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-rw-r--r--include/xen/interface/io/ring.h430
1 files changed, 305 insertions, 125 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 75271b9a8f61..4fef1efcdcab 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: MIT */
/******************************************************************************
* ring.h
*
@@ -9,10 +10,27 @@
#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))
@@ -24,82 +42,78 @@ 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 ring;
+ * XEN_FRONT_RING_INIT(&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[]; \
+}; \
+ \
+/* "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.
*
@@ -116,86 +130,109 @@ 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_INIT(_r, _s, __size) do { \
- (_r)->req_prod_pvt = 0; \
- (_r)->rsp_cons = 0; \
- (_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 BACK_RING_INIT(_r, _s, __size) do { \
- (_r)->rsp_prod_pvt = 0; \
- (_r)->req_cons = 0; \
- (_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)
-/* Initialize to existing shared indexes -- for recovery */
-#define FRONT_RING_ATTACH(_r, _s, __size) do { \
- (_r)->sring = (_s); \
- (_r)->req_prod_pvt = (_s)->req_prod; \
- (_r)->rsp_cons = (_s)->rsp_prod; \
- (_r)->nr_ents = __RING_SIZE(_s, __size); \
+#define XEN_FRONT_RING_INIT(r, s, size) do { \
+ SHARED_RING_INIT(s); \
+ FRONT_RING_INIT(r, s, size); \
} while (0)
-#define BACK_RING_ATTACH(_r, _s, __size) do { \
- (_r)->sring = (_s); \
- (_r)->rsp_prod_pvt = (_s)->rsp_prod; \
- (_r)->req_cons = (_s)->req_prod; \
- (_r)->nr_ents = __RING_SIZE(_s, __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); \
} 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 XEN_RING_NR_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 XEN_RING_NR_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_RESPONSES(_r) \
+ (!!XEN_RING_NR_UNCONSUMED_RESPONSES(_r))
+#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
+ (!!XEN_RING_NR_UNCONSUMED_REQUESTS(_r))
/* 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) \
+#define RING_GET_RESPONSE(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
+/*
+ * Get a local copy of a request/response.
+ *
+ * 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 dest is a struct which consists of only bitfields.
+ */
+#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_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))
-#define RING_PUSH_REQUESTS(_r) do { \
- wmb(); /* back sees requests /before/ updated producer index */ \
- (_r)->sring->req_prod = (_r)->req_prod_pvt; \
+/* Ill-behaved frontend determination: Can there be this many requests? */
+#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; \
} while (0)
-#define RING_PUSH_RESPONSES(_r) do { \
- 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)
/*
@@ -228,40 +265,183 @@ 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; \
- wmb(); /* back sees requests /before/ updated producer index */ \
- (_r)->sring->req_prod = __new; \
- 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; \
- wmb(); /* front sees responses /before/ updated producer index */ \
- (_r)->sring->rsp_prod = __new; \
- 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; \
- 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; \
- 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)
+
+/*
+ * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and
+ * functions to check if there is data on the ring, and to read and
+ * write to them.
+ *
+ * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but
+ * does not define the indexes page. As different protocols can have
+ * extensions to the basic format, this macro allow them to define their
+ * own struct.
+ *
+ * XEN_FLEX_RING_SIZE
+ * Convenience macro to calculate the size of one of the two rings
+ * from the overall order.
+ *
+ * $NAME_mask
+ * Function to apply the size mask to an index, to reduce the index
+ * within the range [0-size].
+ *
+ * $NAME_read_packet
+ * Function to read data from the ring. The amount of data to read is
+ * specified by the "size" argument.
+ *
+ * $NAME_write_packet
+ * Function to write data to the ring. The amount of data to write is
+ * specified by the "size" argument.
+ *
+ * $NAME_get_ring_ptr
+ * Convenience function that returns a pointer to read/write to the
+ * ring at the right location.
+ *
+ * $NAME_data_intf
+ * Indexes page, shared between frontend and backend. It also
+ * contains the array of grant refs.
+ *
+ * $NAME_queued
+ * Function to calculate how many bytes are currently on the ring,
+ * ready to be read. It can also be used to calculate how much free
+ * space is currently on the ring (XEN_FLEX_RING_SIZE() -
+ * $NAME_queued()).
+ */
+
+#ifndef XEN_PAGE_SHIFT
+/* The PAGE_SIZE for ring protocols and hypercall interfaces is always
+ * 4K, regardless of the architecture, and page granularity chosen by
+ * operating systems.
+ */
+#define XEN_PAGE_SHIFT 12
+#endif
+#define XEN_FLEX_RING_SIZE(order) \
+ (1UL << ((order) + XEN_PAGE_SHIFT - 1))
+
+#define DEFINE_XEN_FLEX_RING(name) \
+static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \
+{ \
+ return idx & (ring_size - 1); \
+} \
+ \
+static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \
+ RING_IDX idx, \
+ RING_IDX ring_size) \
+{ \
+ return buf + name##_mask(idx, ring_size); \
+} \
+ \
+static inline void name##_read_packet(void *opaque, \
+ const unsigned char *buf, \
+ size_t size, \
+ RING_IDX masked_prod, \
+ RING_IDX *masked_cons, \
+ RING_IDX ring_size) \
+{ \
+ if (*masked_cons < masked_prod || \
+ size <= ring_size - *masked_cons) { \
+ memcpy(opaque, buf + *masked_cons, size); \
+ } else { \
+ memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \
+ memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \
+ size - (ring_size - *masked_cons)); \
+ } \
+ *masked_cons = name##_mask(*masked_cons + size, ring_size); \
+} \
+ \
+static inline void name##_write_packet(unsigned char *buf, \
+ const void *opaque, \
+ size_t size, \
+ RING_IDX *masked_prod, \
+ RING_IDX masked_cons, \
+ RING_IDX ring_size) \
+{ \
+ if (*masked_prod < masked_cons || \
+ size <= ring_size - *masked_prod) { \
+ memcpy(buf + *masked_prod, opaque, size); \
+ } else { \
+ memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \
+ memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \
+ size - (ring_size - *masked_prod)); \
+ } \
+ *masked_prod = name##_mask(*masked_prod + size, ring_size); \
+} \
+ \
+static inline RING_IDX name##_queued(RING_IDX prod, \
+ RING_IDX cons, \
+ RING_IDX ring_size) \
+{ \
+ RING_IDX size; \
+ \
+ if (prod == cons) \
+ return 0; \
+ \
+ prod = name##_mask(prod, ring_size); \
+ cons = name##_mask(cons, ring_size); \
+ \
+ if (prod == cons) \
+ return ring_size; \
+ \
+ if (prod > cons) \
+ size = prod - cons; \
+ else \
+ size = ring_size - (cons - prod); \
+ return size; \
+} \
+ \
+struct name##_data { \
+ unsigned char *in; /* half of the allocation */ \
+ unsigned char *out; /* half of the allocation */ \
+}
+
+#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \
+struct name##_data_intf { \
+ RING_IDX in_cons, in_prod; \
+ \
+ uint8_t pad1[56]; \
+ \
+ RING_IDX out_cons, out_prod; \
+ \
+ uint8_t pad2[56]; \
+ \
+ RING_IDX ring_order; \
+ grant_ref_t ref[]; \
+}; \
+DEFINE_XEN_FLEX_RING(name)
+
#endif /* __XEN_PUBLIC_IO_RING_H__ */
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