Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio update from Rusty Russell:
 "Some nice cleanups, and even a patch my wife did as a "live" demo for
  Latinoware 2012.

  There's a slightly non-trivial merge in virtio-net, as we cleaned up
  the virtio add_buf interface while DaveM accepted the mq virtio-net
  patches."

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (27 commits)
  virtio_console: Add support for remoteproc serial
  virtio_console: Merge struct buffer_token into struct port_buffer
  virtio: add drv_to_virtio to make code clearly
  virtio: use dev_to_virtio wrapper in virtio
  virtio-mmio: Fix irq parsing in command line parameter
  virtio_console: Free buffers from out-queue upon close
  virtio: Convert dev_printk(KERN_<LEVEL> to dev_<level>(
  virtio_console: Use kmalloc instead of kzalloc
  virtio_console: Free buffer if splice fails
  virtio: tools: make it clear that virtqueue_add_buf() no longer returns > 0
  virtio: scsi: make it clear that virtqueue_add_buf() no longer returns > 0
  virtio: rpmsg: make it clear that virtqueue_add_buf() no longer returns > 0
  virtio: net: make it clear that virtqueue_add_buf() no longer returns > 0
  virtio: console: make it clear that virtqueue_add_buf() no longer returns > 0
  virtio: make virtqueue_add_buf() returning 0 on success, not capacity.
  virtio: console: don't rely on virtqueue_add_buf() returning capacity.
  virtio_net: don't rely on virtqueue_add_buf() returning capacity.
  virtio-net: remove unused skb_vnet_hdr->num_sg field
  virtio-net: correct capacity math on ring full
  virtio: move queue_index and num_free fields into core struct virtqueue.
  ...

17 files changed, 412 insertions, 276 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 90493d4ead1f..c594cb16c37b 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -37,8 +37,12 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/kconfig.h>
 #include "../tty/hvc/hvc_console.h"
 
+#define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
+
 /*
  * This is a global struct for storing common data for all the devices
  * this driver handles.
@@ -111,6 +115,21 @@ struct port_buffer {
         size_t len;
         /* offset in the buf from which to consume data */
         size_t offset;
+
+        /* DMA address of buffer */
+        dma_addr_t dma;
+
+        /* Device we got DMA memory from */
+        struct device *dev;
+
+        /* List of pending dma buffers to free */
+        struct list_head list;
+
+        /* If sgpages == 0 then buf is used */
+        unsigned int sgpages;
+
+        /* sg is used if spages > 0. sg must be the last in is struct */
+        struct scatterlist sg[0];
 };
 
 /*
@@ -325,6 +344,11 @@ static bool is_console_port(struct port *port)
         return false;
 }
 
+static bool is_rproc_serial(const struct virtio_device *vdev)
+{
+        return is_rproc_enabled && vdev->id.device == VIRTIO_ID_RPROC_SERIAL;
+}
+
 static inline bool use_multiport(struct ports_device *portdev)
 {
         /*
@@ -336,20 +360,110 @@ static inline bool use_multiport(struct ports_device *portdev)
         return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
 }
 
-static void free_buf(struct port_buffer *buf)
+static DEFINE_SPINLOCK(dma_bufs_lock);
+static LIST_HEAD(pending_free_dma_bufs);
+
+static void free_buf(struct port_buffer *buf, bool can_sleep)
 {
-        kfree(buf->buf);
+        unsigned int i;
+
+        for (i = 0; i < buf->sgpages; i++) {
+                struct page *page = sg_page(&buf->sg[i]);
+                if (!page)
+                        break;
+                put_page(page);
+        }
+
+        if (!buf->dev) {
+                kfree(buf->buf);
+        } else if (is_rproc_enabled) {
+                unsigned long flags;
+
+                /* dma_free_coherent requires interrupts to be enabled. */
+                if (!can_sleep) {
+                        /* queue up dma-buffers to be freed later */
+                        spin_lock_irqsave(&dma_bufs_lock, flags);
+                        list_add_tail(&buf->list, &pending_free_dma_bufs);
+                        spin_unlock_irqrestore(&dma_bufs_lock, flags);
+                        return;
+                }
+                dma_free_coherent(buf->dev, buf->size, buf->buf, buf->dma);
+
+                /* Release device refcnt and allow it to be freed */
+                put_device(buf->dev);
+        }
+
         kfree(buf);
 }
 
-static struct port_buffer *alloc_buf(size_t buf_size)
+static void reclaim_dma_bufs(void)
+{
+        unsigned long flags;
+        struct port_buffer *buf, *tmp;
+        LIST_HEAD(tmp_list);
+
+        if (list_empty(&pending_free_dma_bufs))
+                return;
+
+        /* Create a copy of the pending_free_dma_bufs while holding the lock */
+        spin_lock_irqsave(&dma_bufs_lock, flags);
+        list_cut_position(&tmp_list, &pending_free_dma_bufs,
+                          pending_free_dma_bufs.prev);
+        spin_unlock_irqrestore(&dma_bufs_lock, flags);
+
+        /* Release the dma buffers, without irqs enabled */
+        list_for_each_entry_safe(buf, tmp, &tmp_list, list) {
+                list_del(&buf->list);
+                free_buf(buf, true);
+        }
+}
+
+static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
+                                     int pages)
 {
         struct port_buffer *buf;
 
-        buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+        reclaim_dma_bufs();
+
+        /*
+         * Allocate buffer and the sg list. The sg list array is allocated
+         * directly after the port_buffer struct.
+         */
+        buf = kmalloc(sizeof(*buf) + sizeof(struct scatterlist) * pages,
+                      GFP_KERNEL);
         if (!buf)
                 goto fail;
-        buf->buf = kzalloc(buf_size, GFP_KERNEL);
+
+        buf->sgpages = pages;
+        if (pages > 0) {
+                buf->dev = NULL;
+                buf->buf = NULL;
+                return buf;
+        }
+
+        if (is_rproc_serial(vq->vdev)) {
+                /*
+                 * Allocate DMA memory from ancestor. When a virtio
+                 * device is created by remoteproc, the DMA memory is
+                 * associated with the grandparent device:
+                 * vdev => rproc => platform-dev.
+                 * The code here would have been less quirky if
+                 * DMA_MEMORY_INCLUDES_CHILDREN had been supported
+                 * in dma-coherent.c
+                 */
+                if (!vq->vdev->dev.parent || !vq->vdev->dev.parent->parent)