diff options
Diffstat (limited to 'include/xen/interface/io/ring.h')
| -rw-r--r-- | include/xen/interface/io/ring.h | 278 |
1 files changed, 156 insertions, 122 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 2af7a1cd6658..b39cdbc522ec 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -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)) @@ -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. * @@ -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) /* @@ -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) |