uio_hv_generic: support sub-channels
Use sysfs to allow supporting sub-channels. The userspace application makes request to host to create sub-channels and the UIO kernel driver populates the sysfs per-channel directory with a binary attribute file that can be used to read/write ring. Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -132,3 +132,10 @@ KernelVersion: 4.16
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Contact: Stephen Hemminger <sthemmin@microsoft.com>
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Contact: Stephen Hemminger <sthemmin@microsoft.com>
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Description: Monitor bit associated with channel
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Description: Monitor bit associated with channel
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Users: Debugging tools and userspace drivers
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Users: Debugging tools and userspace drivers
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What: /sys/bus/vmbus/devices/vmbus_*/channels/NN/ring
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Date: January. 2018
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KernelVersion: 4.16
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Contact: Stephen Hemminger <sthemmin@microsoft.com>
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Description: Binary file created by uio_hv_generic for ring buffer
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Users: Userspace drivers
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@ -709,6 +709,11 @@ The vmbus device regions are mapped into uio device resources:
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3) Network receive buffer region
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3) Network receive buffer region
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4) Network send buffer region
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4) Network send buffer region
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If a subchannel is created by a request to host, then the uio_hv_generic
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device driver will create a sysfs binary file for the per-channel ring buffer.
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For example:
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/sys/bus/vmbus/devices/3811fe4d-0fa0-4b62-981a-74fc1084c757/channels/21/ring
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Further information
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Further information
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===================
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===================
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@ -121,6 +121,94 @@ static void hv_uio_rescind(struct vmbus_channel *channel)
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uio_event_notify(&pdata->info);
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uio_event_notify(&pdata->info);
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}
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}
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/*
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* Handle fault when looking for sub channel ring buffer
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* Subchannel ring buffer is same as resource 0 which is main ring buffer
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* This is derived from uio_vma_fault
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*/
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static int hv_uio_vma_fault(struct vm_fault *vmf)
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{
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struct vm_area_struct *vma = vmf->vma;
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void *ring_buffer = vma->vm_private_data;
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struct page *page;
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void *addr;
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addr = ring_buffer + (vmf->pgoff << PAGE_SHIFT);
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page = virt_to_page(addr);
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get_page(page);
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vmf->page = page;
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return 0;
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}
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static const struct vm_operations_struct hv_uio_vm_ops = {
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.fault = hv_uio_vma_fault,
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};
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/* Sysfs API to allow mmap of the ring buffers */
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static int hv_uio_ring_mmap(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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struct vm_area_struct *vma)
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{
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struct vmbus_channel *channel
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= container_of(kobj, struct vmbus_channel, kobj);
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unsigned long requested_pages, actual_pages;
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if (vma->vm_end < vma->vm_start)
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return -EINVAL;
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/* only allow 0 for now */
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if (vma->vm_pgoff > 0)
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return -EINVAL;
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requested_pages = vma_pages(vma);
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actual_pages = 2 * HV_RING_SIZE;
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if (requested_pages > actual_pages)
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return -EINVAL;
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vma->vm_private_data = channel->ringbuffer_pages;
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vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
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vma->vm_ops = &hv_uio_vm_ops;
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return 0;
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}
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static struct bin_attribute ring_buffer_bin_attr __ro_after_init = {
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.attr = {
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.name = "ring",
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.mode = 0600,
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/* size is set at init time */
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},
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.mmap = hv_uio_ring_mmap,
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};
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/* Callback from VMBUS subystem when new channel created. */
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static void
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hv_uio_new_channel(struct vmbus_channel *new_sc)
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{
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struct hv_device *hv_dev = new_sc->primary_channel->device_obj;
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struct device *device = &hv_dev->device;
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struct hv_uio_private_data *pdata = hv_get_drvdata(hv_dev);
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const size_t ring_bytes = HV_RING_SIZE * PAGE_SIZE;
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int ret;
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/* Create host communication ring */
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ret = vmbus_open(new_sc, ring_bytes, ring_bytes, NULL, 0,
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hv_uio_channel_cb, pdata);
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if (ret) {
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dev_err(device, "vmbus_open subchannel failed: %d\n", ret);
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return;
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}
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/* Disable interrupts on sub channel */
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new_sc->inbound.ring_buffer->interrupt_mask = 1;
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set_channel_read_mode(new_sc, HV_CALL_ISR);
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ret = sysfs_create_bin_file(&new_sc->kobj, &ring_buffer_bin_attr);
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if (ret) {
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dev_err(device, "sysfs create ring bin file failed; %d\n", ret);
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vmbus_close(new_sc);
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}
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}
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static void
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static void
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hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata)
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hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata)
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{
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{
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@ -236,6 +324,7 @@ hv_uio_probe(struct hv_device *dev,
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}
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}
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vmbus_set_chn_rescind_callback(dev->channel, hv_uio_rescind);
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vmbus_set_chn_rescind_callback(dev->channel, hv_uio_rescind);
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vmbus_set_sc_create_callback(dev->channel, hv_uio_new_channel);
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hv_set_drvdata(dev, pdata);
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hv_set_drvdata(dev, pdata);
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