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-rw-r--r--src/include/xen/io/ring.h248
1 files changed, 216 insertions, 32 deletions
diff --git a/src/include/xen/io/ring.h b/src/include/xen/io/ring.h
index 89d73869..41b50e2c 100644
--- a/src/include/xen/io/ring.h
+++ b/src/include/xen/io/ring.h
@@ -1,26 +1,9 @@
+/* SPDX-License-Identifier: MIT */
/******************************************************************************
* 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.
*/
@@ -29,6 +12,21 @@
FILE_LICENCE ( MIT );
+/*
+ * 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-compat.h"
#if __XEN_INTERFACE_VERSION__ < 0x00030208
@@ -82,9 +80,8 @@ typedef unsigned int RING_IDX;
* of the shared memory area (PAGE_SIZE, for instance). To initialise
* the front half:
*
- * 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);
+ * 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):
@@ -113,7 +110,7 @@ struct __name##_sring { \
uint8_t msg; \
} tapif_user; \
uint8_t pvt_pad[4]; \
- } private; \
+ } pvt; \
uint8_t __pad[44]; \
union __name##_sring_entry ring[1]; /* variable-length */ \
}; \
@@ -158,24 +155,33 @@ typedef struct __name##_back_ring __name##_back_ring_t
#define SHARED_RING_INIT(_s) do { \
(_s)->req_prod = (_s)->rsp_prod = 0; \
(_s)->req_event = (_s)->rsp_event = 1; \
- (void)memset((_s)->private.pvt_pad, 0, sizeof((_s)->private.pvt_pad)); \
+ (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \
(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; \
+#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; \
+#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __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, _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) \
((_r)->nr_ents)
@@ -191,11 +197,11 @@ typedef struct __name##_back_ring __name##_back_ring_t
(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)
#ifdef __GNUC__
-#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \
+#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); \
@@ -203,13 +209,27 @@ typedef struct __name##_back_ring __name##_back_ring_t
})
#else
/* Same as above, but without the nice GCC ({ ... }) syntax. */
-#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
+#define XEN_RING_NR_UNCONSUMED_REQUESTS(_r) \
((((_r)->sring->req_prod - (_r)->req_cons) < \
(RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \
((_r)->sring->req_prod - (_r)->req_cons) : \
(RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt)))
#endif
+#ifdef XEN_RING_HAS_UNCONSUMED_IS_BOOL
+/*
+ * These variants should only be used in case no caller is abusing them for
+ * obtaining the number of unconsumed responses/requests.
+ */
+#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
+ (!!XEN_RING_NR_UNCONSUMED_RESPONSES(_r))
+#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
+ (!!XEN_RING_NR_UNCONSUMED_REQUESTS(_r))
+#else
+#define RING_HAS_UNCONSUMED_RESPONSES(_r) XEN_RING_NR_UNCONSUMED_RESPONSES(_r)
+#define RING_HAS_UNCONSUMED_REQUESTS(_r) XEN_RING_NR_UNCONSUMED_REQUESTS(_r)
+#endif
+
/* Direct access to individual ring elements, by index. */
#define RING_GET_REQUEST(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
@@ -217,6 +237,23 @@ typedef struct __name##_back_ring __name##_back_ring_t
#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) \
(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
@@ -225,6 +262,10 @@ typedef struct __name##_back_ring __name##_back_ring_t
#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 { \
xen_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
@@ -301,6 +342,149 @@ typedef struct __name##_back_ring __name##_back_ring_t
(_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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