Skip to content

Commit

Permalink
xen: sync include/xen/interface/io/ring.h with Xen's newest version
Browse files Browse the repository at this point in the history 
Sync include/xen/interface/io/ring.h with Xen's newest version in
order to get the RING_COPY_RESPONSE() and RING_RESPONSE_PROD_OVERFLOW()
macros.

Note that this will correct the wrong license info by adding the
missing original copyright notice.

Signed-off-by: Juergen Gross <[email protected]>
  • Loading branch information
@jgross1
jgross1 committed Jul 5, 2021
1 parent 2060061 commit 629a5d8
Showing 1 changed file with 156 additions and 122 deletions.
278 changes: 156 additions & 122 deletions include/xen/interface/io/ring.h
View file
Original file line number Diff line number Diff line change
@@ -1,21 +1,53 @@
/* SPDX-License-Identifier: GPL-2.0 */
/******************************************************************************
* ring.h
*
* Shared producer-consumer ring macros.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (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.
*
* Tim Deegan and Andrew Warfield November 2004.
*/

#ifndef __XEN_PUBLIC_IO_RING_H__
#define __XEN_PUBLIC_IO_RING_H__

/*
* When #include'ing this header, you need to provide the following
* declaration upfront:
* - standard integers types (uint8_t, uint16_t, etc)
* They are provided by stdint.h of the standard headers.
*
* In addition, if you intend to use the FLEX macros, you also need to
* provide the following, before invoking the FLEX macros:
* - size_t
* - memcpy
* - grant_ref_t
* These declarations are provided by string.h of the standard headers,
* and grant_table.h from the Xen public headers.
*/

#include <xen/interface/grant_table.h>

typedef unsigned int RING_IDX;

/* Round a 32-bit unsigned constant down to the nearest power of two. */
#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x))
#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x))
#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x))
Expand All @@ -27,82 +59,79 @@ typedef unsigned int RING_IDX;
* A ring contains as many entries as will fit, rounded down to the nearest
* power of two (so we can mask with (size-1) to loop around).
*/
#define __CONST_RING_SIZE(_s, _sz) \
(__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
sizeof(((struct _s##_sring *)0)->ring[0])))

#define __CONST_RING_SIZE(_s, _sz) \
(__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
sizeof(((struct _s##_sring *)0)->ring[0])))
/*
* The same for passing in an actual pointer instead of a name tag.
*/
#define __RING_SIZE(_s, _sz) \
(__RD32(((_sz) - (long)&(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
#define __RING_SIZE(_s, _sz) \
(__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))

/*
* Macros to make the correct C datatypes for a new kind of ring.
*
* To make a new ring datatype, you need to have two message structures,
* let's say struct request, and struct response already defined.
* let's say request_t, and response_t already defined.
*
* In a header where you want the ring datatype declared, you then do:
*
* DEFINE_RING_TYPES(mytag, struct request, struct response);
* DEFINE_RING_TYPES(mytag, request_t, response_t);
*
* These expand out to give you a set of types, as you can see below.
* The most important of these are:
*
* struct mytag_sring - The shared ring.
* struct mytag_front_ring - The 'front' half of the ring.
* struct mytag_back_ring - The 'back' half of the ring.
* mytag_sring_t - The shared ring.
* mytag_front_ring_t - The 'front' half of the ring.
* mytag_back_ring_t - The 'back' half of the ring.
*
* To initialize a ring in your code you need to know the location and size
* of the shared memory area (PAGE_SIZE, for instance). To initialise
* the front half:
*
* struct mytag_front_ring front_ring;
* SHARED_RING_INIT((struct mytag_sring *)shared_page);
* FRONT_RING_INIT(&front_ring, (struct mytag_sring *)shared_page,
* PAGE_SIZE);
* mytag_front_ring_t front_ring;
* SHARED_RING_INIT((mytag_sring_t *)shared_page);
* FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*
* Initializing the back follows similarly (note that only the front
* initializes the shared ring):
*
* struct mytag_back_ring back_ring;
* BACK_RING_INIT(&back_ring, (struct mytag_sring *)shared_page,
* PAGE_SIZE);
* mytag_back_ring_t back_ring;
* BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*/

