[RFC PATCH 8/12] x86/Hyper-V: Initialize bounce buffer page cache and list

@@ -8,6 +8,6 @@ CFLAGS_hv_balloon.o = -I$(src)
 
 hv_vmbus-y := vmbus_drv.o \
 		 hv.o connection.o channel.o \
-		 channel_mgmt.o ring_buffer.o hv_trace.o
+		 channel_mgmt.o ring_buffer.o hv_trace.o hv_bounce.o
 hv_vmbus-$(CONFIG_HYPERV_TESTING)	+= hv_debugfs.o
 hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_fcopy.o hv_utils_transport.o

@@ -336,6 +336,18 @@ bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, u8 *buf,
 
 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
 
+/*
+ * free_channel - Release the resources used by the vmbus channel object
+ */
+static void free_channel(struct vmbus_channel *channel)
+{
+	tasklet_kill(&channel->callback_event);
+	vmbus_remove_channel_attr_group(channel);
+
+	kobject_put(&channel->kobj);
+	hv_free_channel_ivm(channel);
+}
+
 /*
  * alloc_channel - Allocate and initialize a vmbus channel object
  */

@@ -360,17 +372,6 @@ static struct vmbus_channel *alloc_channel(void)
 	return channel;
 }
 
-/*
- * free_channel - Release the resources used by the vmbus channel object
- */
-static void free_channel(struct vmbus_channel *channel)
-{
-	tasklet_kill(&channel->callback_event);
-	vmbus_remove_channel_attr_group(channel);
-
-	kobject_put(&channel->kobj);
-}
-
 void vmbus_channel_map_relid(struct vmbus_channel *channel)
 {
 	if (WARN_ON(channel->offermsg.child_relid >= MAX_CHANNEL_RELIDS))

@@ -510,6 +511,8 @@ static void vmbus_add_channel_work(struct work_struct *work)
 		if (vmbus_add_channel_kobj(dev, newchannel))
 			goto err_deq_chan;
 
+		hv_init_channel_ivm(newchannel);
+
 		if (primary_channel->sc_creation_callback != NULL)
 			primary_channel->sc_creation_callback(newchannel);
 

@@ -543,6 +546,10 @@ static void vmbus_add_channel_work(struct work_struct *work)
 	}
 
 	newchannel->probe_done = true;
+
+	if (hv_init_channel_ivm(newchannel))
+		goto err_deq_chan;
+
 	return;
 
 err_deq_chan:

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Bounce buffer code for Hyper-V Isolation VM support.
+ *
+ * Authors:
+ *   Sunil Muthuswamy <sunilmut@microsoft.com>
+ *   Tianyu Lan <Tianyu.Lan@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include "hyperv_vmbus.h"
+
+int hv_init_channel_ivm(struct vmbus_channel *channel)
+{
+	if (!hv_is_isolation_supported())
+		return 0;
+
+	INIT_LIST_HEAD(&channel->bounce_page_free_head);
+	INIT_LIST_HEAD(&channel->bounce_pkt_free_list_head);
+
+	channel->bounce_pkt_cache = KMEM_CACHE(hv_bounce_pkt, 0);
+	if (unlikely(!channel->bounce_pkt_cache))
+		return -ENOMEM;
+	channel->bounce_page_cache = KMEM_CACHE(hv_bounce_page_list, 0);
+	if (unlikely(!channel->bounce_page_cache))
+		return -ENOMEM;
+
+	return 0;
+}
+
+void hv_free_channel_ivm(struct vmbus_channel *channel)
+{
+	if (!hv_is_isolation_supported())
+		return;
+
+
+	cancel_delayed_work_sync(&channel->bounce_page_list_maintain);
+	hv_bounce_pkt_list_free(channel, &channel->bounce_pkt_free_list_head);
+	hv_bounce_page_list_free(channel, &channel->bounce_page_free_head);
+	kmem_cache_destroy(channel->bounce_pkt_cache);
+	kmem_cache_destroy(channel->bounce_page_cache);
+}

@@ -19,6 +19,7 @@
 #include <linux/hyperv.h>
 #include <linux/interrupt.h>
 
+#include <asm/mshyperv.h>
 #include "hv_trace.h"
 
 /*

@@ -56,6 +57,19 @@ union hv_monitor_trigger_state {
 	};
 };
 
+/*
+ * All vmbus channels initially start with zero bounce pages and are required
+ * to set any non-zero size, if needed.
+ */
+#define HV_DEFAULT_BOUNCE_BUFFER_PAGES  0
+
+/* MIN should be a power of 2 */
+#define HV_MIN_BOUNCE_BUFFER_PAGES	64
+
+extern int hv_init_channel_ivm(struct vmbus_channel *channel);
+
+extern void hv_free_channel_ivm(struct vmbus_channel *channel);
+
 /* struct hv_monitor_page Layout */
 /* ------------------------------------------------------ */
 /* | 0   | TriggerState (4 bytes) | Rsvd1 (4 bytes)     | */

@@ -25,6 +25,9 @@
 #include <linux/interrupt.h>
 #include <linux/reciprocal_div.h>
 #include <asm/hyperv-tlfs.h>
+#include <linux/slab.h>
+#include <linux/mempool.h>
+#include <linux/mempool.h>
 
 #define MAX_PAGE_BUFFER_COUNT				32
 #define MAX_MULTIPAGE_BUFFER_COUNT			32 /* 128K */

@@ -1007,9 +1010,28 @@ struct vmbus_channel {
 	u32 fuzz_testing_interrupt_delay;
 	u32 fuzz_testing_message_delay;
 
+
 	/* request/transaction ids for VMBus */
 	struct vmbus_requestor requestor;
 	u32 rqstor_size;
+	/*
+	 * Minimum number of bounce resources (i.e bounce packets & pages) that
+	 * should be allocated and reserved for this channel. Allocation is
+	 * permitted to go beyond this limit, and the maintenance task takes
+	 * care of releasing the extra allocated resources.
+	 */
+	u32 min_bounce_resource_count;
+
+	/* The free list of bounce pages is LRU sorted based on last used */
+	struct list_head bounce_page_free_head;
+	u32 bounce_page_alloc_count;
+	struct delayed_work bounce_page_list_maintain;
+
+	struct kmem_cache *bounce_page_cache;
+	struct kmem_cache *bounce_pkt_cache;
+	struct list_head bounce_pkt_free_list_head;
+	u32 bounce_pkt_free_count;
+	spinlock_t bp_lock;
 };
 
 u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr);