vmbus: keep pointer to ring buffer page

Avoid going from struct page to virt address (and back) by just
keeping pointer to the allocated pages instead of virt address.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/channel.c

@@ -91,11 +91,14 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
 	unsigned long flags;
 	int ret, err = 0;
 	struct page *page;
+	unsigned int order;
 
 	if (send_ringbuffer_size % PAGE_SIZE ||
 	    recv_ringbuffer_size % PAGE_SIZE)
 		return -EINVAL;
 
+	order = get_order(send_ringbuffer_size + recv_ringbuffer_size);
+
 	spin_lock_irqsave(&newchannel->lock, flags);
 	if (newchannel->state == CHANNEL_OPEN_STATE) {
 		newchannel->state = CHANNEL_OPENING_STATE;
@@ -110,21 +113,17 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
 
 	/* Allocate the ring buffer */
 	page = alloc_pages_node(cpu_to_node(newchannel->target_cpu),
-				GFP_KERNEL|__GFP_ZERO,
-				get_order(send_ringbuffer_size +
-				recv_ringbuffer_size));
+				GFP_KERNEL|__GFP_ZERO, order);
 
 	if (!page)
-		page = alloc_pages(GFP_KERNEL|__GFP_ZERO,
-				   get_order(send_ringbuffer_size +
-					     recv_ringbuffer_size));
+		page = alloc_pages(GFP_KERNEL|__GFP_ZERO, order);
 
 	if (!page) {
 		err = -ENOMEM;
 		goto error_set_chnstate;
 	}
 
-	newchannel->ringbuffer_pages = page_address(page);
+	newchannel->ringbuffer_page = page;
 	newchannel->ringbuffer_pagecount = (send_ringbuffer_size +
 					   recv_ringbuffer_size) >> PAGE_SHIFT;
 
@@ -239,8 +238,7 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
 error_free_pages:
 	hv_ringbuffer_cleanup(&newchannel->outbound);
 	hv_ringbuffer_cleanup(&newchannel->inbound);
-	__free_pages(page,
-		     get_order(send_ringbuffer_size + recv_ringbuffer_size));
+	__free_pages(page, order);
 error_set_chnstate:
 	newchannel->state = CHANNEL_OPEN_STATE;
 	return err;
@@ -658,8 +656,8 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
 	hv_ringbuffer_cleanup(&channel->outbound);
 	hv_ringbuffer_cleanup(&channel->inbound);
 
-	free_pages((unsigned long)channel->ringbuffer_pages,
-		get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
+	__free_pages(channel->ringbuffer_page,
+		     get_order(channel->ringbuffer_pagecount << PAGE_SHIFT));
 
 out:
 	return ret;

drivers/uio/uio_hv_generic.c

@@ -130,11 +130,12 @@ static int hv_uio_ring_mmap(struct file *filp, struct kobject *kobj,
 		= container_of(kobj, struct vmbus_channel, kobj);
 	struct hv_device *dev = channel->primary_channel->device_obj;
 	u16 q_idx = channel->offermsg.offer.sub_channel_index;
+	void *ring_buffer = page_address(channel->ringbuffer_page);
 
 	dev_dbg(&dev->device, "mmap channel %u pages %#lx at %#lx\n",
 		q_idx, vma_pages(vma), vma->vm_pgoff);
 
-	return vm_iomap_memory(vma, virt_to_phys(channel->ringbuffer_pages),
+	return vm_iomap_memory(vma, virt_to_phys(ring_buffer),
 			       channel->ringbuffer_pagecount << PAGE_SHIFT);
 }
 
@@ -223,7 +224,7 @@ hv_uio_probe(struct hv_device *dev,
 	/* mem resources */
 	pdata->info.mem[TXRX_RING_MAP].name = "txrx_rings";
 	pdata->info.mem[TXRX_RING_MAP].addr
-		= (uintptr_t)dev->channel->ringbuffer_pages;
+		= (uintptr_t)page_address(dev->channel->ringbuffer_page);
 	pdata->info.mem[TXRX_RING_MAP].size
 		= dev->channel->ringbuffer_pagecount << PAGE_SHIFT;
 	pdata->info.mem[TXRX_RING_MAP].memtype = UIO_MEM_LOGICAL;

include/linux/hyperv.h

@@ -739,7 +739,7 @@ struct vmbus_channel {
 	u32 ringbuffer_gpadlhandle;
 
 	/* Allocated memory for ring buffer */
-	void *ringbuffer_pages;
+	struct page *ringbuffer_page;
 	u32 ringbuffer_pagecount;
 	struct hv_ring_buffer_info outbound;	/* send to parent */
 	struct hv_ring_buffer_info inbound;	/* receive from parent */