RE: [PATCH 3/6] uio_hv_generic: Enable interrupt for low speed VMBus devices

Long Li
2024-03-12T20:59:52Z

> Subject: [PATCH 3/6] uio_hv_generic: Enable interrupt for low speed VMBus
> devices
>
> Hyper-V is adding some "specialty" synthetic devices. Instead of writing new
> kernel-level VMBus drivers for these devices, the devices will be presented to
> user space via this existing Hyper-V generic UIO driver, so that a user space driver
> can handle the device. Since these new synthetic devices are low speed devices,
> they don't support monitor bits and we must use vmbus_setevent() to enable
> interrupts from the host.
>
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>

Reviewed-by: Long Li <longli@microsoft.com>

> ---
> drivers/uio/uio_hv_generic.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c index
> 4bda6b52e49e..289611c7dfd7 100644
> --- a/drivers/uio/uio_hv_generic.c
> +++ b/drivers/uio/uio_hv_generic.c
> @@ -84,6 +84,9 @@ hv_uio_irqcontrol(struct uio_info *info, s32 irq_state)
> dev->channel->inbound.ring_buffer->interrupt_mask = !irq_state;
> virt_mb();
>
> + if (!dev->channel->offermsg.monitor_allocated && irq_state)
> + vmbus_setevent(dev->channel);
> +
> return 0;
> }
>
> @@ -240,12 +243,6 @@ hv_uio_probe(struct hv_device *dev,
> int ret;
> size_t ring_size = hv_dev_ring_size(channel);
>
> - /* Communicating with host has to be via shared memory not hypercall
> */
> - if (!channel->offermsg.monitor_allocated) {
> - dev_err(&dev->device, "vmbus channel requires hypercall\n");
> - return -ENOTSUPP;
> - }
> -
> if (!ring_size)
> ring_size = HV_RING_SIZE * PAGE_SIZE;
>
> --
> 2.34.1
>