dm: vm_event: add sbuf code in dm

The sbuf will be used by DM to send and receive vm_events.

Tracked-On: #8547
Signed-off-by: Wu Zhou <wu.zhou@intel.com>
Reviewed-by: Jian Jun Chen <jian.jun.chen@intel.com>

devicemodel/Makefile

@@ -187,6 +187,7 @@ SRCS += core/cmd_monitor/socket.c
 SRCS += core/cmd_monitor/command.c
 SRCS += core/cmd_monitor/command_handler.c
 SRCS += core/cmd_monitor/cmd_monitor.c
+SRCS += core/sbuf.c
 
 # arch
 SRCS += arch/x86/pm.c

devicemodel/core/sbuf.c

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2018-2023 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm/errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include "sbuf.h"
+#include <errno.h>
+
+static inline uint32_t sbuf_next_ptr(uint32_t pos_arg,
+		uint32_t span, uint32_t scope)
+{
+	uint32_t pos = pos_arg;
+	pos += span;
+	pos = (pos >= scope) ? (pos - scope) : pos;
+	return pos;
+}
+
+uint32_t sbuf_get(struct shared_buf *sbuf, uint8_t *data)
+{
+	const void *from;
+
+	if ((sbuf == NULL) || (data == NULL))
+		return -EINVAL;
+
+	if (sbuf_is_empty(sbuf)) {
+		/* no data available */
+		return 0;
+	}
+
+	from = (void *)sbuf + SBUF_HEAD_SIZE + sbuf->head;
+
+	memcpy(data, from, sbuf->ele_size);
+
+	mb();
+
+	sbuf->head = sbuf_next_ptr(sbuf->head, sbuf->ele_size, sbuf->size);
+
+	return sbuf->ele_size;
+}
+
+int sbuf_clear_buffered(struct shared_buf *sbuf)
+{
+	if (sbuf == NULL)
+		return -EINVAL;
+
+	sbuf->head = sbuf->tail;
+
+	return 0;
+}
+
+/**
+ * The high caller should guarantee each time there must have
+ * sbuf->ele_size data can be write form data.
+ * Caller should provide the max length of the data for safety reason.
+ *
+ * And this function should guarantee execution atomically.
+ *
+ * flag:
+ * If OVERWRITE_EN set, buf can store (ele_num - 1) elements at most.
+ * Should use lock to guarantee that only one read or write at
+ * the same time.
+ * if OVERWRITE_EN not set, buf can store (ele_num - 1) elements
+ * at most. Shouldn't modify the sbuf->head.
+ *
+ * return:
+ * ele_size:	write succeeded.
+ * 0:		no write, buf is full
+ * UINT32_MAX:	failed, sbuf corrupted.
+ */
+uint32_t sbuf_put(struct shared_buf *sbuf, uint8_t *data, uint32_t max_len)
+{
+	uint32_t ele_size = sbuf->ele_size;
+	void *to;
+	uint32_t next_tail;
+	uint32_t ret;
+	bool trigger_overwrite = false;
+
+	next_tail = sbuf_next_ptr(sbuf->tail, ele_size, sbuf->size);
+
+	if ((next_tail == sbuf->head) && ((sbuf->flags & OVERWRITE_EN) == 0U)) {
+		/* if overrun is not enabled, return 0 directly */
+		ret = 0U;
+	} else if (ele_size <= max_len) {
+		if (next_tail == sbuf->head) {
+			/* accumulate overrun count if necessary */
+			sbuf->overrun_cnt += sbuf->flags & OVERRUN_CNT_EN;
+			trigger_overwrite = true;
+		}
+		to = (void *)sbuf + SBUF_HEAD_SIZE + sbuf->tail;
+
+		memcpy(to, data, ele_size);
+		/* make sure write data before update head */
+		mb();
+
+		if (trigger_overwrite) {
+			sbuf->head = sbuf_next_ptr(sbuf->head,
+					ele_size, sbuf->size);
+		}
+		sbuf->tail = next_tail;
+		ret = ele_size;
+	} else {
+		/* there must be something wrong */
+		ret = UINT32_MAX;
+	}
+
+	return ret;
+}
+
+void sbuf_init(struct shared_buf *sbuf, uint32_t total_size, uint32_t ele_size)
+{
+	sbuf->magic = SBUF_MAGIC;
+	sbuf->ele_size = ele_size;
+	sbuf->ele_num = (total_size - SBUF_HEAD_SIZE) / sbuf->ele_size;
+	sbuf->size = sbuf->ele_size * sbuf->ele_num;
+	sbuf->flags = 0;
+	sbuf->overrun_cnt = 0;
+	sbuf->head = 0;
+	sbuf->tail = 0;
+}

devicemodel/include/sbuf.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2018-2023 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SHARED_BUF_H
+#define SHARED_BUF_H
+
+#include <linux/types.h>
+#include "acrn_common.h"
+
+
+static inline bool sbuf_is_empty(struct shared_buf *sbuf)
+{
+	return (sbuf->head == sbuf->tail);
+}
+
+static inline void sbuf_clear_flags(struct shared_buf *sbuf, uint64_t flags)
+{
+        sbuf->flags &= ~flags;
+}
+
+static inline void sbuf_set_flags(struct shared_buf *sbuf, uint64_t flags)
+{
+        sbuf->flags = flags;
+}
+
+static inline void sbuf_add_flags(struct shared_buf *sbuf, uint64_t flags)
+{
+        sbuf->flags |= flags;
+}
+
+uint32_t sbuf_get(struct shared_buf *sbuf, uint8_t *data);
+uint32_t sbuf_put(struct shared_buf *sbuf, uint8_t *data, uint32_t max_len);
+int sbuf_clear_buffered(struct shared_buf *sbuf);
+void sbuf_init(struct shared_buf *sbuf, uint32_t total_size, uint32_t ele_size);
+
+#endif /* SHARED_BUF_H */