From b0a2fe148a70dc805f1e11702a08a7065418a8dd Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 29 Mar 2023 22:25:00 +0800 Subject: [PATCH] virtio: Use bounce buffers when VIRTIO_F_IOMMU_PLATFORM is set Devices advertising the VIRTIO_F_IOMMU_PLATFORM feature require platform-specific handling to configure their DMA transactions. When handling virtio descriptors for such a device, use bounce buffers to ensure that the underlying buffers are always aligned to and padded to PAGE_SIZE in preparation for platform specific handling at page granularity. Signed-off-by: Will Deacon [ Paul: pick from the Android tree. Rebase to the upstream ] Signed-off-by: Ying-Chun Liu (PaulLiu) Cc: Bin Meng Link: https://android.googlesource.com/platform/external/u-boot/+/1eff171e613ee67dca71dbe97be7282e2db17011 Reviewed-by: Simon Glass --- drivers/virtio/virtio_ring.c | 48 +++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index de75786ca7..c9adcce5c0 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -28,14 +28,51 @@ static void virtio_free_pages(struct udevice *vdev, void *ptr, u32 npages) free(ptr); } +static int __bb_force_page_align(struct bounce_buffer *state) +{ + const ulong align_mask = PAGE_SIZE - 1; + + if ((ulong)state->user_buffer & align_mask) + return 0; + + if (state->len != state->len_aligned) + return 0; + + return 1; +} + static unsigned int virtqueue_attach_desc(struct virtqueue *vq, unsigned int i, struct virtio_sg *sg, u16 flags) { struct vring_desc_shadow *desc_shadow = &vq->vring_desc_shadow[i]; struct vring_desc *desc = &vq->vring.desc[i]; + void *addr; + + if (IS_ENABLED(CONFIG_BOUNCE_BUFFER) && vq->vring.bouncebufs) { + struct bounce_buffer *bb = &vq->vring.bouncebufs[i]; + unsigned int bbflags; + int ret; + + if (flags & VRING_DESC_F_WRITE) + bbflags = GEN_BB_WRITE; + else + bbflags = GEN_BB_READ; + + ret = bounce_buffer_start_extalign(bb, sg->addr, sg->length, + bbflags, PAGE_SIZE, + __bb_force_page_align); + if (ret) { + debug("%s: failed to allocate bounce buffer (length 0x%zx)\n", + vq->vdev->name, sg->length); + } + + addr = bb->bounce_buffer; + } else { + addr = sg->addr; + } /* Update the shadow descriptor. */ - desc_shadow->addr = (u64)(uintptr_t)sg->addr; + desc_shadow->addr = (u64)(uintptr_t)addr; desc_shadow->len = sg->length; desc_shadow->flags = flags; @@ -50,6 +87,15 @@ static unsigned int virtqueue_attach_desc(struct virtqueue *vq, unsigned int i, static void virtqueue_detach_desc(struct virtqueue *vq, unsigned int idx) { + struct vring_desc *desc = &vq->vring.desc[idx]; + struct bounce_buffer *bb; + + if (!IS_ENABLED(CONFIG_BOUNCE_BUFFER) || !vq->vring.bouncebufs) + return; + + bb = &vq->vring.bouncebufs[idx]; + bounce_buffer_stop(bb); + desc->addr = cpu_to_virtio64(vq->vdev, (u64)(uintptr_t)bb->user_buffer); } int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[], -- 2.39.5