Move host-side virtio ring functions to file virtio_ring_host.c
The functions vring_avail_desc_user(), vring_add_used_user() and
vring_next_desc() are moved from vhost.c to the new file
virtio_ring_host.c. (The functions are copied as is without any changes)
Signed-off-by: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
---
drivers/vhost/Kconfig | 2 +
drivers/vhost/vhost.c | 92 -----------------------------
drivers/virtio/Kconfig | 3 +
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio_ring_host.c | 117 +++++++++++++++++++++++++++++++++++++
include/linux/virtio_ring.h | 8 +++
6 files changed, 131 insertions(+), 92 deletions(-)
create mode 100644 drivers/virtio/virtio_ring_host.c
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index 202bba6..5bfdaa9 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -1,4 +1,6 @@
config VHOST_NET
+ select VIRTIO_RING_HOST
+ select VIRTIO
tristate "Host kernel accelerator for virtio net (EXPERIMENTAL)"
depends on NET && EVENTFD && (TUN || !TUN) && (MACVTAP || !MACVTAP) && EXPERIMENTAL
---help---
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 5e91048..6634f0a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1097,27 +1097,6 @@ static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
return ret;
}
-/* Each buffer in the virtqueues is actually a chain of descriptors. This
- * function returns the next descriptor in the chain,
- * or -1U if we're at the end. */
-unsigned vring_next_desc(struct vring_desc *desc)
-{
- unsigned int next;
-
- /* If this descriptor says it doesn't chain, we're done. */
- if (!(desc->flags & VRING_DESC_F_NEXT))
- return -1U;
-
- /* Check they're not leading us off end of descriptors. */
- next = desc->next;
- /* Make sure compiler knows to grab that: we don't want it changing! */
- /* We will use the result as an index in an array, so most
- * architectures only need a compiler barrier here. */
- read_barrier_depends();
-
- return next;
-}
-
static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
struct iovec iov[], unsigned int iov_size,
unsigned int *out_num, unsigned int *in_num,
@@ -1206,51 +1185,6 @@ static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
return 0;
}
-static int vring_avail_desc_user(struct vring_host *vh)
-{
- int head;
- u16 last_avail_idx;
-
- /* Check it isn't doing very strange things with descriptor numbers. */
- last_avail_idx = vh->last_avail_idx;
- if (unlikely(__get_user(vh->avail_idx, &vh->vr.avail->idx))) {
- pr_debug("Failed to access avail idx at %p\n",
- &vh->vr.avail->idx);
- return -EFAULT;
- }
-
- if (unlikely((u16)(vh->avail_idx - last_avail_idx) > vh->vr.num))
- return -EFAULT;
-
- /* If there's nothing new since last we looked, return invalid. */
- if (vh->avail_idx == last_avail_idx)
- return vh->vr.num;
-
- /* Only get avail ring entries after they have been exposed by guest. */
- smp_rmb();
-
- /* Grab the next descriptor number they're advertising, and increment
- * the index we've seen. */
- if (unlikely(__get_user(head,
- &vh->vr.avail->ring[last_avail_idx %
- vh->vr.num]))) {
- pr_debug("Failed to read head: idx %d address %p\n",
- last_avail_idx,
- &vh->vr.avail->ring[last_avail_idx %
- vh->vr.num]);
- return -EFAULT;
- }
-
- /* If their number is silly, that's an error. */
- if (unlikely(head >= vh->vr.num)) {
- pr_debug("Guest says index %u > %u is available",
- head, vh->vr.num);
- return -EINVAL;
- }
-
- return head;
-}
-
/* This looks in the virtqueue and for the first available buffer, and converts
* it to an iovec for convenient access. Since descriptors consist of some
* number of output then some number of input descriptors, it's actually two
@@ -1352,32 +1286,6 @@ void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
vq->hst.last_avail_idx -= n;
}
-struct vring_used_elem *vring_add_used_user(struct vring_host *vh,
- unsigned int head, int len)
-{
- struct vring_used_elem *used;
-
- /* The virtqueue contains a ring of used buffers. Get a pointer to the
- * next entry in that used ring. */
- used = &vh->vr.used->ring[vh->last_used_idx % vh->vr.num];
- if (__put_user(head, &used->id)) {
- pr_debug("Failed to write used id");
- return NULL;
- }
- if (__put_user(len, &used->len)) {
- pr_debug("Failed to write used len");
- return NULL;
- }
- /* Make sure buffer is written before we update index. */
- smp_wmb();
- if (__put_user(vh->last_used_idx + 1, &vh->vr.used->idx)) {
- pr_debug("Failed to increment used idx");
- return NULL;
- }
- vh->last_used_idx++;
- return used;
-}
-
/* After we've used one of their buffers, we tell them about it. We'll then
* want to notify the guest, using eventfd. */
int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 8d5bddb..4e72892 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -5,6 +5,9 @@ config VIRTIO
bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_LGUEST,
CONFIG_RPMSG or CONFIG_S390_GUEST.
