[PATCH 2/2] Drivers: hv: vmbus: suppress some "hv_vmbus: Unknown GUID" warnings

[kys@exchange.microsoft.com]

From: Dexuan Cui <decui@microsoft.com>

Some VMBus devices are not needed by Linux guest[1][2], and, VMBus channels
of Hyper-V Sockets don't really mean usual synthetic devices, so let's
suppress the warnings for them.

[1] https://support.microsoft.com/en-us/kb/2925727
[2] https://msdn.microsoft.com/en-us/library/jj980180(v=winembedded.81).aspx

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/channel_mgmt.c |   26 ++++++++++++++++++++++++--
 include/linux/hyperv.h    |   21 +++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index bbd812e..759ba4d 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -139,10 +139,32 @@ static const struct vmbus_device vmbus_devs[] = {
 	},
 };
 
-static u16 hv_get_dev_type(const uuid_le *guid)
+static const struct {
+	uuid_le guid;
+} vmbus_unsupported_devs[] = {
+	{ HV_AVMA1_GUID },
+	{ HV_AVMA2_GUID },
+	{ HV_RDV_GUID	},
+};
+
+static bool is_unsupported_vmbus_devs(const uuid_le *guid)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vmbus_unsupported_devs); i++)
+		if (!uuid_le_cmp(*guid, vmbus_unsupported_devs[i].guid))
+			return true;
+	return false;
+}
+
+static u16 hv_get_dev_type(const struct vmbus_channel *channel)
 {
+	const uuid_le *guid = &channel->offermsg.offer.if_type;
 	u16 i;
 
+	if (is_hvsock_channel(channel) || is_unsupported_vmbus_devs(guid))
+		return HV_UNKOWN;
+
 	for (i = HV_IDE; i < HV_UNKOWN; i++) {
 		if (!uuid_le_cmp(*guid, vmbus_devs[i].guid))
 			return i;
@@ -426,7 +448,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 			goto err_free_chan;
 	}
 
-	dev_type = hv_get_dev_type(&newchannel->offermsg.offer.if_type);
+	dev_type = hv_get_dev_type(newchannel);
 	if (dev_type == HV_NIC)
 		set_channel_signal_state(newchannel, HV_SIGNAL_POLICY_EXPLICIT);
 
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 613074e..430619a 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1315,6 +1315,27 @@ u64 hv_do_hypercall(u64 control, void *input, void *output);
 			0x80, 0x2e, 0x27, 0xed, 0xe1, 0x9f)
 
 /*
+ * Linux doesn't support the 3 devices: the first two are for
+ * Automatic Virtual Machine Activation, and the third is for
+ * Remote Desktop Virtualization.
+ * {f8e65716-3cb3-4a06-9a60-1889c5cccab5}
+ * {3375baf4-9e15-4b30-b765-67acb10d607b}
+ * {276aacf4-ac15-426c-98dd-7521ad3f01fe}
+ */
+
+#define HV_AVMA1_GUID \
+	.guid = UUID_LE(0xf8e65716, 0x3cb3, 0x4a06, 0x9a, 0x60, \
+			0x18, 0x89, 0xc5, 0xcc, 0xca, 0xb5)
+
+#define HV_AVMA2_GUID \
+	.guid = UUID_LE(0x3375baf4, 0x9e15, 0x4b30, 0xb7, 0x65, \
+			0x67, 0xac, 0xb1, 0x0d, 0x60, 0x7b)
+
+#define HV_RDV_GUID \
+	.guid = UUID_LE(0x276aacf4, 0xac15, 0x426c, 0x98, 0xdd, \
+			0x75, 0x21, 0xad, 0x3f, 0x01, 0xfe)
+
+/*
  * Common header for Hyper-V ICs
  */
 
-- 
1.7.4.1