linux.git/include/uapi/xen, branch v6.18.21

xen/privcmd: Add new syscall to get gsi from dev

2024-09-25T07:54:55+00:00

On PVH dom0, when passthrough a device to domU, QEMU and xl tools
want to use gsi number to do pirq mapping, see QEMU code
xen_pt_realize->xc_physdev_map_pirq, and xl code
pci_add_dm_done->xc_physdev_map_pirq, but in current codes, the gsi
number is got from file /sys/bus/pci/devices//irq, that is
wrong, because irq is not equal with gsi, they are in different
spaces, so pirq mapping fails.
And in current linux codes, there is no method to get gsi
for userspace.

For above purpose, record gsi of pcistub devices when init
pcistub and add a new syscall into privcmd to let userspace
can get gsi when they have a need.

Signed-off-by: Jiqian Chen 
Signed-off-by: Huang Rui 
Signed-off-by: Jiqian Chen 
Reviewed-by: Stefano Stabellini 
Message-ID: <20240924061437.2636766-4-Jiqian.Chen@amd.com>
Signed-off-by: Juergen Gross

xen/gntalloc: Replace UAPI 1-element array

2024-02-13T08:06:48+00:00

Without changing the structure size (since it is UAPI), add a proper
flexible array member, and reference it in the kernel so that it will
not be trip the array-bounds sanitizer[1].

Link: https://github.com/KSPP/linux/issues/113 [1]
Cc: Juergen Gross 
Cc: Stefano Stabellini 
Cc: Oleksandr Tyshchenko 
Cc: Gustavo A. R. Silva 
Cc: xen-devel@lists.xenproject.org
Signed-off-by: Kees Cook 
Reviewed-by: Gustavo A. R. Silva 
Link: https://lore.kernel.org/r/20240206170320.work.437-kees@kernel.org
Signed-off-by: Juergen Gross

xen: privcmd: Add support for ioeventfd

2023-10-16T13:18:33+00:00

Virtio guests send VIRTIO_MMIO_QUEUE_NOTIFY notification when they need
to notify the backend of an update to the status of the virtqueue. The
backend or another entity, polls the MMIO address for updates to know
when the notification is sent.

It works well if the backend does this polling by itself. But as we move
towards generic backend implementations, we end up implementing this in
a separate user-space program.

Generally, the Virtio backends are implemented to work with the Eventfd
based mechanism. In order to make such backends work with Xen, another
software layer needs to do the polling and send an event via eventfd to
the backend once the notification from guest is received. This results
in an extra context switch.

This is not a new problem in Linux though. It is present with other
hypervisors like KVM, etc. as well. The generic solution implemented in
the kernel for them is to provide an IOCTL call to pass the address to
poll and eventfd, which lets the kernel take care of polling and raise
an event on the eventfd, instead of handling this in user space (which
involves an extra context switch).

This patch adds similar support for xen.

Inspired by existing implementations for KVM, etc..

This also copies ioreq.h header file (only struct ioreq and related
macros) from Xen's source tree (Top commit 5d84f07fe6bf ("xen/pci: drop
remaining uses of bool_t")).

Signed-off-by: Viresh Kumar 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/b20d83efba6453037d0c099912813c79c81f7714.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross

xen: irqfd: Use _IOW instead of the internal _IOC() macro

2023-10-16T13:18:33+00:00

_IOC() an internal helper that we should not use in driver code.  In
particular, we got the data direction wrong here, which breaks a number
of tools, as having "_IOC_NONE" should never be paired with a nonzero
size.

Use _IOW() instead.

Fixes: f8941e6c4c71 ("xen: privcmd: Add support for irqfd")
Reported-by: Arnd Bergmann 
Closes: https://lore.kernel.org/all/268a2031-63b8-4c7d-b1e5-8ab83ca80b4a@app.fastmail.com/
Signed-off-by: Viresh Kumar 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/599ca6f1b9dd2f0e6247ea37bee3ea6827404b6d.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross

xen: Make struct privcmd_irqfd's layout architecture independent

2023-10-16T13:18:33+00:00

Using indirect pointers in an ioctl command argument means that the
layout is architecture specific, in particular we can't use the same one
from 32-bit compat tasks. The general recommendation is to have __u64
members and use u64_to_user_ptr() to access it from the kernel if we are
unable to avoid the pointers altogether.

