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xen: add a grant-table user-space device

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A grant-table user-space device will allow user-space applications to map
and share grants (Xen way to share memory) among Xen domains. This grant
table user-space device has been tested with the QEMU Qdisk Xen backed.

Submitted by:		jaggi
Reviewed by:		royger
Differential review:	https://reviews.freebsd.org/D7293
This commit is contained in:
Roger Pau Monné 2016-10-31 13:12:58 +00:00
parent 0f4d7d9fd7
commit 78eb32933b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=308128
3 changed files with 1468 additions and 0 deletions
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1
sys/conf/files
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@ -3183,6 +3183,7 @@ dev/xen/xenstore/xenstore_dev.c optional xenhvm
dev/xen/xenstore/xenstored_dev.c optional xenhvm
dev/xen/evtchn/evtchn_dev.c optional xenhvm
dev/xen/privcmd/privcmd.c optional xenhvm
dev/xen/gntdev/gntdev.c optional xenhvm
dev/xen/debug/debug.c optional xenhvm
dev/xl/if_xl.c optional xl pci
dev/xl/xlphy.c optional xl pci

1275
sys/dev/xen/gntdev/gntdev.c Normal file
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192
sys/xen/gntdev.h Normal file
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@ -0,0 +1,192 @@
/*-
* Copyright (c) 2016 Akshay Jaggi <jaggi@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* gntdev.h
*
* Interface to /dev/xen/gntdev.
*
* This device provides the user with two kinds of functionalities:
* 1. Grant Allocation
* Allocate a page of our own memory, and share it with a foreign domain.
* 2. Grant Mapping
* Map a grant allocated by a foreign domain, into our own memory.
*
*
* Grant Allocation
*
* Steps to allocate a grant:
* 1. Do an `IOCTL_GNTDEV_ALLOC_GREF ioctl`, with
* - `domid`, as the domain-id of the foreign domain
* - `flags`, ORed with GNTDEV_ALLOC_FLAG_WRITABLE if you want the foreign
* domain to have write access to the shared memory
* - `count`, with the number of pages to share with the foreign domain
*
* Ensure that the structure you allocate has enough memory to store
* all the allocated grant-refs, i.e., you need to allocate
* (sizeof(struct ioctl_gntdev_alloc_gref) + (count - 1)*sizeof(uint32_t))
* bytes of memory.
*
* 2. Mmap the address given in `index` after a successful ioctl.
* This will give you access to the granted pages.
*
* Note:
* 1. The grant is not removed until all three of the following conditions
* are met
* - The region is not mmaped. That is, munmap() has been called if
* the region was mmapped previously.
* - IOCTL_GNTDEV_DEALLOC_GREF ioctl has been performed. After you
* perform this ioctl, you can no longer mmap or set notify on
* the grant.
* - The foreign domain has stopped using the grant.
* 2. Granted pages can only belong to one mmap region.
* 3. Every page of granted memory is a unit in itself. What this means
* is that you can set a unmap notification for each of the granted
* pages, individually; you can mmap and dealloc-ioctl a contiguous
* range of allocated grants (even if alloc-ioctls were performed
* individually), etc.
*
*
* Grant Mapping
*
* Steps to map a grant:
* 1. Do a `IOCTL_GNTDEV_MAP_GRANT_REF` ioctl, with
* - `count`, as the number of foreign grants to map
* - `refs[i].domid`, as the domain id of the foreign domain
* - `refs[i].ref`, as the grant-ref for the grant to be mapped
*
* 2. Mmap the address given in `index` after a successful ioctl.
* This will give you access to the mapped pages.
*
* Note:
* 1. The map hypercall is not made till the region is mmapped.
* 2. The unit is defined by the map ioctl. This means that only one
* unmap notification can be set on a group of pages that were
* mapped together in one ioctl, and also no single mmaping of contiguous
* grant-maps is possible.
* 3. You can mmap the same grant-map region multiple times.
* 4. The grant is not unmapped until both of the following conditions are met
* - The region is not mmaped. That is, munmap() has been called for
* as many times as the grant was mmapped.
* - IOCTL_GNTDEV_UNMAP_GRANT_REF ioctl has been called.
* 5. IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR ioctl gives index and count of
* a grant-map from the virtual address of the location where the grant
* is mmapped.
*
*
* IOCTL_GNTDEV_SET_UNMAP_NOTIFY
* This ioctl allows us to set notifications to be made when the grant is
* either unmapped (in case of a mapped grant), or when it is ready to be
* deallocated by us, ie, the grant is no more mmapped, and the dealloc
* ioctl has been called (in case of an allocated grant). OR `action` with
* the required notification masks, and fill in the appropriate fields.
* - UNMAP_NOTIFY_CLEAR_BYTE clears the byte at `index`, where index is
* the address of the byte in file address space.
* - UNMAP_NOTIFY_SEND_EVENT sends an event channel notification on
* `event_channel_port`
* In case of multiple notify ioctls, only the last one survives.
*
* $FreeBSD$
*/
#ifndef __XEN_GNTDEV_H__
#define __XEN_GNTDEV_H__
#include <sys/types.h>
#define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
_IOW('E', 0, struct ioctl_gntdev_unmap_notify)
struct ioctl_gntdev_unmap_notify {
/* IN parameters */
uint64_t index;
uint32_t action;
uint32_t event_channel_port;
};
#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
#define UNMAP_NOTIFY_SEND_EVENT 0x2
/*-------------------- Grant Allocation IOCTLs ------------------------------*/
#define IOCTL_GNTDEV_ALLOC_GREF \
_IOWR('E', 1, struct ioctl_gntdev_alloc_gref)
struct ioctl_gntdev_alloc_gref {
/* IN parameters */
uint16_t domid;
uint16_t flags;
uint32_t count;
/* OUT parameters */
uint64_t index;
/* Variable OUT parameter */
uint32_t gref_ids[1];
};
#define GNTDEV_ALLOC_FLAG_WRITABLE 1
#define IOCTL_GNTDEV_DEALLOC_GREF \
_IOW('E', 2, struct ioctl_gntdev_dealloc_gref)
struct ioctl_gntdev_dealloc_gref {
/* IN parameters */
uint64_t index;
uint32_t count;
};
/*-------------------- Grant Mapping IOCTLs ---------------------------------*/
struct ioctl_gntdev_grant_ref {
uint32_t domid;
uint32_t ref;
};
#define IOCTL_GNTDEV_MAP_GRANT_REF \
_IOWR('E', 3, struct ioctl_gntdev_map_grant_ref)
struct ioctl_gntdev_map_grant_ref {
/* IN parameters */
uint32_t count;
uint32_t pad0;
/* OUT parameters */
uint64_t index;
/* Variable IN parameter */
struct ioctl_gntdev_grant_ref refs[1];
};
#define IOCTL_GNTDEV_UNMAP_GRANT_REF \
_IOW('E', 4, struct ioctl_gntdev_unmap_grant_ref)
struct ioctl_gntdev_unmap_grant_ref {
/* IN parameters */
uint64_t index;
uint32_t count;
};
#define IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR \
_IOWR('E', 5, struct ioctl_gntdev_get_offset_for_vaddr)
struct ioctl_gntdev_get_offset_for_vaddr {
/* IN parameters */
uint64_t vaddr;
/* OUT parameters */
uint64_t offset;
uint32_t count;
};
#endif /* __XEN_GNTDEV_H__ */