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9e2b3e834c
Commit b24413180f ("License cleanup: add SPDX GPL-2.0 license
identifier to files with no license") was meant to do a tree-wide
cleanup for files without any license information by adding a SPDX
GPL-2.0 line to them.
Unfortunately this was applied even to several Xen-related headers
which have been originally under the MIT license, but obviously have
been copied to the Linux tree from the Xen project without keeping the
license boiler plate as required.
Correct that by changing the license of those files back to "MIT".
Some files still contain the MIT license text. Replace that by the
related SPDX line.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20211015143312.29900-1-jgross@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
439 lines
22 KiB
C
439 lines
22 KiB
C
/* SPDX-License-Identifier: MIT */
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/******************************************************************************
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* ring.h
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*
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* Shared producer-consumer ring macros.
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*
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* Tim Deegan and Andrew Warfield November 2004.
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*/
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#ifndef __XEN_PUBLIC_IO_RING_H__
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#define __XEN_PUBLIC_IO_RING_H__
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/*
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* When #include'ing this header, you need to provide the following
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* declaration upfront:
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* - standard integers types (uint8_t, uint16_t, etc)
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* They are provided by stdint.h of the standard headers.
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*
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* In addition, if you intend to use the FLEX macros, you also need to
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* provide the following, before invoking the FLEX macros:
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* - size_t
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* - memcpy
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* - grant_ref_t
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* These declarations are provided by string.h of the standard headers,
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* and grant_table.h from the Xen public headers.
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*/
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#include <xen/interface/grant_table.h>
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typedef unsigned int RING_IDX;
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/* Round a 32-bit unsigned constant down to the nearest power of two. */
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#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
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#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x))
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#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x))
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#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x))
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#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x))
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/*
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* Calculate size of a shared ring, given the total available space for the
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* ring and indexes (_sz), and the name tag of the request/response structure.
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* A ring contains as many entries as will fit, rounded down to the nearest
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* power of two (so we can mask with (size-1) to loop around).
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*/
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#define __CONST_RING_SIZE(_s, _sz) \
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(__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
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sizeof(((struct _s##_sring *)0)->ring[0])))
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/*
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* The same for passing in an actual pointer instead of a name tag.
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*/
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#define __RING_SIZE(_s, _sz) \
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(__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
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/*
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* Macros to make the correct C datatypes for a new kind of ring.
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*
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* To make a new ring datatype, you need to have two message structures,
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* let's say request_t, and response_t already defined.
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*
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* In a header where you want the ring datatype declared, you then do:
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*
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* DEFINE_RING_TYPES(mytag, request_t, response_t);
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*
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* These expand out to give you a set of types, as you can see below.
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* The most important of these are:
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*
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* mytag_sring_t - The shared ring.
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* mytag_front_ring_t - The 'front' half of the ring.
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* mytag_back_ring_t - The 'back' half of the ring.
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*
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* To initialize a ring in your code you need to know the location and size
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* of the shared memory area (PAGE_SIZE, for instance). To initialise
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* the front half:
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*
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* mytag_front_ring_t front_ring;
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* SHARED_RING_INIT((mytag_sring_t *)shared_page);
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* FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
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*
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* Initializing the back follows similarly (note that only the front
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* initializes the shared ring):
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*
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* mytag_back_ring_t back_ring;
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* BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
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*/
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#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
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\
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/* Shared ring entry */ \
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union __name##_sring_entry { \
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__req_t req; \
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__rsp_t rsp; \
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}; \
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\
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/* Shared ring page */ \
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struct __name##_sring { \
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RING_IDX req_prod, req_event; \
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RING_IDX rsp_prod, rsp_event; \
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uint8_t __pad[48]; \
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union __name##_sring_entry ring[1]; /* variable-length */ \
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}; \
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\
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/* "Front" end's private variables */ \
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struct __name##_front_ring { \
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RING_IDX req_prod_pvt; \
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RING_IDX rsp_cons; \
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unsigned int nr_ents; \
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struct __name##_sring *sring; \
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}; \
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\
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/* "Back" end's private variables */ \
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struct __name##_back_ring { \
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RING_IDX rsp_prod_pvt; \
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RING_IDX req_cons; \
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unsigned int nr_ents; \
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struct __name##_sring *sring; \
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}; \
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\
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/*
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* Macros for manipulating rings.
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*
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* FRONT_RING_whatever works on the "front end" of a ring: here
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* requests are pushed on to the ring and responses taken off it.
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*
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* BACK_RING_whatever works on the "back end" of a ring: here
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* requests are taken off the ring and responses put on.
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*
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* N.B. these macros do NO INTERLOCKS OR FLOW CONTROL.
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* This is OK in 1-for-1 request-response situations where the
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* requestor (front end) never has more than RING_SIZE()-1
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* outstanding requests.
