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>
This commit is contained in:
Stephen Hemminger 2018-02-05 10:40:27 -08:00 committed by Greg Kroah-Hartman
parent cf21be919c
commit 37b96a4931
3 changed files with 101 additions and 0 deletions

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@ -132,3 +132,10 @@ KernelVersion: 4.16
Contact: Stephen Hemminger <sthemmin@microsoft.com>
Description: Monitor bit associated with channel
Users: Debugging tools and userspace drivers
What: /sys/bus/vmbus/devices/vmbus_*/channels/NN/ring
Date: January. 2018
KernelVersion: 4.16
Contact: Stephen Hemminger <sthemmin@microsoft.com>
Description: Binary file created by uio_hv_generic for ring buffer
Users: Userspace drivers

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@ -709,6 +709,11 @@ The vmbus device regions are mapped into uio device resources:
3) Network receive buffer region
4) Network send buffer region
If a subchannel is created by a request to host, then the uio_hv_generic
device driver will create a sysfs binary file for the per-channel ring buffer.
For example:
/sys/bus/vmbus/devices/3811fe4d-0fa0-4b62-981a-74fc1084c757/channels/21/ring
Further information
===================

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@ -121,6 +121,94 @@ static void hv_uio_rescind(struct vmbus_channel *channel)
uio_event_notify(&pdata->info);
}
/*
* Handle fault when looking for sub channel ring buffer
* Subchannel ring buffer is same as resource 0 which is main ring buffer
* This is derived from uio_vma_fault
*/
static int hv_uio_vma_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
void *ring_buffer = vma->vm_private_data;
struct page *page;
void *addr;
addr = ring_buffer + (vmf->pgoff << PAGE_SHIFT);
page = virt_to_page(addr);
get_page(page);
vmf->page = page;
return 0;
}
static const struct vm_operations_struct hv_uio_vm_ops = {
.fault = hv_uio_vma_fault,
};
/* Sysfs API to allow mmap of the ring buffers */
static int hv_uio_ring_mmap(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
struct vm_area_struct *vma)
{
struct vmbus_channel *channel
= container_of(kobj, struct vmbus_channel, kobj);
unsigned long requested_pages, actual_pages;
if (vma->vm_end < vma->vm_start)
return -EINVAL;
/* only allow 0 for now */
if (vma->vm_pgoff > 0)
return -EINVAL;
requested_pages = vma_pages(vma);
actual_pages = 2 * HV_RING_SIZE;
if (requested_pages > actual_pages)
return -EINVAL;
vma->vm_private_data = channel->ringbuffer_pages;
vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = &hv_uio_vm_ops;
return 0;
}
static struct bin_attribute ring_buffer_bin_attr __ro_after_init = {
.attr = {
.name = "ring",
.mode = 0600,
/* size is set at init time */
},
.mmap = hv_uio_ring_mmap,
};
/* Callback from VMBUS subystem when new channel created. */
static void
hv_uio_new_channel(struct vmbus_channel *new_sc)
{
struct hv_device *hv_dev = new_sc->primary_channel->device_obj;
struct device *device = &hv_dev->device;
struct hv_uio_private_data *pdata = hv_get_drvdata(hv_dev);
const size_t ring_bytes = HV_RING_SIZE * PAGE_SIZE;
int ret;
/* Create host communication ring */
ret = vmbus_open(new_sc, ring_bytes, ring_bytes, NULL, 0,
hv_uio_channel_cb, pdata);
if (ret) {
dev_err(device, "vmbus_open subchannel failed: %d\n", ret);
return;
}
/* Disable interrupts on sub channel */
new_sc->inbound.ring_buffer->interrupt_mask = 1;
set_channel_read_mode(new_sc, HV_CALL_ISR);
ret = sysfs_create_bin_file(&new_sc->kobj, &ring_buffer_bin_attr);
if (ret) {
dev_err(device, "sysfs create ring bin file failed; %d\n", ret);
vmbus_close(new_sc);
}
}
static void
hv_uio_cleanup(struct hv_device *dev, struct hv_uio_private_data *pdata)
{
@ -236,6 +324,7 @@ hv_uio_probe(struct hv_device *dev,
}
vmbus_set_chn_rescind_callback(dev->channel, hv_uio_rescind);
vmbus_set_sc_create_callback(dev->channel, hv_uio_new_channel);
hv_set_drvdata(dev, pdata);