Drivers: hv: vmbus: Add module parameter to cap the VMBus version (931cccc9) · Commits · 戴 / test

Currently, Linux guests negotiate the VMBus version with Hyper-V and use the highest available VMBus version they can connect to. This has some drawbacks: by using the highest available version, certain code paths are never executed and can not be tested when the guest runs on the newest host. Add the module parameter "max_version", to upper-bound the VMBus versions guests can negotiate. Suggested-by:

Dexuan Cui <decui@microsoft.com> Signed-off-by:

Andrea Parri <parri.andrea@gmail.com> Reviewed-by:

Wei Liu <wei.liu@kernel.org> Reviewed-by:

Michael Kelley <mikelley@microsoft.com> Signed-off-by:

Sasha Levin <sashal@kernel.org>

drivers/hv/connection.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,7 @@
		#include <linux/wait.h>
		#include <linux/delay.h>
		#include <linux/mm.h>
		#include <linux/module.h>
		#include <linux/slab.h>
		#include <linux/vmalloc.h>
		#include <linux/hyperv.h>
		@@ -55,6 +56,16 @@ static __u32 vmbus_versions[] = {
		VERSION_WS2008
		};

		/*
		* Maximal VMBus protocol version guests can negotiate. Useful to cap the
		* VMBus version for testing and debugging purpose.
		*/
		static uint max_version = VERSION_WIN10_V5_2;

		module_param(max_version, uint, S_IRUGO);
		MODULE_PARM_DESC(max_version,
		"Maximal VMBus protocol version which can be negotiated");

		int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
		{
		int ret = 0;
		@@ -240,6 +251,8 @@ int vmbus_connect(void)
		goto cleanup;

		version = vmbus_versions[i];
		if (version > max_version)
		continue;

		ret = vmbus_negotiate_version(msginfo, version);
		if (ret == -ETIMEDOUT)

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