diff mbox

[02/15] hyperv: uapi-fy synic event flags definitions

Message ID 20161220155602.6298-3-rkagan@virtuozzo.com (mailing list archive)
State New, archived
Headers show

Commit Message

Roman Kagan Dec. 20, 2016, 3:55 p.m. UTC
Move definitions related to the Hyper-V SynIC event flags to a header
where they can be consumed by userspace.

While doing so, also clean up their use by switching to standard bitops
and struct-based dereferencing.  The latter is also done for message
pages.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/include/uapi/asm/hyperv.h | 13 +++++++++
 drivers/hv/hyperv_vmbus.h          | 24 ++--------------
 drivers/hv/channel_mgmt.c          | 10 +++----
 drivers/hv/connection.c            | 47 ++++++++++---------------------
 drivers/hv/vmbus_drv.c             | 57 ++++++++++++++------------------------
 5 files changed, 54 insertions(+), 97 deletions(-)

Comments

Roman Kagan Dec. 21, 2016, 6:33 a.m. UTC | #1
On Tue, Dec 20, 2016 at 09:24:53AM -0800, Stephen Hemminger wrote:
> On Tue, 20 Dec 2016 18:55:49 +0300
> Roman Kagan <rkagan@virtuozzo.com> wrote:
> 
> > Move definitions related to the Hyper-V SynIC event flags to a header
> > where they can be consumed by userspace.
> > 
> > While doing so, also clean up their use by switching to standard bitops
> > and struct-based dereferencing.  The latter is also done for message
> > pages.
> > 
> > Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> > ---
> >  arch/x86/include/uapi/asm/hyperv.h | 13 +++++++++
> >  drivers/hv/hyperv_vmbus.h          | 24 ++--------------
> >  drivers/hv/channel_mgmt.c          | 10 +++----
> >  drivers/hv/connection.c            | 47 ++++++++++---------------------
> >  drivers/hv/vmbus_drv.c             | 57 ++++++++++++++------------------------
> >  5 files changed, 54 insertions(+), 97 deletions(-)
> > 
> > diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
> > index 6098ab5..af542a3 100644
> > --- a/arch/x86/include/uapi/asm/hyperv.h
> > +++ b/arch/x86/include/uapi/asm/hyperv.h
> > @@ -363,4 +363,17 @@ struct hv_timer_message_payload {
> >  #define HV_STIMER_AUTOENABLE		(1ULL << 3)
> >  #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) & 0x0F)
> >  
> > +/* Define synthetic interrupt controller flag constants. */
> > +#define HV_EVENT_FLAGS_COUNT		(256 * 8)
> > +
> > +/* Define the synthetic interrupt controller event flags format. */
> > +struct hv_synic_event_flags {
> > +	__u64 flags[HV_EVENT_FLAGS_COUNT / 64];
> > +};
> > +
> > +/* Define the synthetic interrupt flags page layout. */
> > +struct hv_synic_event_flags_page {
> > +	struct hv_synic_event_flags sintevent_flags[HV_SYNIC_SINT_COUNT];
> > +};
> > +
> >  #endif
> 
> How are these going to be exposed to user space?
> 
> They should really be unsigned long since there is no guarantee of atomic operation
> on 64 bit values on 32 bit architectures.

Indeed, absolutely.  These are bitmaps and should be unsigned long[], of
course.  I'll fix it in the next iteration.

Thanks,
Roman.
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kernel test robot Dec. 21, 2016, 10:58 a.m. UTC | #2
Hi Roman,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.9 next-20161221]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Roman-Kagan/hyperv-more-stuff-to-uapi-cleanup/20161221-130415
config: x86_64-rhel (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: the linux-review/Roman-Kagan/hyperv-more-stuff-to-uapi-cleanup/20161221-130415 HEAD 35a54cd6795c4aa6f101c58ab076c6bdd63b3779 builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   drivers/hv/connection.c: In function 'vmbus_set_event':
>> drivers/hv/connection.c:473:3: error: implicit declaration of function 'sync_set_bit' [-Werror=implicit-function-declaration]
      sync_set_bit(child_relid & 31,
      ^~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   drivers/hv/channel.c: In function 'vmbus_setevent':
>> drivers/hv/channel.c:53:3: error: implicit declaration of function 'sync_set_bit' [-Werror=implicit-function-declaration]
      sync_set_bit(channel->offermsg.child_relid & 31,
      ^~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/sync_set_bit +473 drivers/hv/connection.c

