Commit 5e4304ff authored by Hamza Mahfooz's avatar Hamza Mahfooz Committed by Wei Liu
Browse files

drivers/hv: introduce vmbus_channel_set_cpu() 



The core functionality in target_cpu_store() is also needed in a
subsequent patch for automatically changing the CPU when taking
a CPU offline. As such, factor out the body of target_cpu_store()
into new function vmbus_channel_set_cpu() that can also be used
elsewhere.

No functional change is intended.

Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: default avatarHamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Reviewed-by: default avatarMichael Kelley <mhklinux@outlook.com>
Tested-by: default avatarMichael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250117203309.192072-2-hamzamahfooz@linux.microsoft.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Message-ID: <20250117203309.192072-2-hamzamahfooz@linux.microsoft.com>
parent 7c0db8a4

drivers/hv/vmbus_drv.c

+31 −21
Original line number Diff line number Diff line
@@ -1611,16 +1611,16 @@ static ssize_t target_cpu_show(struct vmbus_channel *channel, char *buf) 
{

	return sprintf(buf, "%u\n", channel->target_cpu);

}

static ssize_t target_cpu_store(struct vmbus_channel *channel,

				const char *buf, size_t count)



int vmbus_channel_set_cpu(struct vmbus_channel *channel, u32 target_cpu)

{

	u32 target_cpu, origin_cpu;

	ssize_t ret = count;

	u32 origin_cpu;

	int ret = 0;



	if (vmbus_proto_version < VERSION_WIN10_V4_1)

		return -EIO;

	lockdep_assert_cpus_held();

	lockdep_assert_held(&vmbus_connection.channel_mutex);



	if (sscanf(buf, "%uu", &target_cpu) != 1)

	if (vmbus_proto_version < VERSION_WIN10_V4_1)

		return -EIO;



	/* Validate target_cpu for the cpumask_test_cpu() operation below. */
@@ -1630,22 +1630,17 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel, 
	if (!cpumask_test_cpu(target_cpu, housekeeping_cpumask(HK_TYPE_MANAGED_IRQ)))

		return -EINVAL;



	/* No CPUs should come up or down during this. */

	cpus_read_lock();



	if (!cpu_online(target_cpu)) {

		cpus_read_unlock();

	if (!cpu_online(target_cpu))

		return -EINVAL;

	}



	/*

	 * Synchronizes target_cpu_store() and channel closure:

	 * Synchronizes vmbus_channel_set_cpu() and channel closure:

	 *

	 * { Initially: state = CHANNEL_OPENED }

	 *

	 * CPU1				CPU2

	 *

	 * [target_cpu_store()]		[vmbus_disconnect_ring()]

	 * [vmbus_channel_set_cpu()]	[vmbus_disconnect_ring()]

	 *

	 * LOCK channel_mutex		LOCK channel_mutex

	 * LOAD r1 = state		LOAD r2 = state
@@ -1660,7 +1655,6 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel, 
	 * Note.  The host processes the channel messages "sequentially", in

	 * the order in which they are received on a per-partition basis.

	 */

	mutex_lock(&vmbus_connection.channel_mutex);



	/*

	 * Hyper-V will ignore MODIFYCHANNEL messages for "non-open" channels;
@@ -1668,17 +1662,17 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel, 
	 */

	if (channel->state != CHANNEL_OPENED_STATE) {

		ret = -EIO;

		goto cpu_store_unlock;

		goto end;

	}



	origin_cpu = channel->target_cpu;

	if (target_cpu == origin_cpu)

		goto cpu_store_unlock;

		goto end;



	if (vmbus_send_modifychannel(channel,

				     hv_cpu_number_to_vp_number(target_cpu))) {

		ret = -EIO;

		goto cpu_store_unlock;

		goto end;

	}



	/*
@@ -1708,10 +1702,26 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel, 
				origin_cpu, target_cpu);

	}



cpu_store_unlock:

end:

	return ret;

}



static ssize_t target_cpu_store(struct vmbus_channel *channel,

				const char *buf, size_t count)

{

	u32 target_cpu;

	ssize_t ret;



	if (sscanf(buf, "%uu", &target_cpu) != 1)

		return -EIO;



	cpus_read_lock();

	mutex_lock(&vmbus_connection.channel_mutex);

	ret = vmbus_channel_set_cpu(channel, target_cpu);

	mutex_unlock(&vmbus_connection.channel_mutex);

	cpus_read_unlock();

	return ret;



	return ret ?: count;

}

static VMBUS_CHAN_ATTR(cpu, 0644, target_cpu_show, target_cpu_store);

include/linux/hyperv.h

+1 −0
Original line number Diff line number Diff line
@@ -1661,6 +1661,7 @@ int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id, 
				  const guid_t *shv_host_servie_id);

int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp);

void vmbus_set_event(struct vmbus_channel *channel);

int vmbus_channel_set_cpu(struct vmbus_channel *channel, u32 target_cpu);



/* Get the start of the ring buffer. */

static inline void *