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hc
2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/drivers/hv/ring_buffer.c
....@@ -1,25 +1,12 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  *
34  * Copyright (c) 2009, Microsoft Corporation.
4
- *
5
- * This program is free software; you can redistribute it and/or modify it
6
- * under the terms and conditions of the GNU General Public License,
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- * version 2, as published by the Free Software Foundation.
8
- *
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- * This program is distributed in the hope it will be useful, but WITHOUT
10
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12
- * more details.
13
- *
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- * You should have received a copy of the GNU General Public License along with
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- * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
16
- * Place - Suite 330, Boston, MA 02111-1307 USA.
175  *
186  * Authors:
197  *   Haiyang Zhang <haiyangz@microsoft.com>
208  *   Hank Janssen  <hjanssen@microsoft.com>
219  *   K. Y. Srinivasan <kys@microsoft.com>
22
- *
2310  */
2411 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2512 
....@@ -74,8 +61,10 @@
7461 	 * This is the only case we need to signal when the
7562 	 * ring transitions from being empty to non-empty.
7663 	 */
77
-	if (old_write == READ_ONCE(rbi->ring_buffer->read_index))
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+	if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) {
65
+		++channel->intr_out_empty;
7866 		vmbus_setevent(channel);
67
+	}
7968 }
8069 
8170 /* Get the next write location for the specified ring buffer. */
....@@ -164,14 +153,18 @@
164153 }
165154 
166155 /* Get various debug metrics for the specified ring buffer. */
167
-int hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
156
+int hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
168157 				struct hv_ring_buffer_debug_info *debug_info)
169158 {
170159 	u32 bytes_avail_towrite;
171160 	u32 bytes_avail_toread;
172161 
173
-	if (!ring_info->ring_buffer)
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+	mutex_lock(&ring_info->ring_buffer_mutex);
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+
164
+	if (!ring_info->ring_buffer) {
165
+		mutex_unlock(&ring_info->ring_buffer_mutex);
174166 		return -EINVAL;
167
+	}
175168 
176169 	hv_get_ringbuffer_availbytes(ring_info,
177170 				     &bytes_avail_toread,
....@@ -182,9 +175,18 @@
182175 	debug_info->current_write_index = ring_info->ring_buffer->write_index;
183176 	debug_info->current_interrupt_mask
184177 		= ring_info->ring_buffer->interrupt_mask;
178
+	mutex_unlock(&ring_info->ring_buffer_mutex);
179
+
185180 	return 0;
186181 }
187182 EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo);
183
+
184
+/* Initialize a channel's ring buffer info mutex locks */
185
+void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
186
+{
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+	mutex_init(&channel->inbound.ring_buffer_mutex);
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+	mutex_init(&channel->outbound.ring_buffer_mutex);
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+}
188190 
189191 /* Initialize the ring buffer. */
190192 int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
....@@ -194,8 +196,6 @@
194196 	struct page **pages_wraparound;
195197 
196198 	BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));
197
-
198
-	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
199199 
200200 	/*
201201 	 * First page holds struct hv_ring_buffer, do wraparound mapping for
....@@ -230,6 +230,7 @@
230230 		reciprocal_value(ring_info->ring_size / 10);
231231 	ring_info->ring_datasize = ring_info->ring_size -
232232 		sizeof(struct hv_ring_buffer);
233
+	ring_info->priv_read_index = 0;
233234 
234235 	spin_lock_init(&ring_info->ring_lock);
235236 
....@@ -239,7 +240,10 @@
239240 /* Cleanup the ring buffer. */
240241 void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
241242 {
243
+	mutex_lock(&ring_info->ring_buffer_mutex);
242244 	vunmap(ring_info->ring_buffer);
245
+	ring_info->ring_buffer = NULL;
246
+	mutex_unlock(&ring_info->ring_buffer_mutex);
243247 }
244248 
245249 /* Write to the ring buffer. */
....@@ -271,9 +275,18 @@
271275 	 * is empty since the read index == write index.
272276 	 */
273277 	if (bytes_avail_towrite <= totalbytes_towrite) {
278
+		++channel->out_full_total;
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+
280
+		if (!channel->out_full_flag) {
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+			++channel->out_full_first;
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+			channel->out_full_flag = true;
283
+		}
284
+
274285 		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
275286 		return -EAGAIN;
276287 	}
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+
289
+	channel->out_full_flag = false;
277290 
278291 	/* Write to the ring buffer */
279292 	next_write_location = hv_get_next_write_location(outring_info);
....@@ -365,7 +378,16 @@
365378 static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
366379 {
367380 	u32 priv_read_loc = rbi->priv_read_index;
368
-	u32 write_loc = READ_ONCE(rbi->ring_buffer->write_index);
381
+	u32 write_loc;
382
+
383
+	/*
384
+	 * The Hyper-V host writes the packet data, then uses
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+	 * store_release() to update the write_index.  Use load_acquire()
386
+	 * here to prevent loads of the packet data from being re-ordered
387
+	 * before the read of the write_index and potentially getting
388
+	 * stale data.
389
+	 */
390
+	write_loc = virt_load_acquire(&rbi->ring_buffer->write_index);
369391 
370392 	if (write_loc >= priv_read_loc)
371393 		return write_loc - priv_read_loc;
....@@ -383,6 +405,7 @@
383405 	struct hv_ring_buffer_info *rbi = &channel->inbound;
384406 	struct vmpacket_descriptor *desc;
385407 
408
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
386409 	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
387410 		return NULL;
388411 
....@@ -408,6 +431,7 @@
408431 	u32 packetlen = desc->len8 << 3;
409432 	u32 dsize = rbi->ring_datasize;
410433 
434
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
411435 	/* bump offset to next potential packet */
412436 	rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER;
413437 	if (rbi->priv_read_index >= dsize)
....@@ -529,6 +553,7 @@
529553 	if (curr_write_sz <= pending_sz)
530554 		return;
531555 
556
+	++channel->intr_in_full;
532557 	vmbus_setevent(channel);
533558 }
534559 EXPORT_SYMBOL_GPL(hv_pkt_iter_close);