1b807e101 drivers/hv/connection.c         K. Y. Srinivasan 2015-12-21  467  void vmbus_set_event(struct vmbus_channel *channel)
3e7ee4902 drivers/staging/hv/Connection.c Hank Janssen     2009-07-13  468  {
21c3bef5d drivers/hv/connection.c         K. Y. Srinivasan 2012-12-01  469  	u32 child_relid = channel->offermsg.child_relid;
3be777740 drivers/hv/connection.c         K. Y. Srinivasan 2012-12-01  470  
3be777740 drivers/hv/connection.c         K. Y. Srinivasan 2012-12-01  471  	if (!channel->is_dedicated_interrupt) {
454f18a96 drivers/staging/hv/Connection.c Bill Pemberton   2009-07-27  472  		/* Each u32 represents 32 channels */
223565857 drivers/staging/hv/connection.c Olaf Hering      2011-03-21 @473  		sync_set_bit(child_relid & 31,
da9fcb726 drivers/staging/hv/connection.c Haiyang Zhang    2011-01-26  474  			(unsigned long *)vmbus_connection.send_int_page +
15b2f6479 drivers/staging/hv/connection.c Haiyang Zhang    2011-01-26  475  			(child_relid >> 5));
3be777740 drivers/hv/connection.c         K. Y. Srinivasan 2012-12-01  476  	}

:::::: The code at line 473 was first introduced by commit
:::::: 22356585712d1ff08fbfed152edd8b386873b238 staging: hv: use sync_bitops when interacting with the hypervisor

:::::: TO: Olaf Hering <olaf@aepfle.de>
:::::: CC: Greg Kroah-Hartman <gregkh@suse.de>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
KY Srinivasan Dec. 21, 2016, 6:58 p.m. UTC | #3
> -----Original Message-----
> From: Roman Kagan [mailto:rkagan@virtuozzo.com]
> Sent: Tuesday, December 20, 2016 7:56 AM
> To: Paolo Bonzini <pbonzini@redhat.com>; Radim Krčmář
> <rkrcmar@redhat.com>; KY Srinivasan <kys@microsoft.com>; Vitaly
> Kuznetsov <vkuznets@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar
> <mingo@redhat.com>; H. Peter Anvin <hpa@zytor.com>; x86@kernel.org;
> Haiyang Zhang <haiyangz@microsoft.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; devel@linuxdriverproject.org; Denis V . Lunev
> <den@openvz.org>; Roman Kagan <rkagan@virtuozzo.com>
> Subject: [PATCH 02/15] hyperv: uapi-fy synic event flags definitions
> 
> Move definitions related to the Hyper-V SynIC event flags to a header
> where they can be consumed by userspace.
> 
> While doing so, also clean up their use by switching to standard bitops
> and struct-based dereferencing.  The latter is also done for message
> pages.

