From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: [PATCH 9/9] virtio: reimplement virtqueue_add_buf using new functions Date: Tue, 12 Feb 2013 13:23:35 +0100 Message-ID: <1360671815-2135-10-git-send-email-pbonzini__8470.95396970889$1360671921$gmane$org@redhat.com> References: <1360671815-2135-1-git-send-email-pbonzini@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1360671815-2135-1-git-send-email-pbonzini@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, mst@redhat.com, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org Eliminate the code duplication between virtqueue_add_buf and virtqueue_add_sg. That's safe to do now that no devices will pass scatterlists with a termination marker in the middle. Signed-off-by: Paolo Bonzini --- drivers/virtio/virtio_ring.c | 159 +++--------------------------------------- 1 files changed, 11 insertions(+), 148 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index b803cf7..71488c5 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -123,63 +123,6 @@ struct vring_virtqueue #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) -/* Set up an indirect table of descriptors and add it to the queue. */ -static int vring_add_indirect(struct vring_virtqueue *vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - gfp_t gfp) -{ - struct vring_desc *desc; - unsigned head; - int i; - - /* - * We require lowmem mappings for the descriptors because - * otherwise virt_to_phys will give us bogus addresses in the - * virtqueue. - */ - gfp &= ~(__GFP_HIGHMEM | __GFP_HIGH); - - desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); - if (!desc) - return -ENOMEM; - - /* Transfer entries from the sg list into the indirect page */ - for (i = 0; i < out; i++) { - desc[i].flags = VRING_DESC_F_NEXT; - desc[i].addr = sg_phys(sg); - desc[i].len = sg->length; - desc[i].next = i+1; - sg++; - } - for (; i < (out + in); i++) { - desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; - desc[i].addr = sg_phys(sg); - desc[i].len = sg->length; - desc[i].next = i+1; - sg++; - } - - /* Last one doesn't continue. */ - desc[i-1].flags &= ~VRING_DESC_F_NEXT; - desc[i-1].next = 0; - - /* We're about to use a buffer */ - vq->vq.num_free--; - - /* Use a single buffer which doesn't continue */ - head = vq->free_head; - vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT; - vq->vring.desc[head].addr = virt_to_phys(desc); - vq->vring.desc[head].len = i * sizeof(struct vring_desc); - - /* Update free pointer */ - vq->free_head = vq->vring.desc[head].next; - - return head; -} - /** * virtqueue_add_buf_single - expose a single scatterlist entry to other end * @vq: the struct virtqueue we're talking about. @@ -234,104 +177,25 @@ EXPORT_SYMBOL_GPL(virtqueue_add_buf_single); * * Returns zero or a negative error (ie. ENOSPC, ENOMEM). */ -int virtqueue_add_buf(struct virtqueue *_vq, +int virtqueue_add_buf(struct virtqueue *vq, struct scatterlist sg[], unsigned int out, unsigned int in, void *data, gfp_t gfp) { - struct vring_virtqueue *vq = to_vvq(_vq); - unsigned int i, avail, uninitialized_var(prev); - int head; - - START_USE(vq); - - BUG_ON(data == NULL); - -#ifdef DEBUG - { - ktime_t now = ktime_get(); - - /* No kick or get, with .1 second between? Warn. */ - if (vq->last_add_time_valid) - WARN_ON(ktime_to_ms(ktime_sub(now, vq->last_add_time)) - > 100); - vq->last_add_time = now; - vq->last_add_time_valid = true; - } -#endif - - /* If the host supports indirect descriptor tables, and we have multiple - * buffers, then go indirect. FIXME: tune this threshold */ - if (vq->indirect && (out + in) > 1 && vq->vq.num_free) { - head = vring_add_indirect(vq, sg, out, in, gfp); - if (likely(head >= 0)) - goto add_head; - } - - BUG_ON(out + in > vq->vring.num); - BUG_ON(out + in == 0); - - if (vq->vq.num_free < out + in) { - pr_debug("Can't add buf len %i - avail = %i\n", - out + in, vq->vq.num_free); - /* FIXME: for historical reasons, we force a notify here if - * there are outgoing parts to the buffer. Presumably the - * host should service the ring ASAP. */ - if (out) - vq->notify(&vq->vq); - END_USE(vq); - return -ENOSPC; - } - - /* We're about to use some buffers from the free list. */ - vq->vq.num_free -= out + in; - - head = vq->free_head; - for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) { - vq->vring.desc[i].flags = VRING_DESC_F_NEXT; - vq->vring.desc[i].addr = sg_phys(sg); - vq->vring.desc[i].len = sg->length; - prev = i; - sg++; - } - for (; in; i = vq->vring.desc[i].next, in--) { - vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; - vq->vring.desc[i].addr = sg_phys(sg); - vq->vring.desc[i].len = sg->length; - prev = i; - sg++; - } - /* Last one doesn't continue. */ - vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; - - /* Update free pointer */ - vq->free_head = i; - -add_head: - /* Set token. */ - vq->data[head] = data; - - /* Put entry in available array (but don't update avail->idx until they - * do sync). */ - avail = (vq->vring.avail->idx & (vq->vring.num-1)); - vq->vring.avail->ring[avail] = head; - - /* Descriptors and available array need to be set before we expose the - * new available array entries. */ - virtio_wmb(vq); - vq->vring.avail->idx++; - vq->num_added++; + int ret; - /* This is very unlikely, but theoretically possible. Kick - * just in case. */ - if (unlikely(vq->num_added == (1 << 16) - 1)) - virtqueue_kick(_vq); + ret = virtqueue_start_buf(vq, data, out + in, !!out + !!in, gfp); + if (ret < 0) + return ret; - pr_debug("Added buffer head %i to %p\n", head, vq); - END_USE(vq); + if (out) + virtqueue_add_sg(vq, sg, out, DMA_TO_DEVICE); + if (in) + virtqueue_add_sg(vq, sg + out, in, DMA_FROM_DEVICE); + virtqueue_end_buf(vq); return 0; } EXPORT_SYMBOL_GPL(virtqueue_add_buf); @@ -537,8 +401,7 @@ EXPORT_SYMBOL_GPL(virtqueue_start_buf); * @nents: the number of items to process in sgl * @dir: whether the sgl is read or written (DMA_TO_DEVICE/DMA_FROM_DEVICE only) * - * Note that, unlike virtqueue_add_buf, this function follows chained - * scatterlists, and stops before the @nents-th item if a scatterlist item + * This function will stop before the @nents-th item if a scatterlist item * has a marker. * * Caller must ensure we don't call this with other virtqueue operations -- 1.7.1