Re: [PATCH v6 6/9] virtio: Add improved queue allocation API

From: Michael S. Tsirkin
Date: Tue Feb 02 2016 - 06:25:25 EST

Next message: Marc Zyngier: "Re: [PATCH v2 14/21] arm64: KVM: VHE: Implement VHE activate/deactivate_traps"
Previous message: Juri Lelli: "Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups"
In reply to: Andy Lutomirski: "[PATCH v6 6/9] virtio: Add improved queue allocation API"
Next in thread: Andy Lutomirski: "Re: [PATCH v6 6/9] virtio: Add improved queue allocation API"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Mon, Feb 01, 2016 at 10:00:56AM -0800, Andy Lutomirski wrote:
> 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@xxxxxxxxxx>
> ---
> 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);

I think that we should teach this one to use regular kmalloc
if vring_use_dma_api is cleared.
Not a must but it seems cleaner at this stage.

> + 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

Next message: Marc Zyngier: "Re: [PATCH v2 14/21] arm64: KVM: VHE: Implement VHE activate/deactivate_traps"
Previous message: Juri Lelli: "Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups"
In reply to: Andy Lutomirski: "[PATCH v6 6/9] virtio: Add improved queue allocation API"
Next in thread: Andy Lutomirski: "Re: [PATCH v6 6/9] virtio: Add improved queue allocation API"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]