Please breakup this patch.
> 
> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> ---
>  arch/x86/include/uapi/asm/hyperv.h | 13 +++++++++
>  drivers/hv/hyperv_vmbus.h          | 24 ++--------------
>  drivers/hv/channel_mgmt.c          | 10 +++----
>  drivers/hv/connection.c            | 47 ++++++++++---------------------
>  drivers/hv/vmbus_drv.c             | 57 ++++++++++++++------------------------
>  5 files changed, 54 insertions(+), 97 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/hyperv.h
> b/arch/x86/include/uapi/asm/hyperv.h
> index 6098ab5..af542a3 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -363,4 +363,17 @@ struct hv_timer_message_payload {
>  #define HV_STIMER_AUTOENABLE		(1ULL << 3)
>  #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) &
> 0x0F)
> 
> +/* Define synthetic interrupt controller flag constants. */
> +#define HV_EVENT_FLAGS_COUNT		(256 * 8)
> +
> +/* Define the synthetic interrupt controller event flags format. */
> +struct hv_synic_event_flags {
> +	__u64 flags[HV_EVENT_FLAGS_COUNT / 64];
> +};
> +
> +/* Define the synthetic interrupt flags page layout. */
> +struct hv_synic_event_flags_page {
> +	struct hv_synic_event_flags
> sintevent_flags[HV_SYNIC_SINT_COUNT];
> +};
> +
>  #endif
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 4516498..4fab154 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -26,7 +26,6 @@
>  #define _HYPERV_VMBUS_H
> 
>  #include <linux/list.h>
> -#include <asm/sync_bitops.h>
>  #include <linux/atomic.h>
>  #include <linux/hyperv.h>
> 
> @@ -75,11 +74,6 @@ enum hv_cpuid_function {
> 
>  #define HV_ANY_VP			(0xFFFFFFFF)
> 
> -/* Define synthetic interrupt controller flag constants. */
> -#define HV_EVENT_FLAGS_COUNT		(256 * 8)
> -#define HV_EVENT_FLAGS_BYTE_COUNT	(256)
> -#define HV_EVENT_FLAGS_DWORD_COUNT	(256 / sizeof(u32))
> -
>  /* Define invalid partition identifier. */
>  #define HV_PARTITION_ID_INVALID		((u64)0x0)
> 
> @@ -146,20 +140,6 @@ union hv_timer_config {
>  	};
>  };
> 
> -/* Define the number of message buffers associated with each port. */
> -#define HV_PORT_MESSAGE_BUFFER_COUNT	(16)
> -
> -/* Define the synthetic interrupt controller event flags format. */
> -union hv_synic_event_flags {
> -	u8 flags8[HV_EVENT_FLAGS_BYTE_COUNT];
> -	u32 flags32[HV_EVENT_FLAGS_DWORD_COUNT];
> -};
> -
> -/* Define the synthetic interrupt flags page layout. */
> -struct hv_synic_event_flags_page {
> -	union hv_synic_event_flags
> sintevent_flags[HV_SYNIC_SINT_COUNT];
> -};
> -
>  /* Define SynIC control register. */
>  union hv_synic_scontrol {
>  	u64 as_uint64;
> @@ -434,8 +414,8 @@ struct hv_context {
> 
>  	bool synic_initialized;
> 
> -	void *synic_message_page[NR_CPUS];
> -	void *synic_event_page[NR_CPUS];
> +	struct hv_message_page *synic_message_page[NR_CPUS];
> +	struct hv_synic_event_flags_page *synic_event_page[NR_CPUS];
>  	/*
>  	 * Hypervisor's notion of virtual processor ID is different from
>  	 * Linux' notion of CPU ID. This information can only be retrieved
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 26b4192..49eaae2 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -654,7 +654,6 @@ static void init_vp_index(struct vmbus_channel
