Drivers: hv: vmbus: Remove the target_vp field from the vmbus_channel struct

The field is read only in __vmbus_open() and it is already stored twice
(after a call to hv_cpu_number_to_vp_number()) in target_cpu_store() and
init_vp_index(); there is no need to "cache" its value in the channel
data structure.

Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-2-parri.andrea@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

drivers/hv/channel.c

@@ -18,6 +18,7 @@
 #include <linux/uio.h>
 #include <linux/interrupt.h>
 #include <asm/page.h>
+#include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
 
@@ -176,7 +177,7 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
 	open_msg->child_relid = newchannel->offermsg.child_relid;
 	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
 	open_msg->downstream_ringbuffer_pageoffset = newchannel->ringbuffer_send_offset;
-	open_msg->target_vp = newchannel->target_vp;
+	open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
 
 	if (userdatalen)
 		memcpy(open_msg->userdata, userdata, userdatalen);

drivers/hv/channel_mgmt.c

@@ -704,8 +704,6 @@ static void init_vp_index(struct vmbus_channel *channel)
 		 */
 		channel->numa_node = cpu_to_node(VMBUS_CONNECT_CPU);
 		channel->target_cpu = VMBUS_CONNECT_CPU;
-		channel->target_vp =
-			hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 		if (perf_chn)
 			hv_set_alloced_cpu(VMBUS_CONNECT_CPU);
 		return;
@@ -739,7 +737,6 @@ static void init_vp_index(struct vmbus_channel *channel)
 	cpumask_set_cpu(target_cpu, alloced_mask);
 
 	channel->target_cpu = target_cpu;
-	channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);
 
 	free_cpumask_var(available_mask);
 }

drivers/hv/vmbus_drv.c

@@ -23,7 +23,6 @@
 #include <linux/cpu.h>
 #include <linux/sched/task_stack.h>
 
-#include <asm/mshyperv.h>
 #include <linux/delay.h>
 #include <linux/notifier.h>
 #include <linux/ptrace.h>
@@ -1779,7 +1778,6 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel,
 	 */
 
 	channel->target_cpu = target_cpu;
-	channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);
 	channel->numa_node = cpu_to_node(target_cpu);
 
 	/* See init_vp_index(). */

include/linux/hyperv.h

@@ -803,15 +803,14 @@ struct vmbus_channel {
 	u64 sig_event;
 
 	/*
-	 * Starting with win8, this field will be used to specify
-	 * the target virtual processor on which to deliver the interrupt for
-	 * the host to guest communication.
-	 * Prior to win8, incoming channel interrupts would only
-	 * be delivered on cpu 0. Setting this value to 0 would
-	 * preserve the earlier behavior.
+	 * Starting with win8, this field will be used to specify the
+	 * target CPU on which to deliver the interrupt for the host
+	 * to guest communication.
+	 *
+	 * Prior to win8, incoming channel interrupts would only be
+	 * delivered on CPU 0. Setting this value to 0 would preserve
+	 * the earlier behavior.
 	 */
-	u32 target_vp;
-	/* The corresponding CPUID in the guest */
 	u32 target_cpu;
 	int numa_node;
 	/*