#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
\
/* Shared ring entry */ \
union __name##_sring_entry { \
__req_t req; \
__rsp_t rsp; \
}; \
\
/* Shared ring page */ \
struct __name##_sring { \
RING_IDX req_prod, req_event; \
RING_IDX rsp_prod, rsp_event; \
uint8_t pad[48]; \
union __name##_sring_entry ring[1]; /* variable-length */ \
}; \
\
/* "Front" end's private variables */ \
struct __name##_front_ring { \
RING_IDX req_prod_pvt; \
RING_IDX rsp_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
}; \
\
/* "Back" end's private variables */ \
struct __name##_back_ring { \
RING_IDX rsp_prod_pvt; \
RING_IDX req_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
};

#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
\
/* Shared ring entry */ \
union __name##_sring_entry { \
__req_t req; \
__rsp_t rsp; \
}; \
\
/* Shared ring page */ \
struct __name##_sring { \
RING_IDX req_prod, req_event; \
RING_IDX rsp_prod, rsp_event; \
uint8_t __pad[48]; \
union __name##_sring_entry ring[1]; /* variable-length */ \
}; \
\
/* "Front" end's private variables */ \
struct __name##_front_ring { \
RING_IDX req_prod_pvt; \
RING_IDX rsp_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
}; \
\
/* "Back" end's private variables */ \
struct __name##_back_ring { \
RING_IDX rsp_prod_pvt; \
RING_IDX req_cons; \
unsigned int nr_ents; \
struct __name##_sring *sring; \
}; \
\
/*
* Macros for manipulating rings.
*
Expand All @@ -119,94 +148,99 @@ struct __name##_back_ring { \
*/

/* Initialising empty rings */
#define SHARED_RING_INIT(_s) do { \
(_s)->req_prod = (_s)->rsp_prod = 0; \
(_s)->req_event = (_s)->rsp_event = 1; \
memset((_s)->pad, 0, sizeof((_s)->pad)); \
#define SHARED_RING_INIT(_s) do { \
(_s)->req_prod = (_s)->rsp_prod = 0; \
(_s)->req_event = (_s)->rsp_event = 1; \
(void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \
} while(0)

#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
(_r)->req_prod_pvt = (_i); \
(_r)->rsp_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
(_r)->req_prod_pvt = (_i); \
(_r)->rsp_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
} while (0)

#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)

#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
(_r)->rsp_prod_pvt = (_i); \
(_r)->req_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
(_r)->rsp_prod_pvt = (_i); \
(_r)->req_cons = (_i); \
(_r)->nr_ents = __RING_SIZE(_s, __size); \
(_r)->sring = (_s); \
} while (0)

#define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size)

/* How big is this ring? */
#define RING_SIZE(_r) \
#define RING_SIZE(_r) \
((_r)->nr_ents)

/* Number of free requests (for use on front side only). */
#define RING_FREE_REQUESTS(_r) \
#define RING_FREE_REQUESTS(_r) \
(RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons))

/* Test if there is an empty slot available on the front ring.
* (This is only meaningful from the front. )
*/
#define RING_FULL(_r) \
#define RING_FULL(_r) \
(RING_FREE_REQUESTS(_r) == 0)

/* Test if there are outstanding messages to be processed on a ring. */
#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
((_r)->sring->rsp_prod - (_r)->rsp_cons)

#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
({ \
unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
unsigned int rsp = RING_SIZE(_r) - \
((_r)->req_cons - (_r)->rsp_prod_pvt); \
req < rsp ? req : rsp; \
})
#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \
unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
unsigned int rsp = RING_SIZE(_r) - \
((_r)->req_cons - (_r)->rsp_prod_pvt); \
req < rsp ? req : rsp; \
})