> *channel, u16 dev_type)
>  static void vmbus_wait_for_unload(void)
>  {
>  	int cpu;
> -	void *page_addr;
>  	struct hv_message *msg;
>  	struct vmbus_channel_message_header *hdr;
>  	u32 message_type;
> @@ -673,9 +672,8 @@ static void vmbus_wait_for_unload(void)
>  			break;
> 
>  		for_each_online_cpu(cpu) {
> -			page_addr = hv_context.synic_message_page[cpu];
> -			msg = (struct hv_message *)page_addr +
> -				VMBUS_MESSAGE_SINT;
> +			msg = &hv_context.synic_message_page[cpu]->
> +
> 	sint_message[VMBUS_MESSAGE_SINT];
> 
>  			message_type = READ_ONCE(msg-
> >header.message_type);
>  			if (message_type == HVMSG_NONE)
> @@ -699,8 +697,8 @@ static void vmbus_wait_for_unload(void)
>  	 * messages after we reconnect.
>  	 */
>  	for_each_online_cpu(cpu) {
> -		page_addr = hv_context.synic_message_page[cpu];
> -		msg = (struct hv_message *)page_addr +
> VMBUS_MESSAGE_SINT;
> +		msg = &hv_context.synic_message_page[cpu]->
> +				sint_message[VMBUS_MESSAGE_SINT];
>  		msg->header.message_type = HVMSG_NONE;
>  	}
>  }
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index 6ce8b87..aaa2103 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -381,17 +381,12 @@ static void process_chn_event(u32 relid)
>   */
>  void vmbus_on_event(unsigned long data)
>  {
> -	u32 dword;
> -	u32 maxdword;
> -	int bit;
> -	u32 relid;
> -	u32 *recv_int_page = NULL;
> -	void *page_addr;
> +	u32 relid, max_relid;
> +	unsigned long *recv_int_page;
>  	int cpu = smp_processor_id();
> -	union hv_synic_event_flags *event;
> 
>  	if (vmbus_proto_version < VERSION_WIN8) {
> -		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
> +		max_relid = MAX_NUM_CHANNELS_SUPPORTED;
>  		recv_int_page = vmbus_connection.recv_int_page;
>  	} else {
>  		/*
> @@ -399,36 +394,22 @@ void vmbus_on_event(unsigned long data)
>  		 * can be directly checked to get the id of the channel
>  		 * that has the interrupt pending.
>  		 */
> -		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
> -		page_addr = hv_context.synic_event_page[cpu];
> -		event = (union hv_synic_event_flags *)page_addr +
> -						 VMBUS_MESSAGE_SINT;
> -		recv_int_page = event->flags32;
> +		struct hv_synic_event_flags *event =
> +			&hv_context.synic_event_page[cpu]->
> +				sintevent_flags[VMBUS_MESSAGE_SINT];
> +		max_relid = HV_EVENT_FLAGS_COUNT;
> +		recv_int_page = (unsigned long *)event->flags;
>  	}
> 
> -
> -
>  	/* Check events */
>  	if (!recv_int_page)
>  		return;
> -	for (dword = 0; dword < maxdword; dword++) {
> -		if (!recv_int_page[dword])
> -			continue;
> -		for (bit = 0; bit < 32; bit++) {
> -			if (sync_test_and_clear_bit(bit,
> -				(unsigned long *)&recv_int_page[dword])) {
> -				relid = (dword << 5) + bit;
> -
> -				if (relid == 0)
> -					/*
> -					 * Special case - vmbus
> -					 * channel protocol msg
> -					 */
> -					continue;
> -
> -				process_chn_event(relid);
> -			}
> -		}
> +
> +	/* relid == 0 is vmbus channel protocol msg */
> +	relid = 1;
> +	for_each_set_bit_from(relid, recv_int_page, max_relid) {
> +		clear_bit(relid, recv_int_page);

