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Date:   Tue, 20 Aug 2019 19:39:02 -0400
From:   Branden Bonaby <brandonbonaby94@gmail.com>
To:     kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com,
        sashal@kernel.org
Cc:     Branden Bonaby <brandonbonaby94@gmail.com>,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/3] drivers: hv: vmbus: Introduce latency testing
Message-ID: <ebca54bf70d2af53de419c1b7ac8db5b77b888cb.1566340843.git.brandonbonaby94@gmail.com>
References: <cover.1566340843.git.brandonbonaby94@gmail.com>
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Introduce user specified latency in the packet reception path.

Signed-off-by: Branden Bonaby <brandonbonaby94@gmail.com>
---
Changes in v2:
 - Add #ifdef in Kconfig file so test code will not interfere
   with non-test code.
 - Move test code functions for delay to hyperv_vmbus header
   file.
 - Wrap test code under #ifdef statement. 

 drivers/hv/Kconfig        |  7 +++++++
 drivers/hv/connection.c   |  3 +++
 drivers/hv/hyperv_vmbus.h | 20 ++++++++++++++++++++
 drivers/hv/ring_buffer.c  |  7 +++++++
 include/linux/hyperv.h    | 21 +++++++++++++++++++++
 5 files changed, 58 insertions(+)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 9a59957922d4..d97437ba0626 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -29,4 +29,11 @@ config HYPERV_BALLOON
 	help
 	  Select this option to enable Hyper-V Balloon driver.
 
+config HYPERV_TESTING
+        bool "Hyper-V testing"
+        default n
+        depends on HYPERV && DEBUG_FS
+        help
+          Select this option to enable Hyper-V vmbus testing.
+
 endmenu
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 09829e15d4a0..c9c63a4033cd 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -357,6 +357,9 @@ void vmbus_on_event(unsigned long data)
 
 	trace_vmbus_on_event(channel);
 
+#ifdef CONFIG_HYPERV_TESTING
+	hv_debug_delay_test(channel, INTERRUPT_DELAY);
+#endif /* CONFIG_HYPERV_TESTING */
 	do {
 		void (*callback_fn)(void *);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 362e70e9d145..edf14f596d8c 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -357,4 +357,24 @@ enum hvutil_device_state {
 	HVUTIL_DEVICE_DYING,     /* driver unload is in progress */
 };
 
+#ifdef CONFIG_HYPERV_TESTING
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#define TESTING "hyperv"
+
+enum delay {
+	INTERRUPT_DELAY	= 0,
+	MESSAGE_DELAY   = 1,
+};
+
+int hv_debug_delay_files(struct hv_device *dev, struct dentry *root);
+int hv_debug_add_dev_dir(struct hv_device *dev);
+void hv_debug_rm_dev_dir(struct hv_device *dev);
+void hv_debug_rm_all_dir(void);
+void hv_debug_set_dir_dentry(struct hv_device *dev, struct dentry *root);
+void hv_debug_delay_test(struct vmbus_channel *channel, enum delay delay_type);
+
+#endif /* CONFIG_HYPERV_TESTING */
+
 #endif /* _HYPERV_VMBUS_H */
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 9a03b163cbbd..51adda23b398 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -396,6 +396,10 @@ struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
 	struct vmpacket_descriptor *desc;
 
+#ifdef CONFIG_HYPERV_TESTING
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
+#endif /* CONFIG_HYPERV_TESTING */
+
 	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
 		return NULL;
 
@@ -421,6 +425,9 @@ __hv_pkt_iter_next(struct vmbus_channel *channel,
 	u32 packetlen = desc->len8 << 3;
 	u32 dsize = rbi->ring_datasize;
 
+#ifdef CONFIG_HYPERV_TESTING
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
+#endif /* CONFIG_HYPERV_TESTING */
 	/* bump offset to next potential packet */
 	rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER;
 	if (rbi->priv_read_index >= dsize)
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 6256cc34c4a6..6bf8ef5c780c 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -926,6 +926,21 @@ struct vmbus_channel {
 	 * full outbound ring buffer.
 	 */
 	u64 out_full_first;
+
+#ifdef CONFIG_HYPERV_TESTING
+	/* enabling/disabling fuzz testing on the channel (default is false)*/
+	bool fuzz_testing_state;
+
+	/* Interrupt delay will delay the guest from emptying the ring buffer
+	 * for a specific amount of time. The delay is in microseconds and will
+	 * be between 1 to a maximum of 1000, its default is 0 (no delay).
+	 * The  Message delay will delay guest reading on a per message basis
+	 * in microseconds between 1 to 1000 with the default being 0
+	 * (no delay).
+	 */
+	u32 fuzz_testing_interrupt_delay;
+	u32 fuzz_testing_message_delay;
+#endif /* CONFIG_HYPERV_TESTING */
 };
 
 static inline bool is_hvsock_channel(const struct vmbus_channel *c)
@@ -1166,6 +1181,12 @@ struct hv_device {
 
 	struct vmbus_channel *channel;
 	struct kset	     *channels_kset;
+
+#ifdef CONFIG_HYPERV_TESTING
+	/* place holder to keep track of the dir for hv device in debugfs */
+	struct dentry *debug_dir;
+#endif /* CONFIG_HYPERV_TESTING */
+
 };
 
 
-- 
2.17.1