From 3909213cfd9224cb1827d557fb6eb5ebdb8ddcbe Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 14 Jan 2015 18:50:55 +0200 Subject: [PATCH] virtio_pci_modern: reduce number of mappings We don't know the # of VQs that drivers are going to use so it's hard to predict how much memory we'll need to map. However, the relevant capability does give us an upper limit. If that's below a page, we can reduce the number of required mappings by mapping it all once ahead of the time. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell --- drivers/virtio/virtio_pci_common.h | 3 ++ drivers/virtio/virtio_pci_modern.c | 57 +++++++++++++++++++++++++----- 2 files changed, 52 insertions(+), 8 deletions(-) diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h index 610c43f19230..d39180512761 100644 --- a/drivers/virtio/virtio_pci_common.h +++ b/drivers/virtio/virtio_pci_common.h @@ -62,8 +62,11 @@ struct virtio_pci_device { struct virtio_pci_common_cfg __iomem *common; /* Device-specific data (non-legacy mode) */ void __iomem *device; + /* Base of vq notifications (non-legacy mode). */ + void __iomem *notify_base; /* So we can sanity-check accesses. */ + size_t notify_len; size_t device_len; /* Capability for when we need to map notifications per-vq. */ diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c index b2e707ad81cf..0e54cc88fdf5 100644 --- a/drivers/virtio/virtio_pci_modern.c +++ b/drivers/virtio/virtio_pci_modern.c @@ -330,10 +330,26 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, iowrite64_twopart(virt_to_phys(virtqueue_get_used(vq)), &cfg->queue_used_lo, &cfg->queue_used_hi); - vq->priv = (void __force *)map_capability(vp_dev->pci_dev, - vp_dev->notify_map_cap, 2, 2, - off * vp_dev->notify_offset_multiplier, 2, - NULL); + if (vp_dev->notify_base) { + /* offset should not wrap */ + if ((u64)off * vp_dev->notify_offset_multiplier + 2 + > vp_dev->notify_len) { + dev_warn(&vp_dev->pci_dev->dev, + "bad notification offset %u (x %u) " + "for queue %u > %zd", + off, vp_dev->notify_offset_multiplier, + index, vp_dev->notify_len); + err = -EINVAL; + goto err_map_notify; + } + vq->priv = (void __force *)vp_dev->notify_base + + off * vp_dev->notify_offset_multiplier; + } else { + vq->priv = (void __force *)map_capability(vp_dev->pci_dev, + vp_dev->notify_map_cap, 2, 2, + off * vp_dev->notify_offset_multiplier, 2, + NULL); + } if (!vq->priv) { err = -ENOMEM; @@ -352,7 +368,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, return vq; err_assign_vector: - pci_iounmap(vp_dev->pci_dev, (void __iomem __force *)vq->priv); + if (!vp_dev->notify_base) + pci_iounmap(vp_dev->pci_dev, (void __iomem __force *)vq->priv); err_map_notify: vring_del_virtqueue(vq); err_new_queue: @@ -397,7 +414,8 @@ static void del_vq(struct virtio_pci_vq_info *info) ioread16(&vp_dev->common->queue_msix_vector); } - pci_iounmap(vp_dev->pci_dev, (void __force __iomem *)vq->priv); + if (!vp_dev->notify_base) + pci_iounmap(vp_dev->pci_dev, (void __force __iomem *)vq->priv); vring_del_virtqueue(vq); @@ -533,6 +551,7 @@ int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev) struct pci_dev *pci_dev = vp_dev->pci_dev; int err, common, isr, notify, device; u32 notify_length; + u32 notify_offset; check_offsets(); @@ -599,13 +618,30 @@ int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev) notify + offsetof(struct virtio_pci_notify_cap, notify_off_multiplier), &vp_dev->notify_offset_multiplier); - /* Read notify length from config space. */ + /* Read notify length and offset from config space. */ pci_read_config_dword(pci_dev, notify + offsetof(struct virtio_pci_notify_cap, cap.length), ¬ify_length); - vp_dev->notify_map_cap = notify; + pci_read_config_dword(pci_dev, + notify + offsetof(struct virtio_pci_notify_cap, + cap.length), + ¬ify_offset); + + /* We don't know how many VQs we'll map, ahead of the time. + * If notify length is small, map it all now. + * Otherwise, map each VQ individually later. + */ + if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) { + vp_dev->notify_base = map_capability(pci_dev, notify, 2, 2, + 0, notify_length, + &vp_dev->notify_len); + if (!vp_dev->notify_base) + goto err_map_notify; + } else { + vp_dev->notify_map_cap = notify; + } /* Again, we don't know how much we should map, but PAGE_SIZE * is more than enough for all existing devices. @@ -627,6 +663,9 @@ int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev) return 0; err_map_device: + if (vp_dev->notify_base) + pci_iounmap(pci_dev, vp_dev->notify_base); +err_map_notify: pci_iounmap(pci_dev, vp_dev->isr); err_map_isr: pci_iounmap(pci_dev, vp_dev->common); @@ -640,6 +679,8 @@ void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev) if (vp_dev->device) pci_iounmap(pci_dev, vp_dev->device); + if (vp_dev->notify_base) + pci_iounmap(pci_dev, vp_dev->notify_base); pci_iounmap(pci_dev, vp_dev->isr); pci_iounmap(pci_dev, vp_dev->common); } -- 2.30.2