We are using this test_and_clear_bit paradigm for locking. The current code
used the sync variant to ensure the host saw the changes we were making
here (clearing the bit). You may want to add a barrier here or use the sync
variant.
 
> +		process_chn_event(relid);
>  	}
>  }
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 230c62e..13dd210 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -872,9 +872,8 @@ static void hv_process_timer_expiration(struct
> hv_message *msg, int cpu)
>  void vmbus_on_msg_dpc(unsigned long data)
>  {
>  	int cpu = smp_processor_id();
> -	void *page_addr = hv_context.synic_message_page[cpu];
> -	struct hv_message *msg = (struct hv_message *)page_addr +
> -				  VMBUS_MESSAGE_SINT;
> +	struct hv_message *msg = &hv_context.synic_message_page[cpu]-
> >
> +
> 	sint_message[VMBUS_MESSAGE_SINT];
>  	struct vmbus_channel_message_header *hdr;
>  	struct vmbus_channel_message_table_entry *entry;
>  	struct onmessage_work_context *ctx;
> @@ -911,54 +910,40 @@ void vmbus_on_msg_dpc(unsigned long data)
>  static void vmbus_isr(void)
>  {
>  	int cpu = smp_processor_id();
> -	void *page_addr;
>  	struct hv_message *msg;
> -	union hv_synic_event_flags *event;
> -	bool handled = false;
> +	struct hv_synic_event_flags *event;
> 
> -	page_addr = hv_context.synic_event_page[cpu];
> -	if (page_addr == NULL)
> +	if (!hv_context.synic_event_page[cpu])
>  		return;
> 
> -	event = (union hv_synic_event_flags *)page_addr +
> -					 VMBUS_MESSAGE_SINT;
> +	event = &hv_context.synic_event_page[cpu]->
> +			sintevent_flags[VMBUS_MESSAGE_SINT];
>  	/*
>  	 * Check for events before checking for messages. This is the order
>  	 * in which events and messages are checked in Windows guests on
>  	 * Hyper-V, and the Windows team suggested we do the same.
>  	 */
> 
> -	if ((vmbus_proto_version == VERSION_WS2008) ||
> -		(vmbus_proto_version == VERSION_WIN7)) {
> -
> +	/* On win8 and above the channel interrupts are signaled directly in
> +	 * the event page and will be checked in the .event_dpc
> +	 */
> +	if (vmbus_proto_version >= VERSION_WIN8 ||
>  		/* Since we are a child, we only need to check bit 0 */
> -		if (sync_test_and_clear_bit(0,
> -			(unsigned long *) &event->flags32[0])) {
> -			handled = true;
> -		}
> -	} else {
> -		/*
> -		 * Our host is win8 or above. The signaling mechanism
> -		 * has changed and we can directly look at the event page.
> -		 * If bit n is set then we have an interrup on the channel
> -		 * whose id is n.
> -		 */
> -		handled = true;
> -	}
> -
> -	if (handled)
> +	    test_and_clear_bit(0, (unsigned long *)event->flags))

Don't we need the sync variant of test_and_clear_bit here.

>  		tasklet_schedule(hv_context.event_dpc[cpu]);
> 
> -
> -	page_addr = hv_context.synic_message_page[cpu];
> -	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
> +	msg = &hv_context.synic_message_page[cpu]->
> +			sint_message[VMBUS_MESSAGE_SINT];
> 
>  	/* Check if there are actual msgs to be processed */
> -	if (msg->header.message_type != HVMSG_NONE) {
> -		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
> -			hv_process_timer_expiration(msg, cpu);
> -		else
> -			tasklet_schedule(hv_context.msg_dpc[cpu]);
> +	switch (READ_ONCE(msg->header.message_type)) {
> +	case HVMSG_NONE:
> +		break;
> +	case HVMSG_TIMER_EXPIRED:
> +		hv_process_timer_expiration(msg, cpu);
> +		break;
> +	default:
> +		tasklet_schedule(hv_context.msg_dpc[cpu]);
>  	}
> 
>  	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
> --
> 2.9.3

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diff mbox

Patch

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 6098ab5..af542a3 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -363,4 +363,17 @@  struct hv_timer_message_payload {
 #define HV_STIMER_AUTOENABLE		(1ULL << 3)
 #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) & 0x0F)
 
+/* Define synthetic interrupt controller flag constants. */
+#define HV_EVENT_FLAGS_COUNT		(256 * 8)
+
+/* Define the synthetic interrupt controller event flags format. */
+struct hv_synic_event_flags {
+	__u64 flags[HV_EVENT_FLAGS_COUNT / 64];
+};
+
+/* Define the synthetic interrupt flags page layout. */
+struct hv_synic_event_flags_page {
+	struct hv_synic_event_flags sintevent_flags[HV_SYNIC_SINT_COUNT];
+};
+
 #endif
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 4516498..4fab154 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -26,7 +26,6 @@ 
 #define _HYPERV_VMBUS_H
 
 #include <linux/list.h>
-#include <asm/sync_bitops.h>
 #include <linux/atomic.h>
 #include <linux/hyperv.h>
 
@@ -75,11 +74,6 @@  enum hv_cpuid_function {
 
 #define HV_ANY_VP			(0xFFFFFFFF)
 
-/* Define synthetic interrupt controller flag constants. */
-#define HV_EVENT_FLAGS_COUNT		(256 * 8)
-#define HV_EVENT_FLAGS_BYTE_COUNT	(256)
-#define HV_EVENT_FLAGS_DWORD_COUNT	(256 / sizeof(u32))
-
 /* Define invalid partition identifier. */
 #define HV_PARTITION_ID_INVALID		((u64)0x0)
 