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*/
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/* Initialising empty rings */
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#define SHARED_RING_INIT(_s) do { \
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(_s)->req_prod = (_s)->rsp_prod = 0; \
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(_s)->req_event = (_s)->rsp_event = 1; \
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(void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \
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} while(0)
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#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
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(_r)->req_prod_pvt = (_i); \
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(_r)->rsp_cons = (_i); \
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(_r)->nr_ents = __RING_SIZE(_s, __size); \
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(_r)->sring = (_s); \
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} while (0)
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#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
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#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
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(_r)->rsp_prod_pvt = (_i); \
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(_r)->req_cons = (_i); \
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(_r)->nr_ents = __RING_SIZE(_s, __size); \
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(_r)->sring = (_s); \
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} while (0)
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#define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size)
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/* How big is this ring? */
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#define RING_SIZE(_r) \
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((_r)->nr_ents)
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/* Number of free requests (for use on front side only). */
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#define RING_FREE_REQUESTS(_r) \
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(RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons))
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/* Test if there is an empty slot available on the front ring.
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* (This is only meaningful from the front. )
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*/
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#define RING_FULL(_r) \
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(RING_FREE_REQUESTS(_r) == 0)
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/* Test if there are outstanding messages to be processed on a ring. */
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#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
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((_r)->sring->rsp_prod - (_r)->rsp_cons)
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#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \
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unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
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unsigned int rsp = RING_SIZE(_r) - \
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((_r)->req_cons - (_r)->rsp_prod_pvt); \
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req < rsp ? req : rsp; \
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})
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/* Direct access to individual ring elements, by index. */
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#define RING_GET_REQUEST(_r, _idx) \
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(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
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#define RING_GET_RESPONSE(_r, _idx) \
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(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
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/*
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* Get a local copy of a request/response.
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*
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* Use this in preference to RING_GET_{REQUEST,RESPONSE}() so all processing is
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* done on a local copy that cannot be modified by the other end.
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*
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* Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this
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* to be ineffective where dest is a struct which consists of only bitfields.
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*/
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#define RING_COPY_(type, r, idx, dest) do { \
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/* Use volatile to force the copy into dest. */ \
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*(dest) = *(volatile typeof(dest))RING_GET_##type(r, idx); \
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} while (0)
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#define RING_COPY_REQUEST(r, idx, req) RING_COPY_(REQUEST, r, idx, req)
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#define RING_COPY_RESPONSE(r, idx, rsp) RING_COPY_(RESPONSE, r, idx, rsp)
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/* Loop termination condition: Would the specified index overflow the ring? */
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#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
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(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
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/* Ill-behaved frontend determination: Can there be this many requests? */
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#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
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(((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
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/* Ill-behaved backend determination: Can there be this many responses? */
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#define RING_RESPONSE_PROD_OVERFLOW(_r, _prod) \
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(((_prod) - (_r)->rsp_cons) > RING_SIZE(_r))
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#define RING_PUSH_REQUESTS(_r) do { \
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virt_wmb(); /* back sees requests /before/ updated producer index */\
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(_r)->sring->req_prod = (_r)->req_prod_pvt; \
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} while (0)
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#define RING_PUSH_RESPONSES(_r) do { \
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virt_wmb(); /* front sees resps /before/ updated producer index */ \
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(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
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} while (0)
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/*
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* Notification hold-off (req_event and rsp_event):
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*
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* When queueing requests or responses on a shared ring, it may not always be
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* necessary to notify the remote end. For example, if requests are in flight
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* in a backend, the front may be able to queue further requests without
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* notifying the back (if the back checks for new requests when it queues
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* responses).
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*
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* When enqueuing requests or responses:
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*
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* Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument
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* is a boolean return value. True indicates that the receiver requires an
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* asynchronous notification.
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*
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* After dequeuing requests or responses (before sleeping the connection):
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*
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* Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES().
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* The second argument is a boolean return value. True indicates that there
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* are pending messages on the ring (i.e., the connection should not be put
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* to sleep).
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*
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* These macros will set the req_event/rsp_event field to trigger a
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* notification on the very next message that is enqueued. If you want to
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* create batches of work (i.e., only receive a notification after several
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* messages have been enqueued) then you will need to create a customised
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* version of the FINAL_CHECK macro in your own code, which sets the event
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* field appropriately.
