uio_hv_generic: Query the ringbuffer size for device

Query the ring buffer size from pre defined table per device
and use that value for allocating the ring buffer for that
device. Keep the size as current default which is 2 MB if
the device doesn't have any preferred ring size.
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Link: https://lore.kernel.org/r/1711788723-8593-3-git-send-email-ssengar@linux.microsoft.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/uio/uio_hv_generic.c

@@ -238,6 +238,7 @@ hv_uio_probe(struct hv_device *dev,
 	struct hv_uio_private_data *pdata;
 	void *ring_buffer;
 	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) {
@@ -245,12 +246,14 @@ hv_uio_probe(struct hv_device *dev,
 		return -ENOTSUPP;
 	}
 
+	if (!ring_size)
+		ring_size = HV_RING_SIZE * PAGE_SIZE;
+
 	pdata = devm_kzalloc(&dev->device, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return -ENOMEM;
 
-	ret = vmbus_alloc_ring(channel, HV_RING_SIZE * PAGE_SIZE,
-			       HV_RING_SIZE * PAGE_SIZE);
+	ret = vmbus_alloc_ring(channel, ring_size, ring_size);
 	if (ret)
 		return ret;