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Message-Id: <5819fe5f70a5c110ab4ea58233004aafd9259d29.1454349471.git.luto@kernel.org>
Date: Mon, 1 Feb 2016 10:00:56 -0800
From: Andy Lutomirski <luto@...nel.org>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
David Woodhouse <dwmw2@...radead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
sparclinux@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
Christian Borntraeger <borntraeger@...ibm.com>,
Cornelia Huck <cornelia.huck@...ibm.com>,
Sebastian Ott <sebott@...ux.vnet.ibm.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Christoph Hellwig <hch@....de>, KVM <kvm@...r.kernel.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
linux-s390 <linux-s390@...r.kernel.org>,
Linux Virtualization <virtualization@...ts.linux-foundation.org>,
David Vrabel <david.vrabel@...rix.com>,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
xen-devel@...ts.xenproject.org, Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v6 6/9] virtio: Add improved queue allocation API
This leaves vring_new_virtqueue alone for compatbility, but it
adds two new improved APIs:
vring_create_virtqueue: Creates a virtqueue backed by automatically
allocated coherent memory. (Some day it this could be extended to
support non-coherent memory, too, if there ends up being a platform
on which it's worthwhile.)
__vring_new_virtqueue: Creates a virtqueue with a manually-specified
layout. This should allow mic_virtio to work much more cleanly.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
drivers/virtio/virtio_ring.c | 178 +++++++++++++++++++++++++++++++++++--------
include/linux/virtio.h | 23 +++++-
include/linux/virtio_ring.h | 35 +++++++++
3 files changed, 204 insertions(+), 32 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 2f621e96b9ff..cf2840c7e500 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -95,6 +95,11 @@ struct vring_virtqueue {
/* How to notify other side. FIXME: commonalize hcalls! */
bool (*notify)(struct virtqueue *vq);
+ /* DMA, allocation, and size information */
+ bool we_own_ring;
+ size_t queue_size_in_bytes;
+ dma_addr_t queue_dma_addr;
+
#ifdef DEBUG
/* They're supposed to lock for us. */
unsigned int in_use;
@@ -878,36 +883,31 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
}
EXPORT_SYMBOL_GPL(vring_interrupt);
-struct virtqueue *vring_new_virtqueue(unsigned int index,
- unsigned int num,
- unsigned int vring_align,
- struct virtio_device *vdev,
- bool weak_barriers,
- void *pages,
- bool (*notify)(struct virtqueue *),
- void (*callback)(struct virtqueue *),
- const char *name)
+struct virtqueue *__vring_new_virtqueue(unsigned int index,
+ struct vring vring,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool (*notify)(struct virtqueue *),
+ void (*callback)(struct virtqueue *),
+ const char *name)
{
- struct vring_virtqueue *vq;
unsigned int i;
+ struct vring_virtqueue *vq;
- /* We assume num is a power of 2. */
- if (num & (num - 1)) {
- dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
- return NULL;
- }
-
- vq = kmalloc(sizeof(*vq) + num * sizeof(struct vring_desc_state),
+ vq = kmalloc(sizeof(*vq) + vring.num * sizeof(struct vring_desc_state),
GFP_KERNEL);
if (!vq)
return NULL;
- vring_init(&vq->vring, num, pages, vring_align);
+ vq->vring = vring;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
- vq->vq.num_free = num;
+ vq->vq.num_free = vring.num;
vq->vq.index = index;
+ vq->we_own_ring = false;
+ vq->queue_dma_addr = 0;
+ vq->queue_size_in_bytes = 0;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
vq->broken = false;
@@ -932,18 +932,105 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
/* Put everything in free lists. */
vq->free_head = 0;
- for (i = 0; i < num-1; i++)
+ for (i = 0; i < vring.num-1; i++)
vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
- memset(vq->desc_state, 0, num * sizeof(struct vring_desc_state));
+ memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state));
return &vq->vq;
}
+EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
+
+struct virtqueue *vring_create_virtqueue(
+ unsigned int index,
+ unsigned int num,
+ unsigned int vring_align,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool may_reduce_num,
+ bool (*notify)(struct virtqueue *),
+ void (*callback)(struct virtqueue *),
+ const char *name)
+{
+ struct virtqueue *vq;
+ void *queue;
+ dma_addr_t dma_addr;
+ size_t queue_size_in_bytes;
+ struct vring vring;
+
+ /* We assume num is a power of 2. */
+ if (num & (num - 1)) {
+ dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
+ return NULL;
+ }
+
+ /* TODO: allocate each queue chunk individually */
+ for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
+ queue = dma_zalloc_coherent(
+ vdev->dev.parent, vring_size(num, vring_align),
+ &dma_addr, GFP_KERNEL|__GFP_NOWARN);
+ if (queue)
+ break;
+ }
+
+ if (!num)
+ return NULL;
+
+ if (!queue) {
+ /* Try to get a single page. You are my only hope! */
+ queue = dma_zalloc_coherent(
+ vdev->dev.parent, vring_size(num, vring_align),
+ &dma_addr, GFP_KERNEL);
+ }
+ if (!queue)
+ return NULL;
+
+ queue_size_in_bytes = vring_size(num, vring_align);
+ vring_init(&vring, num, queue, vring_align);