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*/
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#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
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RING_IDX __old = (_r)->sring->req_prod; \
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RING_IDX __new = (_r)->req_prod_pvt; \
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virt_wmb(); /* back sees requests /before/ updated producer index */\
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(_r)->sring->req_prod = __new; \
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virt_mb(); /* back sees new requests /before/ we check req_event */ \
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(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
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(RING_IDX)(__new - __old)); \
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} while (0)
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#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
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RING_IDX __old = (_r)->sring->rsp_prod; \
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RING_IDX __new = (_r)->rsp_prod_pvt; \
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virt_wmb(); /* front sees resps /before/ updated producer index */ \
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(_r)->sring->rsp_prod = __new; \
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virt_mb(); /* front sees new resps /before/ we check rsp_event */ \
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(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
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(RING_IDX)(__new - __old)); \
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} while (0)
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#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
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(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
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if (_work_to_do) break; \
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(_r)->sring->req_event = (_r)->req_cons + 1; \
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virt_mb(); \
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(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
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} while (0)
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#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
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(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
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if (_work_to_do) break; \
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(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
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virt_mb(); \
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(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
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} while (0)
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/*
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* DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and
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* functions to check if there is data on the ring, and to read and
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* write to them.
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*
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* DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but
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* does not define the indexes page. As different protocols can have
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* extensions to the basic format, this macro allow them to define their
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* own struct.
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*
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* XEN_FLEX_RING_SIZE
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* Convenience macro to calculate the size of one of the two rings
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* from the overall order.
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*
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* $NAME_mask
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* Function to apply the size mask to an index, to reduce the index
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* within the range [0-size].
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*
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* $NAME_read_packet
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* Function to read data from the ring. The amount of data to read is
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* specified by the "size" argument.
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*
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* $NAME_write_packet
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* Function to write data to the ring. The amount of data to write is
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* specified by the "size" argument.
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*
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* $NAME_get_ring_ptr
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* Convenience function that returns a pointer to read/write to the
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* ring at the right location.
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*
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* $NAME_data_intf
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* Indexes page, shared between frontend and backend. It also
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* contains the array of grant refs.
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*
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* $NAME_queued
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* Function to calculate how many bytes are currently on the ring,
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* ready to be read. It can also be used to calculate how much free
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* space is currently on the ring (XEN_FLEX_RING_SIZE() -
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* $NAME_queued()).
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*/
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#ifndef XEN_PAGE_SHIFT
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/* The PAGE_SIZE for ring protocols and hypercall interfaces is always
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* 4K, regardless of the architecture, and page granularity chosen by
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* operating systems.
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*/
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#define XEN_PAGE_SHIFT 12
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#endif
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#define XEN_FLEX_RING_SIZE(order) \
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(1UL << ((order) + XEN_PAGE_SHIFT - 1))
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#define DEFINE_XEN_FLEX_RING(name) \
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static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \
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{ \
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return idx & (ring_size - 1); \
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} \
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\
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static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \
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RING_IDX idx, \
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RING_IDX ring_size) \
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{ \
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return buf + name##_mask(idx, ring_size); \
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} \
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\
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static inline void name##_read_packet(void *opaque, \
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const unsigned char *buf, \
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size_t size, \
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RING_IDX masked_prod, \
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RING_IDX *masked_cons, \
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RING_IDX ring_size) \
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{ \
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if (*masked_cons < masked_prod || \
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size <= ring_size - *masked_cons) { \
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memcpy(opaque, buf + *masked_cons, size); \
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} else { \
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memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \
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memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \
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size - (ring_size - *masked_cons)); \
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} \
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*masked_cons = name##_mask(*masked_cons + size, ring_size); \
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} \
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\
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static inline void name##_write_packet(unsigned char *buf, \
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const void *opaque, \
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size_t size, \
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RING_IDX *masked_prod, \
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RING_IDX masked_cons, \
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RING_IDX ring_size) \
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{ \
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if (*masked_prod < masked_cons || \
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size <= ring_size - *masked_prod) { \
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memcpy(buf + *masked_prod, opaque, size); \
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} else { \
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memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \
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memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \
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size - (ring_size - *masked_prod)); \
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} \
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*masked_prod = name##_mask(*masked_prod + size, ring_size); \
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} \
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\
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static inline RING_IDX name##_queued(RING_IDX prod, \
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RING_IDX cons, \
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RING_IDX ring_size) \
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{ \
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RING_IDX size; \
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\
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if (prod == cons) \
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return 0; \
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\
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prod = name##_mask(prod, ring_size); \
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cons = name##_mask(cons, ring_size); \
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\
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if (prod == cons) \
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return ring_size; \
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\
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if (prod > cons) \
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size = prod - cons; \
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else \
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size = ring_size - (cons - prod); \
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return size; \
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} \
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\
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struct name##_data { \
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unsigned char *in; /* half of the allocation */ \
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unsigned char *out; /* half of the allocation */ \
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}
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#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \
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struct name##_data_intf { \
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RING_IDX in_cons, in_prod; \
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\
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uint8_t pad1[56]; \
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\
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RING_IDX out_cons, out_prod; \
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\
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uint8_t pad2[56]; \
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\
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RING_IDX ring_order; \
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grant_ref_t ref[]; \
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}; \
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DEFINE_XEN_FLEX_RING(name)
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|
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#endif /* __XEN_PUBLIC_IO_RING_H__ */
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