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/*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef XENFOREIGNMEMORY_H
#define XENFOREIGNMEMORY_H
/*
* This library allows you to map foreign domain memory, subject to
* permissions for both the process and the domain in which the
* process runs.
*/
#include <stdint.h>
#include <stddef.h>
#include <xen/xen.h>
/* Callers who don't care don't need to #include <xentoollog.h> */
struct xentoollog_logger;
typedef struct xenforeignmemory_handle xenforeignmemory_handle;
/*
* Return a handle onto the foreign memory mapping driver. Logs errors.
*
* Note: After fork(2) a child process must not use any opened
* foreignmemory handle inherited from their parent, nor access any
* grant mapped areas associated with that handle.
*
* The child must open a new handle if they want to interact with
* foreignmemory.
*
* Calling exec(2) in a child will safely (and reliably) reclaim any
* resources which were allocated via a xenforeignmemory_handle in the
* parent.
*
* A child which does not call exec(2) may safely call
* xenforeignmemory_close() on a xenforeignmemory_handle inherited
* from their parent. This will attempt to reclaim any resources
* associated with that handle. Note that in some implementations this
* reclamation may not be completely effective, in this case any
* affected resources remain allocated.
*
* Calling xenforeignmemory_close() is the only safe operation on a
* xenforeignmemory_handle which has been inherited.
*/
xenforeignmemory_handle *xenforeignmemory_open(struct xentoollog_logger *logger,
unsigned open_flags);
/*
* Close a handle previously allocated with xenforeignmemory_open().
*
* Under normal circumstances (i.e. not in the child after a fork)
* xenforeignmemory_unmap() should be used on all mappings allocated
* by xenforeignmemory_map() prior to closing the handle in order to
* free up resources associated with those mappings.
*
* This is the only function which may be safely called on a
* xenforeignmemory_handle in a child after a
* fork. xenforeignmemory_unmap() must not be called under such
* circumstances.
*/
int xenforeignmemory_close(xenforeignmemory_handle *fmem);
/*
* Maps a range within one domain to a local address range. Mappings
* must be unmapped with xenforeignmemory_unmap and should follow the
* same rules as mmap regarding page alignment.
*
* prot is as for mmap(2).
*
* @arr is an array of @pages gfns to be mapped linearly in the local
* address range. @err is an (optional) output array used to report
* per-page errors, as errno values.
*
* If @err is given (is non-NULL) then the mapping may partially
* succeed and return a valid pointer while also using @err to
* indicate the success (0) or failure (errno value) of the individual
* pages. The global errno thread local variable is not valid in this
* case.
*
* If @err is not given (is NULL) then on failure to map any page any
* successful mappings will be undone and NULL will be returned. errno
* will be set to correspond to the first failure (which may not be
* the most critical).
*
* It is also possible to return NULL due to a complete failure,
* i.e. failure to even attempt the mapping, in this case the global
* errno will have been set and the contents of @err (if given) is
* invalid.
*
* Note that it is also possible to return non-NULL with the contents
* of @err indicating failure to map every page.
*/
void *xenforeignmemory_map(xenforeignmemory_handle *fmem, uint32_t dom,
int prot, size_t pages,
const xen_pfn_t arr[/*pages*/], int err[/*pages*/]);
/*
* Almost like the previous one but also accepts two additional parameters:
*
* @addr is used as a hint address for foreign map placement (see mmap(2)).
* @flags is a set of additional flags as for mmap(2). Not all of the flag
* combinations are possible due to implementation details on different
* platforms.
*/
void *xenforeignmemory_map2(xenforeignmemory_handle *fmem, uint32_t dom,
void *addr, int prot, int flags, size_t pages,
const xen_pfn_t arr[/*pages*/], int err[/*pages*/]);
/*
* Unmap a mapping previous created with xenforeignmemory_map().
*
* Returns 0 on success on failure sets errno and returns -1.
*/
int xenforeignmemory_unmap(xenforeignmemory_handle *fmem,
void *addr, size_t pages);
/**
* This function restricts the use of this handle to the specified
* domain.
*
* @parm fmem handle to the open foreignmemory interface
* @parm domid the domain id
* @return 0 on success, -1 on failure.
*/
int xenforeignmemory_restrict(xenforeignmemory_handle *fmem,
domid_t domid);
typedef struct xenforeignmemory_resource_handle xenforeignmemory_resource_handle;
/**
* This function maps a guest resource.
*
* @parm fmem handle to the open foreignmemory interface
* @parm domid the domain id
* @parm type the resource type
* @parm id the type-specific resource identifier
* @parm frame base frame index within the resource
* @parm nr_frames number of frames to map
* @parm paddr pointer to an address passed through to mmap(2)
* @parm prot passed through to mmap(2)
* @parm POSIX-only flags passed through to mmap(2)
* @return pointer to foreignmemory resource handle on success, NULL on
* failure
*
* *paddr is used, on entry, as a hint address for foreign map placement
* (see mmap(2)) so should be set to NULL if no specific placement is
* required. On return *paddr contains the address where the resource is
* mapped.
* As for xenforeignmemory_map2() flags is a set of additional flags
* for mmap(2). Not all of the flag combinations are possible due to
* implementation details on different platforms.
*/
xenforeignmemory_resource_handle *xenforeignmemory_map_resource(
xenforeignmemory_handle *fmem, domid_t domid, unsigned int type,
unsigned int id, unsigned long frame, unsigned long nr_frames,
void **paddr, int prot, int flags);
/**
* This function releases a previously acquired resource.
*
* @parm fmem handle to the open foreignmemory interface
* @parm fres handle to the acquired resource
*
* Returns 0 on success on failure sets errno and returns -1.
*/
int xenforeignmemory_unmap_resource(
xenforeignmemory_handle *fmem, xenforeignmemory_resource_handle *fres);
/**
* Determine the maximum size of a specific resource.
*
* @parm fmem handle to the open foreignmemory interface
* @parm domid the domain id
* @parm type the resource type
* @parm id the type-specific resource identifier
*
* Return 0 on success and fills in *size, with a value in bytes. Sets errno
* and return -1 on error.
*/
int xenforeignmemory_resource_size(
xenforeignmemory_handle *fmem, domid_t domid, unsigned int type,
unsigned int id, size_t *size);
#endif
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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