6.12-stable review patch. If anyone has any objections, please let me know.
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From: Long Li longli@microsoft.com
commit d062463edf1770427dc2d637df4088df4835aa47 upstream.
Hyper-V may offer a non latency sensitive device with subchannels without monitor bit enabled. The decision is entirely on the Hyper-V host not configurable within guest.
When a device has subchannels, also signal events for the subchannel if its monitor bit is disabled.
This patch also removes the memory barrier when monitor bit is enabled as it is not necessary. The memory barrier is only needed between setting up interrupt mask and calling vmbus_set_event() when monitor bit is disabled.
Signed-off-by: Long Li longli@microsoft.com Reviewed-by: Michael Kelley mhklinux@outlook.com Reviewed-by: Saurabh Sengar ssengar@linux.microsoft.com Link: https://lore.kernel.org/r/1741644721-20389-1-git-send-email-longli@linuxonhy... Fixes: 37bd91f22794 ("uio_hv_generic: Let userspace take care of interrupt mask") Cc: stable@vger.kernel.org # 6.12.x Signed-off-by: Naman Jain namjain@linux.microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/uio/uio_hv_generic.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-)
--- a/drivers/uio/uio_hv_generic.c +++ b/drivers/uio/uio_hv_generic.c @@ -65,6 +65,16 @@ struct hv_uio_private_data { char send_name[32]; };
+static void set_event(struct vmbus_channel *channel, s32 irq_state) +{ + channel->inbound.ring_buffer->interrupt_mask = !irq_state; + if (!channel->offermsg.monitor_allocated && irq_state) { + /* MB is needed for host to see the interrupt mask first */ + virt_mb(); + vmbus_set_event(channel); + } +} + /* * This is the irqcontrol callback to be registered to uio_info. * It can be used to disable/enable interrupt from user space processes. @@ -79,12 +89,15 @@ hv_uio_irqcontrol(struct uio_info *info, { struct hv_uio_private_data *pdata = info->priv; struct hv_device *dev = pdata->device; + struct vmbus_channel *primary, *sc;
- dev->channel->inbound.ring_buffer->interrupt_mask = !irq_state; - virt_mb(); + primary = dev->channel; + set_event(primary, irq_state);
- if (!dev->channel->offermsg.monitor_allocated && irq_state) - vmbus_setevent(dev->channel); + mutex_lock(&vmbus_connection.channel_mutex); + list_for_each_entry(sc, &primary->sc_list, sc_list) + set_event(sc, irq_state); + mutex_unlock(&vmbus_connection.channel_mutex);
return 0; } @@ -95,11 +108,18 @@ hv_uio_irqcontrol(struct uio_info *info, static void hv_uio_channel_cb(void *context) { struct vmbus_channel *chan = context; - struct hv_device *hv_dev = chan->device_obj; - struct hv_uio_private_data *pdata = hv_get_drvdata(hv_dev); + struct hv_device *hv_dev; + struct hv_uio_private_data *pdata;
virt_mb();
+ /* + * The callback may come from a subchannel, in which case look + * for the hv device in the primary channel + */ + hv_dev = chan->primary_channel ? + chan->primary_channel->device_obj : chan->device_obj; + pdata = hv_get_drvdata(hv_dev); uio_event_notify(&pdata->info); }