[PATCH v3 0/3] Drivers: hv: vmbus: Miscellaneous improvements

[PATCH v3 0/3] Drivers: hv: vmbus: Miscellaneous improvements

[Andrea Parri]

Hi all,

The patchset:

  - refactors the VMBus negotiation code by introducing the table of
    VMBus protocol versions (patch 1/3),

  - enables VMBus protocol version 4.1, 5.1 and 5.2 (patch 2/3),

  - introduces a module parameter to cap the VMBus protocol versions
    which a guest can negotiate with the hypervisor (patch 3/3).

Thanks,
  Andrea

---
Changes since v2 ([1]):
  - refactor the loop exit path in vmbus_connect() (Michael Kelley)
  - do not rename VERSION_WIN10 (Michael Kelley)

Changes since v1 ([2]):
  - remove the VERSION_INVAL macro (Vitaly Kuznetsov and Dexuan Cui)
  - make the table of VMBus protocol versions static (Dexuan Cui)
  - enable VMBus protocol version 4.1 (Michael Kelley)
  - introduce module parameter to cap the VMBus version (Dexuan Cui)

[1] https://lkml.kernel.org/r/20191010154600.23875-1-parri.andrea@gmail.com
[2] https://lkml.kernel.org/r/20191007163115.26197-1-parri.andrea@gmail.com

Andrea Parri (3):
  Drivers: hv: vmbus: Introduce table of VMBus protocol versions
  Drivers: hv: vmbus: Enable VMBus protocol versions 4.1, 5.1 and 5.2
  Drivers: hv: vmbus: Add module parameter to cap the VMBus version

 drivers/hv/connection.c | 72 +++++++++++++++++++++--------------------
 drivers/hv/vmbus_drv.c  |  3 +-
 include/linux/hyperv.h  | 12 ++++---
 3 files changed, 45 insertions(+), 42 deletions(-)

-- 
2.23.0

[PATCH v3 1/3] Drivers: hv: vmbus: Introduce table of VMBus protocol versions

[Andrea Parri]

The technique used to get the next VMBus version seems increasisly
clumsy as the number of VMBus versions increases.  Performance is
not a concern since this is only done once during system boot; it's
just that we'll end up with more lines of code than is really needed.

As an alternative, introduce a table with the version numbers listed
in order (from the most recent to the oldest).  vmbus_connect() loops
through the versions listed in the table until it gets an accepted
connection or gets to the end of the table (invalid version).

Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
---
 drivers/hv/connection.c | 50 +++++++++++++++--------------------------
 drivers/hv/vmbus_drv.c  |  3 +--
 include/linux/hyperv.h  |  4 ----
 3 files changed, 19 insertions(+), 38 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 6e4c015783ffc..8dc48f53c1ac4 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -40,29 +40,17 @@ EXPORT_SYMBOL_GPL(vmbus_connection);
 __u32 vmbus_proto_version;
 EXPORT_SYMBOL_GPL(vmbus_proto_version);
 
-static __u32 vmbus_get_next_version(__u32 current_version)
-{
-	switch (current_version) {
-	case (VERSION_WIN7):
-		return VERSION_WS2008;
-
-	case (VERSION_WIN8):
-		return VERSION_WIN7;
-
-	case (VERSION_WIN8_1):
-		return VERSION_WIN8;
-
-	case (VERSION_WIN10):
-		return VERSION_WIN8_1;
-
-	case (VERSION_WIN10_V5):
-		return VERSION_WIN10;
-
-	case (VERSION_WS2008):
-	default:
-		return VERSION_INVAL;
-	}
-}
+/*
+ * Table of VMBus versions listed from newest to oldest.
+ */
+static __u32 vmbus_versions[] = {
+	VERSION_WIN10_V5,
+	VERSION_WIN10,
+	VERSION_WIN8_1,
+	VERSION_WIN8,
+	VERSION_WIN7,
+	VERSION_WS2008
+};
 
 int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 {
@@ -169,8 +157,8 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
  */
 int vmbus_connect(void)
 {
-	int ret = 0;
 	struct vmbus_channel_msginfo *msginfo = NULL;
+	int i, ret = 0;
 	__u32 version;
 
 	/* Initialize the vmbus connection */
@@ -244,21 +232,19 @@ int vmbus_connect(void)
 	 * version.
 	 */
 
-	version = VERSION_CURRENT;
+	for (i = 0; ; i++) {
+		if (i == ARRAY_SIZE(vmbus_versions))
+			goto cleanup;
+
+		version = vmbus_versions[i];
 