Fixes: f8941e6c4c71 ("xen: privcmd: Add support for irqfd")
Reported-by: Arnd Bergmann 
Closes: https://lore.kernel.org/all/268a2031-63b8-4c7d-b1e5-8ab83ca80b4a@app.fastmail.com/
Signed-off-by: Viresh Kumar 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/a4ef0d4a68fc858b34a81fd3f9877d9b6898eb77.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross

xen: privcmd: Add support for irqfd

2023-08-22T10:12:50+00:00

Xen provides support for injecting interrupts to the guests via the
HYPERVISOR_dm_op() hypercall. The same is used by the Virtio based
device backend implementations, in an inefficient manner currently.

Generally, the Virtio backends are implemented to work with the Eventfd
based mechanism. In order to make such backends work with Xen, another
software layer needs to poll the Eventfds and raise an interrupt to the
guest using the Xen based mechanism. This results in an extra context
switch.

This is not a new problem in Linux though. It is present with other
hypervisors like KVM, etc. as well. The generic solution implemented in
the kernel for them is to provide an IOCTL call to pass the interrupt
details and eventfd, which lets the kernel take care of polling the
eventfd and raising of the interrupt, instead of handling this in user
space (which involves an extra context switch).

This patch adds support to inject a specific interrupt to guest using
the eventfd mechanism, by preventing the extra context switch.

Inspired by existing implementations for KVM, etc..

Signed-off-by: Viresh Kumar 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/8e724ac1f50c2bc1eb8da9b3ff6166f1372570aa.1692697321.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross

xen/evtchn: Introduce new IOCTL to bind static evtchn

2023-07-26T06:42:34+00:00

Xen 4.17 supports the creation of static evtchns. To allow user space
application to bind static evtchns introduce new ioctl
"IOCTL_EVTCHN_BIND_STATIC". Existing IOCTL doing more than binding
that’s why we need to introduce the new IOCTL to only bind the static
event channels.

Static evtchns to be available for use during the lifetime of the
guest. When the application exits, __unbind_from_irq() ends up being
called from release() file operations because of that static evtchns
are getting closed. To avoid closing the static event channel, add the
new bool variable "is_static" in "struct irq_info" to mark the event
channel static when creating the event channel to avoid closing the
static evtchn.

Also, take this opportunity to remove the open-coded version of the
evtchn close in drivers/xen/evtchn.c file and use xen_evtchn_close().

Signed-off-by: Rahul Singh 
Reviewed-by: Oleksandr Tyshchenko 
Acked-by: Stefano Stabellini 
Link: https://lore.kernel.org/r/ae7329bf1713f83e4aad4f3fa0f316258c40a3e9.1689677042.git.rahul.singh@arm.com
Signed-off-by: Juergen Gross

Improve docs for IOCTL_GNTDEV_MAP_GRANT_REF

2022-02-03T07:23:32+00:00

--------------cKY3Ggs6VDUCSn4I6iN78sHA
Content-Type: multipart/mixed; boundary="------------g0T69ASidFiPhh4eOY4XzIg1"

--------------g0T69ASidFiPhh4eOY4XzIg1
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

The current implementation of gntdev guarantees that the first call to
IOCTL_GNTDEV_MAP_GRANT_REF will set @index to 0.  This is required to
use gntdev for Wayland, which is a future desire of Qubes OS.
Additionally, requesting zero grants results in an error, but this was
not documented either.  Document both of these.

Signed-off-by: Demi Marie Obenour 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/f66c5a4e-2034-00b5-a635-6983bd999c07@gmail.com
Signed-off-by: Juergen Gross

xen/gntdev: gntdev.h: drop a duplicated word

2020-08-03T05:46:42+00:00

Drop the repeated word "of" in a comment.

Signed-off-by: Randy Dunlap 
Reviewed-by: Juergen Gross 
Cc: Boris Ostrovsky 
Cc: Juergen Gross 
Cc: xen-devel@lists.xenproject.org
Link: https://lore.kernel.org/r/20200719003317.21454-1-rdunlap@infradead.org
Signed-off-by: Juergen Gross

xen/gntdev: Add initial support for dma-buf UAPI

2018-07-27T03:05:14+00:00

Add UAPI and IOCTLs for dma-buf grant device driver extension:
the extension allows userspace processes and kernel modules to
use Xen backed dma-buf implementation. With this extension grant
references to the pages of an imported dma-buf can be exported
for other domain use and grant references coming from a foreign
domain can be converted into a local dma-buf for local export.
Implement basic initialization and stubs for Xen DMA buffers'
support.

Signed-off-by: Oleksandr Andrushchenko 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Boris Ostrovsky