xen: make remove callback of xen driver void returned

Since commit fc7a6209d571 ("bus: Make remove callback return void")
forces bus_type::remove be void-returned, it doesn't make much sense for
any bus based driver implementing remove callbalk to return non-void to
its caller.

This change is for xen bus based drivers.

Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Link: https://lore.kernel.org/r/TYCP286MB23238119AB4DF190997075C9CAE39@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM
Signed-off-by: Juergen Gross <jgross@suse.com>

xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()

Simplify xen-hcd's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juergen Gross <jgross@suse.com>

xen/usb: switch xen-hcd to use INVALID_GRANT_REF

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juergen Gross <jgross@suse.com>

xen/grant-table: remove readonly parameter from functions

The gnttab_end_foreign_access() family of functions is taking a
"readonly" parameter, which isn't used. Remove it from the function
parameters.

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220311103429.12845-3-jgross@suse.com
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

xen/usb: harden xen_hcd against malicious backends

Make sure a malicious backend can't cause any harm other than wrong
I/O data.

Missing are verification of the request id in a response, sanitizing
the reported actual I/O length, and protection against interrupt storms
from the backend.

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220311103509.12908-1-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xen/usb: don't use arbitrary_virt_to_machine()

arbitrary_virt_to_machine() is meant to be used in PV guests only.
Replace its usage with virt_to_gfn().

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220311103500.12885-1-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xen/usb: don't use gnttab_end_foreign_access() in xenhcd_gnttab_done()

The usage of gnttab_end_foreign_access() in xenhcd_gnttab_done() is
not safe against a malicious backend, as the backend could keep the
I/O page mapped and modify it even after the granted memory page is
being used for completely other purposes in the local system.

So replace that use case with gnttab_try_end_foreign_access() and
disable the PV host adapter in case the backend didn't stop using the
granted page.

In xenhcd_urb_request_done() immediately return in case of setting
the device state to "error" instead of looking into further backend
responses.

Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
V2:
- use gnttab_try_end_foreign_access()

usb: host: xen-hcd: add missing unlock in error path

Add the missing unlock before return from function xenhcd_urb_request_done()
and xenhcd_conn_notify() in the error handling case.

Fixes: 494ed3997d75 ("usb: Introduce Xen pvUSB frontend (xen hcd)")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20211215035805.375244-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb: Introduce Xen pvUSB frontend (xen hcd)

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@suse.com>
Link: https://lore.kernel.org/r/20211123132048.5335-3-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>