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 <32026740-96FE-4377-B5A1-2AEE324880D0@holtmann.org>
In-Reply-To: <32026740-96FE-4377-B5A1-2AEE324880D0@holtmann.org>
From:   Miao-chen Chou <mcchou@chromium.org>
Date:   Thu, 26 Mar 2020 00:51:01 -0700
Message-ID: <CABmPvSFzmuC0p7QFcXSG+NOfQ4QyDDd55AzaP7QOEsuwBs6j9Q@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] Bluetooth: btusb: Read the supported features of
 Microsoft vendor extension
To:     Marcel Holtmann <marcel@holtmann.org>
Cc:     Bluetooth Kernel Mailing List <linux-bluetooth@vger.kernel.org>,
        Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
        Alain Michaud <alainm@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>
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On Wed, Mar 25, 2020 at 1:25 AM Marcel Holtmann <marcel@holtmann.org> wrote=
:
>
> Hi Miao-chen,
>
> > This adds a new header to facilitate the opcode and packet structures o=
f
> > 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/driver=
s/
> > 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 featu=
res
> > of Microsoft vendor extension if the opcode of Microsoft vendor extensi=
on
> > 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 whe=
re
> > the Microsoft vendor extension features are 0x000000000000003f.
> >
> > Signed-off-by: Miao-chen Chou <mcchou@chromium.org>
> > ---
> >
> > 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 =3D btusb_notify;
> >
> >       hdev->msft_ext.opcode =3D HCI_OP_NOP;
> > +     hdev->msft_ext.features =3D 0;
> > +     hdev->msft_ext.evt_prefix_len =3D 0;
> > +     hdev->msft_ext.evt_prefix =3D NULL;
>
> as noted in the other review, let hci_alloc_dev and hci_free_dev deal wit=
h this.
Will address this in v3.
>
> >
> > #ifdef CONFIG_PM
> >       err =3D btusb_config_oob_wake(hdev);
> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/h=
ci_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 modif=
y
> > + * 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, EXP=
RESS
> > + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANT=
ABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY=
 RIGHTS.
> > + * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE F=
OR ANY
> > + * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAM=
AGES
> > + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN =
AN
> > + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OU=
T 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    0x000000000000000=
1
> > +#define MSFT_FEATURE_MASK_RSSI_MONITOR_LE_CONN               0x0000000=
000000002
> > +#define MSFT_FEATURE_MASK_RSSI_MONITOR_LE_ADV                0x0000000=
000000004
> > +#define MSFT_FEATURE_MASK_ADV_MONITOR_LE_ADV         0x000000000000000=
8
> > +#define MSFT_FEATURE_MASK_VERIFY_CURVE                       0x0000000=
000000010
> > +#define MSFT_FEATURE_MASK_CONCURRENT_ADV_MONITOR     0x000000000000002=
0
> > +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.
Will address in v3.
>
> > 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(st=
ruct 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 =3D (void *)skb->data;
> > +     const u8 status =3D info->status;
> > +     const u16 sub_opcode =3D __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 fail=
ed",
> > +                     hdev->name, sub_opcode);
> > +             return;
> > +     }
> > +
> > +     BT_DBG("%s: status 0x%2.2x sub opcode 0x%2.2x", hdev->name, statu=
s,
> > +            sub_opcode);
> > +
> > +     switch (sub_opcode) {
> > +     case MSFT_OP_READ_SUPPORTED_FEATURES: {
> > +             struct msft_rp_read_supported_features *rp =3D (void *)sk=
b->data;
> > +             u8 prefix_len =3D rp->evt_prefix_len;
> > +
> > +             hdev->msft_ext.features =3D __le64_to_cpu(rp->features);
> > +             hdev->msft_ext.evt_prefix_len =3D prefix_len;
> > +             hdev->msft_ext.evt_prefix =3D kmalloc(prefix_len, GFP_ATO=
MIC);
>
> Are we really in interrupt context here? I don=E2=80=99t think there is a=
 need for GFP_ATOMIC.
Not really, will change this to GFP_KERNEL.
>
> > +             if (!hdev->msft_ext.evt_prefix) {
> > +                     BT_WARN("%s: Microsoft extension invalid event pr=
efix",
> > +                             hdev->name);
>
> Please start using bt_dev_warn etc.
Will address in v3.
>
> > +                     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 =3D hdev->msft_ext.opcode;
> > +
> > +     if (msft_opcode !=3D  HCI_OP_NOP) {
>
> I really prefer it this way
>
>         if (!something_supported)
>                 return;
Will address in v3.
>
> > +             struct msft_cp_read_supported_features cp;
> > +
> > +             cp.sub_opcode =3D MSFT_OP_READ_SUPPORTED_FEATURES;
> > +             skb =3D __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 =3D NULL;
> > +             }
> > +     }
> > +}
> > +
> > static int hci_dev_do_open(struct hci_dev *hdev)
> > {
> >       int ret =3D 0;
> > @@ -1554,6 +1624,11 @@ static int hci_dev_do_open(struct hci_dev *hdev)
> >               }
> >       }
> >
> > +     /* Check features supported by HCI extensions after the init proc=
edure
> > +      * 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_expir=
ed_cb);
> >       }
> >
> > +     kfree(hdev->msft_ext.evt_prefix);
> > +     hdev->msft_ext.evt_prefix =3D 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 doesn=E2=80=99t have to know the internal on =
how that opcode is stored.
>
> We can also keep the struct msft_ext internal to msft.c and don=E2=80=99t=
 have to expose the internal details. So all stay confined in net/bluetooth=
/msft.c.
Good point. Will add net/bluetooth/msft.c in v3.
>
> >       /* Avoid potential lockdep warnings from the *_flush() calls by
> >        * ensuring the workqueue is empty up front.
> >        */
Regards,
Miao