net/bluetooth/vendor_hci.h>
>
> /* HCI priority */
> #define HCI_PRIO_MAX 7
> @@ -246,6 +247,9 @@ struct amp_assoc {
>
> struct msft_vnd_ext {
> __u16 opcode;
> + __u64 features;
> + __u8 evt_prefix_len;
> + void *evt_prefix;
> };
>
> struct hci_dev {
> diff --git a/include/net/bluetooth/vendor_hci.h b/include/net/bluetooth/vendor_hci.h
> new file mode 100644
> index 000000000000..89a6795e672c
> --- /dev/null
> +++ b/include/net/bluetooth/vendor_hci.h
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * BlueZ - Bluetooth protocol stack for Linux
> + * Copyright (C) 2020 Google Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation;
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
> + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
> + * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
> + * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
> + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
> + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
> + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
> + *
> + * ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
> + * COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
> + * SOFTWARE IS DISCLAIMED.
> + */
> +
> +#ifndef __VENDOR_HCI_H
> +#define __VENDOR_HCI_H
> +
> +#define MSFT_EVT_PREFIX_MAX_LEN 255
> +
> +struct msft_cmd_cmp_info {
> + __u8 status;
> + __u8 sub_opcode;
> +} __packed;
> +
> +/* Microsoft Vendor HCI subcommands */
> +#define MSFT_OP_READ_SUPPORTED_FEATURES 0x00
> +#define MSFT_FEATURE_MASK_RSSI_MONITOR_BREDR_CONN 0x0000000000000001
> +#define MSFT_FEATURE_MASK_RSSI_MONITOR_LE_CONN 0x0000000000000002
> +#define MSFT_FEATURE_MASK_RSSI_MONITOR_LE_ADV 0x0000000000000004
> +#define MSFT_FEATURE_MASK_ADV_MONITOR_LE_ADV 0x0000000000000008
> +#define MSFT_FEATURE_MASK_VERIFY_CURVE 0x0000000000000010
> +#define MSFT_FEATURE_MASK_CONCURRENT_ADV_MONITOR 0x0000000000000020
> +struct msft_cp_read_supported_features {
> + __u8 sub_opcode;
> +} __packed;
> +struct msft_rp_read_supported_features {
> + __u64 features;
> + __u8 evt_prefix_len;
> + __u8 evt_prefix[0];
> +} __packed;
> +
> +#endif /* __VENDOR_HCI_H */

Lets put this all in net/bluetooth/msft.c for now.

> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index dbd2ad3a26ed..1ea32d10ed08 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1407,6 +1407,76 @@ static void hci_dev_get_bd_addr_from_property(struct hci_dev *hdev)
> bacpy(&hdev->public_addr, &ba);
> }
>
> +static void process_msft_vnd_ext_cmd_complete(struct hci_dev *hdev,
> + struct sk_buff *skb)
> +{
> + struct msft_cmd_cmp_info *info = (void *)skb->data;
> + const u8 status = info->status;
> + const u16 sub_opcode = __le16_to_cpu(info->sub_opcode);
> +
> + skb_pull(skb, sizeof(*info));
> +
> + if (IS_ERR(skb)) {
> + BT_WARN("%s: Microsoft extension response packet invalid",
> + hdev->name);
> + return;
> + }
> +
> + if (status) {
> + BT_WARN("%s: Microsoft extension sub command 0x%2.2x failed",
> + hdev->name, sub_opcode);
> + return;
> + }
> +
> + BT_DBG("%s: status 0x%2.2x sub opcode 0x%2.2x", hdev->name, status,
> + sub_opcode);
> +
> + switch (sub_opcode) {
> + case MSFT_OP_READ_SUPPORTED_FEATURES: {
> + struct msft_rp_read_supported_features *rp = (void *)skb->data;
> + u8 prefix_len = rp->evt_prefix_len;
> +
> + hdev->msft_ext.features = __le64_to_cpu(rp->features);
> + hdev->msft_ext.evt_prefix_len = prefix_len;
> + hdev->msft_ext.evt_prefix = kmalloc(prefix_len, GFP_ATOMIC);

Are we really in interrupt context here? I donât think there is a need for GFP_ATOMIC.

> + if (!hdev->msft_ext.evt_prefix) {
> + BT_WARN("%s: Microsoft extension invalid event prefix",
> + hdev->name);

Please start using bt_dev_warn etc.

> + return;
> + }
> +
> + memcpy(hdev->msft_ext.evt_prefix, rp->evt_prefix, prefix_len);
> + BT_INFO("%s: Microsoft extension features 0x%016llx",
> + hdev->name, hdev->msft_ext.features);
> + break;
> + }
> + default:
> + BT_WARN("%s: Microsoft extension unknown sub opcode 0x%2.2x",
> + hdev->name, sub_opcode);
> + break;
> + }
> +}
> +
> +static void read_vendor_extension_features(struct hci_dev *hdev)
> +{
> + struct sk_buff *skb;
> + const u16 msft_opcode = hdev->msft_ext.opcode;
> +
> + if (msft_opcode != HCI_OP_NOP) {

I really prefer it this way

if (!something_supported)
return;

> + struct msft_cp_read_supported_features cp;
> +
> + cp.sub_opcode = MSFT_OP_READ_SUPPORTED_FEATURES;
> + skb = __hci_cmd_sync(hdev, msft_opcode, sizeof(cp), &cp,
> + HCI_CMD_TIMEOUT);
> +
> + process_msft_vnd_ext_cmd_complete(hdev, skb);
> + if (skb) {
> + kfree_skb(skb);
> + skb = NULL;
> + }
> + }
> +}
> +
> static int hci_dev_do_open(struct hci_dev *hdev)
> {
> int ret = 0;
> @@ -1554,6 +1624,11 @@ static int hci_dev_do_open(struct hci_dev *hdev)
> }
> }
>
> + /* Check features supported by HCI extensions after the init procedure
> + * completed.
> + */
> + read_vendor_extension_features(hdev);
> +

msft_do_open(hdev);


> /* If the HCI Reset command is clearing all diagnostic settings,
> * then they need to be reprogrammed after the init procedure
> * completed.
> @@ -1733,6 +1808,9 @@ int hci_dev_do_close(struct hci_dev *hdev)
> cancel_delayed_work_sync(&adv_instance->rpa_expired_cb);
> }
>
> + kfree(hdev->msft_ext.evt_prefix);
> + hdev->msft_ext.evt_prefix = NULL;
> +

msft_do_close(hdev);


And let these two function clear, init, free etc. everything except hdev->msft_ext.opcode

That said, I would actually also introduce a wrapper msft_set_opcode(hdev, opcode); so that the driver doesnât have to know the internal on how that opcode is stored.

We can also keep the struct msft_ext internal to msft.c and donât have to expose the internal details. So all stay confined in net/bluetooth/msft.c.

> /* Avoid potential lockdep warnings from the *_flush() calls by
> * ensuring the workqueue is empty up front.
> */

Regards

Marcel