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Date: Tue, 16 Jun 2015 16:56:35 +0200
From: Juergen Gross <jgross@...e.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
konrad.wilk@...cle.com, david.vrabel@...rix.com,
boris.ostrovsky@...cle.com, linux-usb@...r.kernel.org
Subject: Re: [Patch V3 2/3] usb: Introduce Xen pvUSB frontend (xen hcd)
On 06/16/2015 04:45 PM, Greg KH wrote:
> On Tue, Jun 16, 2015 at 04:32:34PM +0200, Juergen Gross wrote:
>> Introduces the Xen pvUSB frontend. With pvUSB it is possible for a Xen
>> domU to communicate with a USB device assigned to that domU. The
>> communication is all done via the pvUSB backend in a driver domain
>> (usually Dom0) which is owner of the physical device.
>>
>> The pvUSB frontend is a USB hcd for a virtual USB host connector.
>>
>> The code is taken from the pvUSB implementation in Xen done by Fujitsu
>> based on Linux kernel 2.6.18.
>>
>> Changes from the original version are:
>> - port to upstream kernel
>> - put all code in just one source file
>> - move module to appropriate location in kernel tree
>> - adapt to Linux style guide
>> - minor code modifications to increase readability
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>> drivers/usb/host/Kconfig | 11 +
>> drivers/usb/host/Makefile | 1 +
>> drivers/usb/host/xen-hcd.c | 1638 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 1650 insertions(+)
>> create mode 100644 drivers/usb/host/xen-hcd.c
>>
>> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
>> index 197a6a3..3361b4b 100644
>> --- a/drivers/usb/host/Kconfig
>> +++ b/drivers/usb/host/Kconfig
>> @@ -788,3 +788,14 @@ config USB_HCD_TEST_MODE
>> This option is of interest only to developers who need to validate
>> their USB hardware designs. It is not needed for normal use. If
>> unsure, say N.
>> +
>> +config USB_XEN_HCD
>> + tristate "Xen usb virtual host driver"
>> + depends on XEN
>> + select XEN_XENBUS_FRONTEND
>> + help
>> + The Xen usb virtual host driver serves as a frontend driver enabling
>> + a Xen guest system to access USB Devices passed through to the guest
>> + by the Xen host (usually Dom0).
>> + Only needed if the kernel is running in a Xen guest and generic
>> + access to a USB device is needed.
>> diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
>> index 65b0b6a..3779696 100644
>> --- a/drivers/usb/host/Makefile
>> +++ b/drivers/usb/host/Makefile
>> @@ -75,3 +75,4 @@ obj-$(CONFIG_USB_HCD_SSB) += ssb-hcd.o
>> obj-$(CONFIG_USB_FUSBH200_HCD) += fusbh200-hcd.o
>> obj-$(CONFIG_USB_FOTG210_HCD) += fotg210-hcd.o
>> obj-$(CONFIG_USB_MAX3421_HCD) += max3421-hcd.o
>> +obj-$(CONFIG_USB_XEN_HCD) += xen-hcd.o
>> diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
>> new file mode 100644
>> index 0000000..9da2856
>> --- /dev/null
>> +++ b/drivers/usb/host/xen-hcd.c
>> @@ -0,0 +1,1638 @@
>> +/*
>> + * xen-hcd.c
>> + *
>> + * Xen USB Virtual Host Controller driver
>> + *
>> + * Copyright (C) 2009, FUJITSU LABORATORIES LTD.