@@ -146,20 +140,6 @@  union hv_timer_config {
 	};
 };
 
-/* Define the number of message buffers associated with each port. */
-#define HV_PORT_MESSAGE_BUFFER_COUNT	(16)
-
-/* Define the synthetic interrupt controller event flags format. */
-union hv_synic_event_flags {
-	u8 flags8[HV_EVENT_FLAGS_BYTE_COUNT];
-	u32 flags32[HV_EVENT_FLAGS_DWORD_COUNT];
-};
-
-/* Define the synthetic interrupt flags page layout. */
-struct hv_synic_event_flags_page {
-	union hv_synic_event_flags sintevent_flags[HV_SYNIC_SINT_COUNT];
-};
-
 /* Define SynIC control register. */
 union hv_synic_scontrol {
 	u64 as_uint64;
@@ -434,8 +414,8 @@  struct hv_context {
 
 	bool synic_initialized;
 
-	void *synic_message_page[NR_CPUS];
-	void *synic_event_page[NR_CPUS];
+	struct hv_message_page *synic_message_page[NR_CPUS];
+	struct hv_synic_event_flags_page *synic_event_page[NR_CPUS];
 	/*
 	 * Hypervisor's notion of virtual processor ID is different from
 	 * Linux' notion of CPU ID. This information can only be retrieved
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 26b4192..49eaae2 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -654,7 +654,6 @@  static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
 static void vmbus_wait_for_unload(void)
 {
 	int cpu;
-	void *page_addr;
 	struct hv_message *msg;
 	struct vmbus_channel_message_header *hdr;
 	u32 message_type;
@@ -673,9 +672,8 @@  static void vmbus_wait_for_unload(void)
 			break;
 
 		for_each_online_cpu(cpu) {
-			page_addr = hv_context.synic_message_page[cpu];
-			msg = (struct hv_message *)page_addr +
-				VMBUS_MESSAGE_SINT;
+			msg = &hv_context.synic_message_page[cpu]->
+					sint_message[VMBUS_MESSAGE_SINT];
 
 			message_type = READ_ONCE(msg->header.message_type);
 			if (message_type == HVMSG_NONE)
@@ -699,8 +697,8 @@  static void vmbus_wait_for_unload(void)
 	 * messages after we reconnect.
 	 */
 	for_each_online_cpu(cpu) {
-		page_addr = hv_context.synic_message_page[cpu];
-		msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+		msg = &hv_context.synic_message_page[cpu]->
+				sint_message[VMBUS_MESSAGE_SINT];
 		msg->header.message_type = HVMSG_NONE;
 	}
 }
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 6ce8b87..aaa2103 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -381,17 +381,12 @@  static void process_chn_event(u32 relid)
  */
 void vmbus_on_event(unsigned long data)
 {
-	u32 dword;
-	u32 maxdword;
-	int bit;
-	u32 relid;
-	u32 *recv_int_page = NULL;
-	void *page_addr;
+	u32 relid, max_relid;
+	unsigned long *recv_int_page;
 	int cpu = smp_processor_id();
-	union hv_synic_event_flags *event;
 
 	if (vmbus_proto_version < VERSION_WIN8) {
-		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
+		max_relid = MAX_NUM_CHANNELS_SUPPORTED;
 		recv_int_page = vmbus_connection.recv_int_page;
 	} else {
 		/*
@@ -399,36 +394,22 @@  void vmbus_on_event(unsigned long data)
 		 * can be directly checked to get the id of the channel
 		 * that has the interrupt pending.
 		 */
-		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
-		page_addr = hv_context.synic_event_page[cpu];
-		event = (union hv_synic_event_flags *)page_addr +
-						 VMBUS_MESSAGE_SINT;
-		recv_int_page = event->flags32;
+		struct hv_synic_event_flags *event =
+			&hv_context.synic_event_page[cpu]->
+				sintevent_flags[VMBUS_MESSAGE_SINT];
+		max_relid = HV_EVENT_FLAGS_COUNT;
+		recv_int_page = (unsigned long *)event->flags;
 	}
 