+
+ vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+ notify, callback, name);
+ if (!vq) {
+ dma_free_coherent(vdev->dev.parent,
+ queue_size_in_bytes, queue,
+ dma_addr);
+ return NULL;
+ }
+
+ to_vvq(vq)->queue_dma_addr = dma_addr;
+ to_vvq(vq)->queue_size_in_bytes = queue_size_in_bytes;
+ to_vvq(vq)->we_own_ring = true;
+
+ return vq;
+}
+EXPORT_SYMBOL_GPL(vring_create_virtqueue);
+
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+ unsigned int num,
+ unsigned int vring_align,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ void *pages,
+ bool (*notify)(struct virtqueue *vq),
+ void (*callback)(struct virtqueue *vq),
+ const char *name)
+{
+ struct vring vring;
+ vring_init(&vring, num, pages, vring_align);
+ return __vring_new_virtqueue(index, vring, vdev, weak_barriers,
+ notify, callback, name);
+}
EXPORT_SYMBOL_GPL(vring_new_virtqueue);
-void vring_del_virtqueue(struct virtqueue *vq)
+void vring_del_virtqueue(struct virtqueue *_vq)
{
- list_del(&vq->list);
- kfree(to_vvq(vq));
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ if (vq->we_own_ring) {
+ dma_free_coherent(vring_dma_dev(vq), vq->queue_size_in_bytes,
+ vq->vring.desc, vq->queue_dma_addr);
+ }
+ list_del(&_vq->list);
+ kfree(vq);
}
EXPORT_SYMBOL_GPL(vring_del_virtqueue);
@@ -1007,20 +1094,51 @@ void virtio_break_device(struct virtio_device *dev)
}
EXPORT_SYMBOL_GPL(virtio_break_device);
-void *virtqueue_get_avail(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ BUG_ON(!vq->we_own_ring);
+
+ if (vring_use_dma_api(vq))
+ return vq->queue_dma_addr;
+ else
+ return virt_to_phys(vq->vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
+
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
- return vq->vring.avail;
+ BUG_ON(!vq->we_own_ring);
+
+ if (vring_use_dma_api(vq))
+ return vq->queue_dma_addr +
+ ((char *)vq->vring.avail - (char *)vq->vring.desc);
+ else
+ return virt_to_phys(vq->vring.avail);
}
-EXPORT_SYMBOL_GPL(virtqueue_get_avail);
+EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
-void *virtqueue_get_used(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
- return vq->vring.used;
+ BUG_ON(!vq->we_own_ring);
+
+ if (vring_use_dma_api(vq))
+ return vq->queue_dma_addr +
+ ((char *)vq->vring.used - (char *)vq->vring.desc);
+ else
+ return virt_to_phys(vq->vring.used);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
+
+const struct vring *virtqueue_get_vring(struct virtqueue *vq)
+{
+ return &to_vvq(vq)->vring;
}
-EXPORT_SYMBOL_GPL(virtqueue_get_used);
+EXPORT_SYMBOL_GPL(virtqueue_get_vring);
MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 8f4d4bfa6d46..d5eb5479a425 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -75,8 +75,27 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
bool virtqueue_is_broken(struct virtqueue *vq);
-void *virtqueue_get_avail(struct virtqueue *vq);
-void *virtqueue_get_used(struct virtqueue *vq);
+const struct vring *virtqueue_get_vring(struct virtqueue *vq);
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
+
+/*
+ * Legacy accessors -- in almost all cases, these are the wrong functions
+ * to use.
+ */
+static inline void *virtqueue_get_desc(struct virtqueue *vq)
+{
+ return virtqueue_get_vring(vq)->desc;
+}
+static inline void *virtqueue_get_avail(struct virtqueue *vq)
+{
+ return virtqueue_get_vring(vq)->avail;
+}
+static inline void *virtqueue_get_used(struct virtqueue *vq)
+{
+ return virtqueue_get_vring(vq)->used;
+}
/**
* virtio_device - representation of a device using virtio
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index a156e2b6ccfe..e8d36938f09a 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -59,6 +59,35 @@ static inline void virtio_store_mb(bool weak_barriers,
struct virtio_device;
struct virtqueue;
+/*
+ * Creates a virtqueue and allocates the descriptor ring. If
+ * may_reduce_num is set, then this may allocate a smaller ring than
+ * expected. The caller should query virtqueue_get_ring_size to learn
+ * the actual size of the ring.
+ */
+struct virtqueue *vring_create_virtqueue(unsigned int index,
+ unsigned int num,
+ unsigned int vring_align,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool may_reduce_num,
+ bool (*notify)(struct virtqueue *vq),
+ void (*callback)(struct virtqueue *vq),
+ const char *name);
+
+/* Creates a virtqueue with a custom layout. */
+struct virtqueue *__vring_new_virtqueue(unsigned int index,
+ struct vring vring,
+ struct virtio_device *vdev,
+ bool weak_barriers,
+ bool (*notify)(struct virtqueue *),
+ void (*callback)(struct virtqueue *),
+ const char *name);
+
+/*
+ * Creates a virtqueue with a standard layout but a caller-allocated
+ * ring.
+ */
struct virtqueue *vring_new_virtqueue(unsigned int index,
unsigned int num,
unsigned int vring_align,
@@ -68,7 +97,13 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),
const char *name);
+
+/*
+ * Destroys a virtqueue. If created with vring_create_virtqueue, this
+ * also frees the ring.
+ */
void vring_del_virtqueue(struct virtqueue *vq);
+
/* Filter out transport-specific feature bits. */
void vring_transport_features(struct virtio_device *vdev);
--
2.5.0
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