linux/include/uapi/xen/privcmd.h
Viresh Kumar f0d7db7b33 xen: privcmd: Add support for ioeventfd
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 <viresh.kumar@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/b20d83efba6453037d0c099912813c79c81f7714.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross <jgross@suse.com>
2023-10-16 15:18:33 +02:00

162 lines
4.8 KiB
C

/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR MIT) */
/******************************************************************************
* privcmd.h
*
* Interface to /proc/xen/privcmd.
*
* Copyright (c) 2003-2005, K A Fraser
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation; or, 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 source file (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.
*/
#ifndef __LINUX_PUBLIC_PRIVCMD_H__
#define __LINUX_PUBLIC_PRIVCMD_H__
#include <linux/types.h>
#include <linux/compiler.h>
#include <xen/interface/xen.h>
struct privcmd_hypercall {
__u64 op;
__u64 arg[5];
};
struct privcmd_mmap_entry {
__u64 va;
/*
* This should be a GFN. It's not possible to change the name because
* it's exposed to the user-space.
*/
__u64 mfn;
__u64 npages;
};
struct privcmd_mmap {
int num;
domid_t dom; /* target domain */
struct privcmd_mmap_entry __user *entry;
};
struct privcmd_mmapbatch {
int num; /* number of pages to populate */
domid_t dom; /* target domain */
__u64 addr; /* virtual address */
xen_pfn_t __user *arr; /* array of mfns - or'd with
PRIVCMD_MMAPBATCH_*_ERROR on err */
};
#define PRIVCMD_MMAPBATCH_MFN_ERROR 0xf0000000U
#define PRIVCMD_MMAPBATCH_PAGED_ERROR 0x80000000U
struct privcmd_mmapbatch_v2 {
unsigned int num; /* number of pages to populate */
domid_t dom; /* target domain */
__u64 addr; /* virtual address */
const xen_pfn_t __user *arr; /* array of mfns */
int __user *err; /* array of error codes */
};
struct privcmd_dm_op_buf {
void __user *uptr;
size_t size;
};
struct privcmd_dm_op {
domid_t dom;
__u16 num;
const struct privcmd_dm_op_buf __user *ubufs;
};
struct privcmd_mmap_resource {
domid_t dom;
__u32 type;
__u32 id;
__u32 idx;
__u64 num;
__u64 addr;
};
/* For privcmd_irqfd::flags */
#define PRIVCMD_IRQFD_FLAG_DEASSIGN (1 << 0)
struct privcmd_irqfd {
__u64 dm_op;
__u32 size; /* Size of structure pointed by dm_op */
__u32 fd;
__u32 flags;
domid_t dom;
__u8 pad[2];
};
/* For privcmd_ioeventfd::flags */
#define PRIVCMD_IOEVENTFD_FLAG_DEASSIGN (1 << 0)
struct privcmd_ioeventfd {
__u64 ioreq;
__u64 ports;
__u64 addr;
__u32 addr_len;
__u32 event_fd;
__u32 vcpus;
__u32 vq;
__u32 flags;
domid_t dom;
__u8 pad[2];
};
/*
* @cmd: IOCTL_PRIVCMD_HYPERCALL
* @arg: &privcmd_hypercall_t
* Return: Value returned from execution of the specified hypercall.
*
* @cmd: IOCTL_PRIVCMD_MMAPBATCH_V2
* @arg: &struct privcmd_mmapbatch_v2
* Return: 0 on success (i.e., arg->err contains valid error codes for
* each frame). On an error other than a failed frame remap, -1 is
* returned and errno is set to EINVAL, EFAULT etc. As an exception,
* if the operation was otherwise successful but any frame failed with
* -ENOENT, then -1 is returned and errno is set to ENOENT.
*/
#define IOCTL_PRIVCMD_HYPERCALL \
_IOC(_IOC_NONE, 'P', 0, sizeof(struct privcmd_hypercall))
#define IOCTL_PRIVCMD_MMAP \
_IOC(_IOC_NONE, 'P', 2, sizeof(struct privcmd_mmap))
#define IOCTL_PRIVCMD_MMAPBATCH \
_IOC(_IOC_NONE, 'P', 3, sizeof(struct privcmd_mmapbatch))
#define IOCTL_PRIVCMD_MMAPBATCH_V2 \
_IOC(_IOC_NONE, 'P', 4, sizeof(struct privcmd_mmapbatch_v2))
#define IOCTL_PRIVCMD_DM_OP \
_IOC(_IOC_NONE, 'P', 5, sizeof(struct privcmd_dm_op))
#define IOCTL_PRIVCMD_RESTRICT \
_IOC(_IOC_NONE, 'P', 6, sizeof(domid_t))
#define IOCTL_PRIVCMD_MMAP_RESOURCE \
_IOC(_IOC_NONE, 'P', 7, sizeof(struct privcmd_mmap_resource))
#define IOCTL_PRIVCMD_IRQFD \
_IOW('P', 8, struct privcmd_irqfd)
#define IOCTL_PRIVCMD_IOEVENTFD \
_IOW('P', 9, struct privcmd_ioeventfd)
#endif /* __LINUX_PUBLIC_PRIVCMD_H__ */