/* Direct access to individual ring elements, by index. */
#define RING_GET_REQUEST(_r, _idx) \
#define RING_GET_REQUEST(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))

#define RING_GET_RESPONSE(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))

/*
* Get a local copy of a request.
* Get a local copy of a request/response.
*
* Use this in preference to RING_GET_REQUEST() so all processing is
* Use this in preference to RING_GET_{REQUEST,RESPONSE}() so all processing is
* done on a local copy that cannot be modified by the other end.
*
* Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this
* to be ineffective where _req is a struct which consists of only bitfields.
* to be ineffective where dest is a struct which consists of only bitfields.
*/
#define RING_COPY_REQUEST(_r, _idx, _req) do { \
/* Use volatile to force the copy into _req. */ \
*(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \
#define RING_COPY_(type, r, idx, dest) do { \
/* Use volatile to force the copy into dest. */ \
*(dest) = *(volatile typeof(dest))RING_GET_##type(r, idx); \
} while (0)

#define RING_GET_RESPONSE(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
#define RING_COPY_REQUEST(r, idx, req) RING_COPY_(REQUEST, r, idx, req)
#define RING_COPY_RESPONSE(r, idx, rsp) RING_COPY_(RESPONSE, r, idx, rsp)

/* Loop termination condition: Would the specified index overflow the ring? */
#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))

/* Ill-behaved frontend determination: Can there be this many requests? */
#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
(((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))

/* Ill-behaved backend determination: Can there be this many responses? */
#define RING_RESPONSE_PROD_OVERFLOW(_r, _prod) \
(((_prod) - (_r)->rsp_cons) > RING_SIZE(_r))

#define RING_PUSH_REQUESTS(_r) do { \
virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
#define RING_PUSH_REQUESTS(_r) do { \
virt_wmb(); /* back sees requests /before/ updated producer index */\
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
} while (0)

#define RING_PUSH_RESPONSES(_r) do { \
virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
#define RING_PUSH_RESPONSES(_r) do { \
virt_wmb(); /* front sees resps /before/ updated producer index */ \
(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
} while (0)

/*
Expand Down Expand Up @@ -239,40 +273,40 @@ struct __name##_back_ring { \
* field appropriately.
*/

#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->req_prod; \
RING_IDX __new = (_r)->req_prod_pvt; \
virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = __new; \
virt_mb(); /* back sees new requests /before/ we check req_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
(RING_IDX)(__new - __old)); \
#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->req_prod; \
RING_IDX __new = (_r)->req_prod_pvt; \
virt_wmb(); /* back sees requests /before/ updated producer index */\
(_r)->sring->req_prod = __new; \
virt_mb(); /* back sees new requests /before/ we check req_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
(RING_IDX)(__new - __old)); \
} while (0)

#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->rsp_prod; \
RING_IDX __new = (_r)->rsp_prod_pvt; \
virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = __new; \
virt_mb(); /* front sees new responses /before/ we check rsp_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
(RING_IDX)(__new - __old)); \
#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->rsp_prod; \
RING_IDX __new = (_r)->rsp_prod_pvt; \
virt_wmb(); /* front sees resps /before/ updated producer index */ \
(_r)->sring->rsp_prod = __new; \
virt_mb(); /* front sees new resps /before/ we check rsp_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
(RING_IDX)(__new - __old)); \
} while (0)

#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
if (_work_to_do) break; \
(_r)->sring->req_event = (_r)->req_cons + 1; \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
if (_work_to_do) break; \
(_r)->sring->req_event = (_r)->req_cons + 1; \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
} while (0)

#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
if (_work_to_do) break; \
(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
if (_work_to_do) break; \
(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)


Expand Down

0 comments on commit 629a5d8

Please sign in to comment.