vringh: address kdoc warnings

Address some minor kdoc warnings in vring.h.
* Place kdoc for 'struct vringh_config_ops' immediately before the structure
* Add missing documentation of members of 'vringh_iov' and 'vringh_kiov'

Warnings flagged by:
$ ./scripts/kernel-doc -none include/linux/vringh.h
include/linux/vringh.h:68: error: Cannot parse struct or union!
include/linux/vringh.h:92: warning: Function parameter or member 'iov' not described in 'vringh_iov'
include/linux/vringh.h:92: warning: Function parameter or member 'consumed' not described in 'vringh_iov'
include/linux/vringh.h:92: warning: Function parameter or member 'i' not described in 'vringh_iov'
include/linux/vringh.h:92: warning: Function parameter or member 'used' not described in 'vringh_iov'
include/linux/vringh.h:92: warning: Function parameter or member 'max_num' not described in 'vringh_iov'
include/linux/vringh.h:104: warning: Function parameter or member 'iov' not described in 'vringh_kiov'
include/linux/vringh.h:104: warning: Function parameter or member 'consumed' not described in 'vringh_kiov'
include/linux/vringh.h:104: warning: Function parameter or member 'i' not described in 'vringh_kiov'
include/linux/vringh.h:104: warning: Function parameter or member 'used' not described in 'vringh_kiov'
include/linux/vringh.h:104: warning: Function parameter or member 'max_num' not described in 'vringh_kiov'

Signed-off-by: Simon Horman <horms@kernel.org>
Message-Id: <20230331-vhost-fixes-v1-2-1f046e735b9e@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: support VA with iotlb

vDPA supports the possibility to use user VA in the iotlb messages.
So, let's add support for user VA in vringh to use it in the vDPA
simulators.

Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20230404131716.45855-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: fix a typo in comments for vringh_kiov

Probably it is a simple copy error from struct vring_iov.

Signed-off-by: Shunsuke Mie <mie@igel.co.jp>
Message-Id: <20230202104248.2040652-1-mie@igel.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: pull in spinlock header

we use a spinlock now pull in the correct header to
make vring.h self sufficient.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: add vringh_kiov_length() helper

This new helper returns the total number of bytes covered by
a vringh_kiov.

Suggested-by: Jason Wang <jasowang@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-7-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: implement vringh_kiov_advance()

In some cases, it may be useful to provide a way to skip a number
of bytes in a vringh_kiov.

Let's implement vringh_kiov_advance() for this purpose, reusing the
code from vringh_iov_xfer().
We replace that code calling the new vringh_kiov_advance().

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-6-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: add 'iotlb_lock' to synchronize iotlb accesses

Usually iotlb accesses are synchronized with a spinlock.
Let's request it as a new parameter in vringh_set_iotlb() and
hold it when we navigate the iotlb in iotlb_translate() to avoid
race conditions with any new additions/deletions of ranges from
the ioltb.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-3-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

virtio: force spec specified alignment on types

The ring element addresses are passed between components with different
alignments assumptions. Thus, if guest/userspace selects a pointer and
host then gets and dereferences it, we might need to decrease the
compiler-selected alignment to prevent compiler on the host from
assuming pointer is aligned.

This actually triggers on ARM with -mabi=apcs-gnu - which is a
deprecated configuration, but it seems safer to handle this
generally.

Note that userspace that allocates the memory is actually OK and does
not need to be fixed, but userspace that gets it from guest or another
process does need to be fixed. The later doesn't generally talk to the
kernel so while it might be buggy it's not talking to the kernel in the
buggy way - it's just using the header in the buggy way - so fixing
header and asking userspace to recompile is the best we can do.

I verified that the produced kernel binary on x86 is exactly identical
before and after the change.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

virtio/test: fix up after IOTLB changes

Allow building vringh without IOTLB (that's the case for userspace
builds, will be useful for CAIF/VOD down the road too).
Update for API tweaks.
Don't include vringh with userspace builds.

Cc: Jason Wang <jasowang@redhat.com>
Cc: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

vringh: IOTLB support

This patch implements the third memory accessor for vringh besides
current kernel and userspace accessors. This idea is to allow vringh
to do the address translation through an IOTLB which is implemented
via vhost_map interval tree. Users should setup and IOVA to PA mapping
in this IOTLB.

This allows us to:

- Use vringh to access virtqueues with vIOMMU
- Use vringh to implement software virtqueues for vDPA devices

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200326140125.19794-5-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

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 write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

virtio: add explicit big-endian support to memory accessors

The current memory accessors logic is:
- little endian if little_endian
- native endian (i.e. no byteswap) if !little_endian

If we want to fully support cross-endian vhost, we also need to be
able to convert to big endian.

Instead of changing the little_endian argument to some 3-value enum, this
patch changes the logic to:
- little endian if little_endian
- big endian if !little_endian

The native endian case is handled by all users with a trivial helper. This
patch doesn't change any functionality, nor it does add overhead.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

vringh: introduce vringh_is_little_endian() helper

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

vringh: update for virtio 1.0 APIs

When switching everything over to virtio 1.0 memory access APIs,
I missed converting vringh.
Fortunately, it's straight-forward.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh: 64 bit features

Pass u64 everywhere.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

virtio: Introduce vringh wrappers in virtio_config

Add wrappers for the host vrings to support loose
coupling between the virtio device and driver.

A new struct vringh_config_ops with the functions
find_vrhs() and del_vrhs() is added to the virtio_device
struct. This enables virtio drivers to manage virtio
host rings without detailed knowledge of how the
vrings are created and deleted.

The function vringh_notify() is added so vringh clients
can notify the other side that buffers are added to the
used-ring.

Cc: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (constified vringh_config)

vringh: host-side implementation of virtio rings.

Getting use of virtio rings correct is tricky, and a recent patch saw
an implementation of in-kernel rings (as separate from userspace).

This abstracts the business of dealing with the virtio ring layout
from the access (userspace or direct); to do this, we use function
pointers, which gcc inlines correctly.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>