-
-
 	/* Check events */
 	if (!recv_int_page)
 		return;
-	for (dword = 0; dword < maxdword; dword++) {
-		if (!recv_int_page[dword])
-			continue;
-		for (bit = 0; bit < 32; bit++) {
-			if (sync_test_and_clear_bit(bit,
-				(unsigned long *)&recv_int_page[dword])) {
-				relid = (dword << 5) + bit;
-
-				if (relid == 0)
-					/*
-					 * Special case - vmbus
-					 * channel protocol msg
-					 */
-					continue;
-
-				process_chn_event(relid);
-			}
-		}
+
+	/* relid == 0 is vmbus channel protocol msg */
+	relid = 1;
+	for_each_set_bit_from(relid, recv_int_page, max_relid) {
+		clear_bit(relid, recv_int_page);
+		process_chn_event(relid);
 	}
 }
 
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 230c62e..13dd210 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -872,9 +872,8 @@  static void hv_process_timer_expiration(struct hv_message *msg, int cpu)
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	int cpu = smp_processor_id();
-	void *page_addr = hv_context.synic_message_page[cpu];
-	struct hv_message *msg = (struct hv_message *)page_addr +
-				  VMBUS_MESSAGE_SINT;
+	struct hv_message *msg = &hv_context.synic_message_page[cpu]->
+					sint_message[VMBUS_MESSAGE_SINT];
 	struct vmbus_channel_message_header *hdr;
 	struct vmbus_channel_message_table_entry *entry;
 	struct onmessage_work_context *ctx;
@@ -911,54 +910,40 @@  void vmbus_on_msg_dpc(unsigned long data)
 static void vmbus_isr(void)
 {
 	int cpu = smp_processor_id();
-	void *page_addr;
 	struct hv_message *msg;
-	union hv_synic_event_flags *event;
-	bool handled = false;
+	struct hv_synic_event_flags *event;
 
-	page_addr = hv_context.synic_event_page[cpu];
-	if (page_addr == NULL)
+	if (!hv_context.synic_event_page[cpu])
 		return;
 
-	event = (union hv_synic_event_flags *)page_addr +
-					 VMBUS_MESSAGE_SINT;
+	event = &hv_context.synic_event_page[cpu]->
+			sintevent_flags[VMBUS_MESSAGE_SINT];
 	/*
 	 * Check for events before checking for messages. This is the order
 	 * in which events and messages are checked in Windows guests on
 	 * Hyper-V, and the Windows team suggested we do the same.
 	 */
 
-	if ((vmbus_proto_version == VERSION_WS2008) ||
-		(vmbus_proto_version == VERSION_WIN7)) {
-
+	/* On win8 and above the channel interrupts are signaled directly in
+	 * the event page and will be checked in the .event_dpc
+	 */
+	if (vmbus_proto_version >= VERSION_WIN8 ||
 		/* Since we are a child, we only need to check bit 0 */
-		if (sync_test_and_clear_bit(0,
-			(unsigned long *) &event->flags32[0])) {
-			handled = true;
-		}
-	} else {
-		/*
-		 * Our host is win8 or above. The signaling mechanism
-		 * has changed and we can directly look at the event page.
-		 * If bit n is set then we have an interrup on the channel
-		 * whose id is n.
-		 */
-		handled = true;
-	}
-
-	if (handled)
+	    test_and_clear_bit(0, (unsigned long *)event->flags))
 		tasklet_schedule(hv_context.event_dpc[cpu]);
 
-
-	page_addr = hv_context.synic_message_page[cpu];
-	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+	msg = &hv_context.synic_message_page[cpu]->
+			sint_message[VMBUS_MESSAGE_SINT];
 
 	/* Check if there are actual msgs to be processed */
-	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, cpu);
-		else
-			tasklet_schedule(hv_context.msg_dpc[cpu]);
+	switch (READ_ONCE(msg->header.message_type)) {
+	case HVMSG_NONE:
+		break;
+	case HVMSG_TIMER_EXPIRED:
+		hv_process_timer_expiration(msg, cpu);
+		break;
+	default:
+		tasklet_schedule(hv_context.msg_dpc[cpu]);
 	}
 
 	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);