From 8db99b422a6de4d19a93429a221e26afa03f32ef Mon Sep 17 00:00:00 2001

From: Gerd Hoffmann <kraxel@redhat.com>

Date: Mon, 3 Jun 2019 13:45:47 +0200

Subject: [PATCH 4/9] Introduce new "no_guest_reset" parameter for usb-host

 device

RH-Author: Gerd Hoffmann <kraxel@redhat.com>

Message-id: <20190603134550.30153-2-kraxel@redhat.com>

Patchwork-id: 88446

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 1/4] Introduce new "no_guest_reset" parameter for usb-host device

Bugzilla: 1710861

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Alexander Kappner <agk@godking.net>

With certain USB devices passed through via usb-host, a guest attempting to

reset a usb-host device can trigger a reset loop that renders the USB device

unusable. In my use case, the device was an iPhone XR that was passed through to

a Mac OS X Mojave guest. Upon connecting the device, the following happens:

1) Guest recognizes new device, sends reset to emulated USB host

2) QEMU's USB host sends reset to host kernel

3) Host kernel resets device

4) After reset, host kernel determines that some part of the device descriptor

has changed ("device firmware changed" in dmesg), so host kernel decides to

re-enumerate the device.

5) Re-enumeration causes QEMU to disconnect and reconnect the device in the

guest.

6) goto 1)

Here's from the host kernel (note the "device firmware changed" lines")

[3677704.473050] usb 1-1.3: new high-speed USB device number 53 using ehci-pci

[3677704.555594] usb 1-1.3: New USB device found, idVendor=05ac, idProduct=12a8, bcdDevice=11.08

[3677704.555599] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[3677704.555602] usb 1-1.3: Product: iPhone

[3677704.555605] usb 1-1.3: Manufacturer: Apple Inc.

[3677704.555607] usb 1-1.3: SerialNumber: [[removed]]

[3677709.401040] usb 1-1.3: reset high-speed USB device number 53 using ehci-pci

[3677709.479486] usb 1-1.3: device firmware changed

[3677709.479842] usb 1-1.3: USB disconnect, device number 53

[3677709.546039] usb 1-1.3: new high-speed USB device number 54 using ehci-pci

[3677709.627471] usb 1-1.3: New USB device found, idVendor=05ac, idProduct=12a8, bcdDevice=11.08

[3677709.627476] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[3677709.627479] usb 1-1.3: Product: iPhone

[3677709.627481] usb 1-1.3: Manufacturer: Apple Inc.

[3677709.627483] usb 1-1.3: SerialNumber: [[removed]]

[3677762.320044] usb 1-1.3: reset high-speed USB device number 54 using ehci-pci

[3677762.615630] usb 1-1.3: USB disconnect, device number 54

[3677762.787043] usb 1-1.3: new high-speed USB device number 55 using ehci-pci

[3677762.869016] usb 1-1.3: New USB device found, idVendor=05ac, idProduct=12a8, bcdDevice=11.08

[3677762.869024] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[3677762.869028] usb 1-1.3: Product: iPhone

[3677762.869032] usb 1-1.3: Manufacturer: Apple Inc.

[3677762.869035] usb 1-1.3: SerialNumber: [[removed]]

[3677815.662036] usb 1-1.3: reset high-speed USB device number 55 using ehci-pci

Here's from QEMU:

libusb: error [_get_usbfs_fd] libusb couldn't open USB device /dev/bus/usb/005/022: No such file or directory

libusb: error [udev_hotplug_event] ignoring udev action bind

libusb: error [udev_hotplug_event] ignoring udev action bind

libusb: error [_open_sysfs_attr] open /sys/bus/usb/devices/5-1/bConfigurationValue failed ret=-1 errno=2

libusb: error [_get_usbfs_fd] File doesn't exist, wait 10 ms and try again

libusb: error [_get_usbfs_fd] libusb couldn't open USB device /dev/bus/usb/005/024: No such file or directory

libusb: error [udev_hotplug_event] ignoring udev action bind

libusb: error [udev_hotplug_event] ignoring udev action bind

libusb: error [_open_sysfs_attr] open /sys/bus/usb/devices/5-1/bConfigurationValue failed ret=-1 errno=2

libusb: error [_get_usbfs_fd] File doesn't exist, wait 10 ms and try again

libusb: error [_get_usbfs_fd] libusb couldn't open USB device /dev/bus/usb/005/026: No such file or directory

The result of this is that the device remains permanently unusable in the guest.

The same problem has been previously reported for an iPad:

https://stackoverflow.com/questions/52617634/how-do-i-get-qemu-usb-passthrough-to-work-for-ipad-iphone

This problem can be elegantly solved by interrupting step 2) above. Instead of

passing through the reset, QEMU simply ignores it. To allow this to be

configured on a per-device level,  a new parameter "no_guest_reset" is

introduced for the usb-host device. I can confirm that the configuration

described above (iPhone XS + Mojave guest) works flawlessly with

no_guest_reset=True specified.

Working command line for my scenario:

device_add usb-host,vendorid=0x05ac,productid=0x12a8,no_guest_reset=True,id=iphone

Best regards

Alexander

Signed-off-by: Alexander Kappner <agk@godking.net>

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Message-id: 20190128140027.9448-1-kraxel@redhat.com

[ kraxel: rename parameter to "guest-reset" ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

(cherry picked from commit ba4c735b4fc74e309ce4b2551d258e442ef513a5)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/usb/host-libusb.c | 7 ++++++-

 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c

index 0290fb8..0425f0e 100644

--- a/hw/usb/host-libusb.c

+++ b/hw/usb/host-libusb.c

@@ -82,7 +82,7 @@ struct USBHostDevice {

     uint32_t                         options;

     uint32_t                         loglevel;

     bool                             needs_autoscan;

-

+    bool                             allow_guest_reset;

     /* state */

     QTAILQ_ENTRY(USBHostDevice)      next;

     int                              seen, errcount;

@@ -1447,6 +1447,10 @@ static void usb_host_handle_reset(USBDevice *udev)

     USBHostDevice *s = USB_HOST_DEVICE(udev);

     int rc;

+    if (!s->allow_guest_reset) {

+        return;

+    }

+

     trace_usb_host_reset(s->bus_num, s->addr);

     rc = libusb_reset_device(s->dh);

@@ -1564,6 +1568,7 @@ static Property usb_host_dev_properties[] = {

     DEFINE_PROP_UINT32("productid", USBHostDevice, match.product_id, 0),

     DEFINE_PROP_UINT32("isobufs",  USBHostDevice, iso_urb_count,    4),

     DEFINE_PROP_UINT32("isobsize", USBHostDevice, iso_urb_frames,   32),

+    DEFINE_PROP_BOOL("guest-reset", USBHostDevice, allow_guest_reset, true),

     DEFINE_PROP_UINT32("loglevel",  USBHostDevice, loglevel,

                        LIBUSB_LOG_LEVEL_WARNING),

     DEFINE_PROP_BIT("pipeline",    USBHostDevice, options,

-- 

1.8.3.1