-	do {
 		ret = vmbus_negotiate_version(msginfo, version);
 		if (ret == -ETIMEDOUT)
 			goto cleanup;
 
 		if (vmbus_connection.conn_state == CONNECTED)
 			break;
-
-		version = vmbus_get_next_version(version);
-	} while (version != VERSION_INVAL);
-
-	if (version == VERSION_INVAL)
-		goto cleanup;
+	}
 
 	vmbus_proto_version = version;
 	pr_info("Vmbus version:%d.%d\n",
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 53a60c81e220d..0ac874faf7209 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2220,8 +2220,7 @@ static int vmbus_bus_resume(struct device *dev)
 	 * We only use the 'vmbus_proto_version', which was in use before
 	 * hibernation, to re-negotiate with the host.
 	 */
-	if (vmbus_proto_version == VERSION_INVAL ||
-	    vmbus_proto_version == 0) {
+	if (!vmbus_proto_version) {
 		pr_err("Invalid proto version = 0x%x\n", vmbus_proto_version);
 		return -EINVAL;
 	}
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index b4a017093b697..c08b62dbd151f 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -192,10 +192,6 @@ static inline u32 hv_get_avail_to_write_percent(
 #define VERSION_WIN10	((4 << 16) | (0))
 #define VERSION_WIN10_V5 ((5 << 16) | (0))
 
-#define VERSION_INVAL -1
-
-#define VERSION_CURRENT VERSION_WIN10_V5
-
 /* Make maximum size of pipe payload of 16K */
 #define MAX_PIPE_DATA_PAYLOAD		(sizeof(u8) * 16384)
 
-- 
2.23.0

[PATCH v3 2/3] Drivers: hv: vmbus: Enable VMBus protocol versions 4.1, 5.1 and 5.2

[Andrea Parri]

Hyper-V has added VMBus protocol versions 5.1 and 5.2 in recent release
versions.  Allow Linux guests to negotiate these new protocol versions
on versions of Hyper-V that support them.  While on this, also allow
guests to negotiate the VMBus protocol version 4.1 (which was missing).

Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
---
 drivers/hv/connection.c | 13 ++++++++-----
 include/linux/hyperv.h  |  8 +++++++-
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 8dc48f53c1ac4..cadfb34b38d80 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -44,7 +44,10 @@ EXPORT_SYMBOL_GPL(vmbus_proto_version);
  * Table of VMBus versions listed from newest to oldest.
  */
 static __u32 vmbus_versions[] = {
+	VERSION_WIN10_V5_2,
+	VERSION_WIN10_V5_1,
 	VERSION_WIN10_V5,
+	VERSION_WIN10_V4_1,
 	VERSION_WIN10,
 	VERSION_WIN8_1,
 	VERSION_WIN8,
@@ -68,12 +71,12 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 	msg->vmbus_version_requested = version;
 
 	/*
-	 * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
-	 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
+	 * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
+	 * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
 	 * and for subsequent messages, we must use the Message Connection ID
 	 * field in the host-returned Version Response Message. And, with
-	 * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
-	 * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
+	 * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
+	 * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
 	 * compatibility.
 	 *
 	 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
@@ -399,7 +402,7 @@ int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 		case HV_STATUS_INVALID_CONNECTION_ID:
 			/*
 			 * See vmbus_negotiate_version(): VMBus protocol 5.0
-			 * requires that we must use
+			 * and higher require that we must use
 			 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
 			 * Contact message, but on old hosts that only
 			 * support VMBus protocol 4.0 or lower, here we get
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c08b62dbd151f..f17f2cd22e39f 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -182,15 +182,21 @@ static inline u32 hv_get_avail_to_write_percent(
  * 2 . 4  (Windows 8)
  * 3 . 0  (Windows 8 R2)
  * 4 . 0  (Windows 10)
+ * 4 . 1  (Windows 10 RS3)
  * 5 . 0  (Newer Windows 10)
+ * 5 . 1  (Windows 10 RS4)
+ * 5 . 2  (Windows Server 2019, RS5)
  */
 