>> + * Author: Noboru Iwamatsu <n_iwamatsu@...fujitsu.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
>> + *
>> + * Or, by your choice:
>> + *
>> + * When distributed separately from the Linux kernel or incorporated into
>> + * other software packages, subject to the following license:
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a copy
>> + * of this software and associated documentation files (the "Software"), to
>> + * deal in the Software without restriction, including without limitation the
>> + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
>> + * sell copies of the Software, and to permit persons to whom the Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be included in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * 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. IN NO EVENT SHALL THE
>> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
>> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
>> + * DEALINGS IN THE SOFTWARE.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/usb.h>
>> +#include <linux/list.h>
>> +#include <linux/usb/hcd.h>
>> +#include <linux/io.h>
>> +
>> +#include <xen/xen.h>
>> +#include <xen/xenbus.h>
>> +#include <xen/grant_table.h>
>> +#include <xen/events.h>
>> +#include <xen/page.h>
>> +
>> +#include <xen/interface/io/usbif.h>
>> +
>> +/* Private per-URB data */
>> +struct urb_priv {
>> + struct list_head list;
>> + struct urb *urb;
>> + int req_id; /* RING_REQUEST id for submitting */
>> + int unlink_req_id; /* RING_REQUEST id for unlinking */
>> + int status;
>> + unsigned unlinked:1; /* dequeued marker */
>> +};
>> +
>> +/* virtual roothub port status */
>> +struct rhport_status {
>> + __u32 status;
>> + unsigned resuming:1; /* in resuming */
>> + unsigned c_connection:1; /* connection changed */
>> + unsigned long timeout;
>> +};
>> +
>> +/* status of attached device */
>> +struct vdevice_status {
>> + int devnum;
>> + enum usb_device_state status;
>> + enum usb_device_speed speed;
>> +};
>> +
>> +/* RING request shadow */
>> +struct usb_shadow {
>> + struct xenusb_urb_request req;
>> + struct urb *urb;
>> +};
>> +
>> +struct xenhcd_info {
>> + /* Virtual Host Controller has 4 urb queues */
>> + struct list_head pending_submit_list;
>> + struct list_head pending_unlink_list;
>> + struct list_head in_progress_list;
>> + struct list_head giveback_waiting_list;
>> +
>> + spinlock_t lock;
>> +
>> + /* timer that kick pending and giveback waiting urbs */
>> + struct timer_list watchdog;
>> + unsigned long actions;
>> +
>> + /* virtual root hub */
>> + int rh_numports;
>> + struct rhport_status ports[XENUSB_MAX_PORTNR];
>> + struct vdevice_status devices[XENUSB_MAX_PORTNR];
>> +
>> + /* Xen related staff */
>> + struct xenbus_device *xbdev;
>> + int urb_ring_ref;
>> + int conn_ring_ref;
>> + struct xenusb_urb_front_ring urb_ring;
>> + struct xenusb_conn_front_ring conn_ring;
>> +
>> + unsigned int evtchn;
>> + unsigned int irq;
>> + struct usb_shadow shadow[XENUSB_URB_RING_SIZE];
>> + unsigned shadow_free;
>> +};
>> +
>> +#define GRANT_INVALID_REF 0
>> +
>> +#define XENHCD_RING_JIFFIES (HZ/200)
>> +#define XENHCD_SCAN_JIFFIES 1
>> +
>> +enum xenhcd_timer_action {
>> + TIMER_RING_WATCHDOG,
>> + TIMER_SCAN_PENDING_URBS,
>> +};
>> +
>> +static struct kmem_cache *xenhcd_urbp_cachep;
>> +
>> +static inline struct xenhcd_info *xenhcd_hcd_to_info(struct usb_hcd *hcd)
>> +{
>> + return (struct xenhcd_info *)hcd->hcd_priv;
>> +}
>> +
>> +static inline struct usb_hcd *xenhcd_info_to_hcd(struct xenhcd_info *info)
>> +{
>> + return container_of((void *)info, struct usb_hcd, hcd_priv);
>> +}
>> +
>> +static inline void xenhcd_timer_action_done(struct xenhcd_info *info,
>> + enum xenhcd_timer_action action)
>> +{
>> + clear_bit(action, &info->actions);
>> +}
>> +
>> +static void xenhcd_timer_action(struct xenhcd_info *info,
>> + enum xenhcd_timer_action action)
>> +{
>> + if (timer_pending(&info->watchdog) &&
>> + test_bit(TIMER_SCAN_PENDING_URBS, &info->actions))
>> + return;
>> +
>> + if (!test_and_set_bit(action, &info->actions)) {
>> + unsigned long t;
>> +
>> + switch (action) {
>> + case TIMER_RING_WATCHDOG:
>> + t = XENHCD_RING_JIFFIES;
>> + break;
>> + default:
>> + t = XENHCD_SCAN_JIFFIES;
>> + break;
>> + }
>> + mod_timer(&info->watchdog, t + jiffies);
>> + }
>> +}
>> +
>> +static ssize_t xenhcd_show_statistics(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct usb_hcd *hcd;
>> + struct xenhcd_info *info;
>> + unsigned long flags;
>> + unsigned size;
>> +
>> + hcd = dev_get_drvdata(dev);
>> + info = xenhcd_hcd_to_info(hcd);
>> +
>> + spin_lock_irqsave(&info->lock, flags);
>> +
>> + size = scnprintf(buf, PAGE_SIZE, "bus %s, device %s\n%s\n"
>> + "xenhcd, hcd state %d\n",
>> + hcd->self.controller->bus->name,
>> + dev_name(hcd->self.controller), hcd->product_desc,
>> + hcd->state);
>> +
>> + spin_unlock_irqrestore(&info->lock, flags);
>> +
>> + return size;
>> +}
>> +
>> +static DEVICE_ATTR(statistics, S_IRUGO, xenhcd_show_statistics, NULL);
>
> DEVICE_ATTR_RO() please.
Okay.
> As you are adding new sysfs files, we need Documentation/ABI/ entries.
Okay.
> Also note that I will reject this sysfs file for the obvious reasons
> that it violates the one-value-per-file sysfs rule. Nice try to sneak
> this one by, don't ever do that again.
Lesson learned.
Hmm, I'm beginning to question the value of that file. May be I should
just throw it away.
Thanks for the quick feedback.
Juergen
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