+config VIRTIO_RING_HOST
+ tristate
+
menu "Virtio drivers"
config VIRTIO_PCI
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 9076635..54831f4 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
+obj-$(CONFIG_VIRTIO_RING_HOST) += virtio_ring_host.o
obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
diff --git a/drivers/virtio/virtio_ring_host.c b/drivers/virtio/virtio_ring_host.c
new file mode 100644
index 0000000..192b838
--- /dev/null
+++ b/drivers/virtio/virtio_ring_host.c
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2012
+ * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2006 Rusty Russell IBM Corporation
+ * Copyring
+ *
+ * Author: Sjur Brendeland / sjur.brandeland@xxxxxxxxxxxxxx
+ * Copied from vhost.c, author Michael S. Tsirkin <mst@xxxxxxxxxx>
+ *
+ * License terms: GNU General Public License (GPL) version 2.
+ *
+ * Inspiration, some code, and most witty comments come from
+ * Documentation/virtual/lguest/lguest.c, by Rusty Russell
+ *
+ * Generic code for virtio server in host kernel.
+ */
+#include <linux/virtio.h>
+#include <linux/virtio_ring.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+
+MODULE_LICENSE("GPL");
+
+struct vring_used_elem *vring_add_used_user(struct vring_host *vh,
+ unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+
+ /* The virtqueue contains a ring of used buffers. Get a pointer to the
+ * next entry in that used ring. */
+ used = &vh->vr.used->ring[vh->last_used_idx % vh->vr.num];
+ if (__put_user(head, &used->id)) {
+ pr_debug("Failed to write used id");
+ return NULL;
+ }
+ if (__put_user(len, &used->len)) {
+ pr_debug("Failed to write used len");
+ return NULL;
+ }
+ /* Make sure buffer is written before we update index. */
+ smp_wmb();
+ if (__put_user(vh->last_used_idx + 1, &vh->vr.used->idx)) {
+ pr_debug("Failed to increment used idx");
+ return NULL;
+ }
+ vh->last_used_idx++;
+ return used;
+}
+EXPORT_SYMBOL(vring_add_used_user);
+
+int vring_avail_desc_user(struct vring_host *vh)
+{
+ int head;
+ u16 last_avail_idx;
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ last_avail_idx = vh->last_avail_idx;
+ if (unlikely(__get_user(vh->avail_idx, &vh->vr.avail->idx))) {
+ pr_debug("Failed to access avail idx at %p\n",
+ &vh->vr.avail->idx);
+ return -EFAULT;
+ }
+
+ if (unlikely((u16)(vh->avail_idx - last_avail_idx) > vh->vr.num))
+ return -EFAULT;
+
+ /* If there's nothing new since last we looked, return invalid. */
+ if (vh->avail_idx == last_avail_idx)
+ return vh->vr.num;
+
+ /* Only get avail ring entries after they have been exposed by guest. */
+ smp_rmb();
+
+ /* Grab the next descriptor number they're advertising, and increment
+ * the index we've seen. */
+ if (unlikely(__get_user(head,
+ &vh->vr.avail->ring[last_avail_idx %
+ vh->vr.num]))) {
+ pr_debug("Failed to read head: idx %d address %p\n",
+ last_avail_idx,
+ &vh->vr.avail->ring[last_avail_idx %
+ vh->vr.num]);
+ return -EFAULT;
+ }
+
+ /* If their number is silly, that's an error. */
+ if (unlikely(head >= vh->vr.num)) {
+ pr_debug("Guest says index %u > %u is available",
+ head, vh->vr.num);
+ return -EINVAL;
+ }
+
+ return head;
+}
+EXPORT_SYMBOL(vring_avail_desc_user);
+
+/* Each buffer in the virtqueues is actually a chain of descriptors. This
+ * function returns the next descriptor in the chain,
+ * or -1U if we're at the end. */
+unsigned vring_next_desc(struct vring_desc *desc)
+{
+ unsigned int next;
+
+ /* If this descriptor says it doesn't chain, we're done. */
+ if (!(desc->flags & VRING_DESC_F_NEXT))
+ return -1U;
+
+ /* Check they're not leading us off end of descriptors. */
+ next = desc->next;
+ /* Make sure compiler knows to grab that: we don't want it changing! */
+ /* We will use the result as an index in an array, so most
+ * architectures only need a compiler barrier here. */
+ read_barrier_depends();
+
+ return next;
+}
+EXPORT_SYMBOL(vring_next_desc);
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 7917dac..6c9b871 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -34,4 +34,12 @@ void vring_del_virtqueue(struct virtqueue *vq);
void vring_transport_features(struct virtio_device *vdev);
irqreturn_t vring_interrupt(int irq, void *_vq);
+
+unsigned vring_next_desc(struct vring_desc *desc);
+
+int vring_avail_desc_user(struct vring_host *vh);
+
+struct vring_used_elem *vring_add_used_user(struct vring_host *vh,
+ unsigned int head, int len);
+
#endif /* _LINUX_VIRTIO_RING_H */
--
1.7.5.4
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