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drivers/hv: introduce vmbus_channel_set_cpu()

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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: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250117203309.192072-2-hamzamahfooz@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250117203309.192072-2-hamzamahfooz@linux.microsoft.com>
This commit is contained in:
Hamza Mahfooz
2025-01-17 15:33:07 -05:00
committed by Wei Liu
parent 7c0db8a4f5
commit 5e4304ff8c
2 changed files with 32 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
drivers/hv/vmbus_drv.c
View File

@@ -1611,18 +1611,18 @@ 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;
lockdep_assert_cpus_held();
lockdep_assert_held(&vmbus_connection.channel_mutex);
if (vmbus_proto_version < VERSION_WIN10_V4_1)
return -EIO;
if (sscanf(buf, "%uu", &target_cpu) != 1)
return -EIO;
/* Validate target_cpu for the cpumask_test_cpu() operation below. */
if (target_cpu >= nr_cpumask_bits)
return -EINVAL;
@@ -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);

1
include/linux/hyperv.h
View File

@@ -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 *