 #define VERSION_WS2008  ((0 << 16) | (13))
 #define VERSION_WIN7    ((1 << 16) | (1))
 #define VERSION_WIN8    ((2 << 16) | (4))
 #define VERSION_WIN8_1    ((3 << 16) | (0))
-#define VERSION_WIN10	((4 << 16) | (0))
+#define VERSION_WIN10 ((4 << 16) | (0))
+#define VERSION_WIN10_V4_1 ((4 << 16) | (1))
 #define VERSION_WIN10_V5 ((5 << 16) | (0))
+#define VERSION_WIN10_V5_1 ((5 << 16) | (1))
+#define VERSION_WIN10_V5_2 ((5 << 16) | (2))
 
 /* Make maximum size of pipe payload of 16K */
 #define MAX_PIPE_DATA_PAYLOAD		(sizeof(u8) * 16384)
-- 
2.23.0

[PATCH v3 3/3] Drivers: hv: vmbus: Add module parameter to cap the VMBus version

[Andrea Parri]

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>
---
 drivers/hv/connection.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index cadfb34b38d80..0475be4356dd7 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -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)
-- 
2.23.0

RE: [PATCH v3 1/3] Drivers: hv: vmbus: Introduce table of VMBus protocol versions

[Michael Kelley]

From: Andrea Parri <parri.andrea@gmail.com> Sent: Tuesday, October 15, 2019 4:47 AM
> 
> The technique used to get the next VMBus version seems increasisly
> clumsy as the number of VMBus versions increases.  Performance is
> not a concern since this is only done once during system boot; it's
> just that we'll end up with more lines of code than is really needed.
> 
> As an alternative, introduce a table with the version numbers listed
> in order (from the most recent to the oldest).  vmbus_connect() loops
> through the versions listed in the table until it gets an accepted
> connection or gets to the end of the table (invalid version).
> 
> Suggested-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
> ---
>  drivers/hv/connection.c | 50 +++++++++++++++--------------------------
>  drivers/hv/vmbus_drv.c  |  3 +--
>  include/linux/hyperv.h  |  4 ----
>  3 files changed, 19 insertions(+), 38 deletions(-)
> 

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

RE: [PATCH v3 2/3] Drivers: hv: vmbus: Enable VMBus protocol versions 4.1, 5.1 and 5.2

[Michael Kelley]

From: Andrea Parri <parri.andrea@gmail.com> Sent: Tuesday, October 15, 2019 4:47 AM
> 
> Hyper-V has added VMBus protocol versions 5.1 and 5.2 in recent release
> versions.  Allow Linux guests to negotiate these new protocol versions
> on versions of Hyper-V that support them.  While on this, also allow
> guests to negotiate the VMBus protocol version 4.1 (which was missing).
> 
> Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
> ---
>  drivers/hv/connection.c | 13 ++++++++-----
>  include/linux/hyperv.h  |  8 +++++++-
>  2 files changed, 15 insertions(+), 6 deletions(-)
> 

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

RE: [PATCH v3 3/3] Drivers: hv: vmbus: Add module parameter to cap the VMBus version

[Michael Kelley]

From: Andrea Parri <parri.andrea@gmail.com> Sent: Tuesday, October 15, 2019 4:47 AM
> 
> 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>
> ---
>  drivers/hv/connection.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 

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

Re: [PATCH v3 0/3] Drivers: hv: vmbus: Miscellaneous improvements

[Wei Liu]

On Tue, 15 Oct 2019 at 12:47, Andrea Parri <parri.andrea@gmail.com> wrote:
[...]
> [1] https://lkml.kernel.org/r/20191010154600.23875-1-parri.andrea@gmail.com
> [2] https://lkml.kernel.org/r/20191007163115.26197-1-parri.andrea@gmail.com
>
> Andrea Parri (3):
>   Drivers: hv: vmbus: Introduce table of VMBus protocol versions
>   Drivers: hv: vmbus: Enable VMBus protocol versions 4.1, 5.1 and 5.2
>   Drivers: hv: vmbus: Add module parameter to cap the VMBus version

For the whole series:

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

Re: [PATCH v3 0/3] Drivers: hv: vmbus: Miscellaneous improvements

[Sasha Levin]

On Tue, Oct 15, 2019 at 01:46:43PM +0200, Andrea Parri wrote:
>Hi all,
>
>The patchset:
>
>  - refactors the VMBus negotiation code by introducing the table of
>    VMBus protocol versions (patch 1/3),
>
>  - enables VMBus protocol version 4.1, 5.1 and 5.2 (patch 2/3),
>
>  - introduces a module parameter to cap the VMBus protocol versions
>    which a guest can negotiate with the hypervisor (patch 3/3).

Queued up for hyperv-next, thanks!

-- 
Thanks,
Sasha