From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
sparclinux@vger.kernel.org, Joerg Roedel <jroedel@suse.de>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Sebastian Ott <sebott@linux.vnet.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Christoph Hellwig <hch@lst.de>,
benh@kernel.crashing.org, KVM <kvm@vger.kernel.org>,
dwmw2@infradead.org, Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-s390 <linux-s390@vger.kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v4 2/6] virtio_ring: Support DMA APIs
Date: Fri, 30 Oct 2015 13:01:16 +0100 [thread overview]
Message-ID: <20151030130116.52a87922.cornelia.huck@de.ibm.com> (raw)
In-Reply-To: <7c590bf685f5cbc3f01e42bdbc1dbe3ffd83420f.1446162273.git.luto@kernel.org>
On Thu, 29 Oct 2015 18:09:47 -0700
Andy Lutomirski <luto@kernel.org> wrote:
> virtio_ring currently sends the device (usually a hypervisor)
> physical addresses of its I/O buffers. This is okay when DMA
> addresses and physical addresses are the same thing, but this isn't
> always the case. For example, this never works on Xen guests, and
> it is likely to fail if a physical "virtio" device ever ends up
> behind an IOMMU or swiotlb.
>
> The immediate use case for me is to enable virtio on Xen guests.
> For that to work, we need vring to support DMA address translation
> as well as a corresponding change to virtio_pci or to another
> driver.
>
> With this patch, if enabled, virtfs survives kmemleak and
> CONFIG_DMA_API_DEBUG.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> drivers/virtio/Kconfig | 2 +-
> drivers/virtio/virtio_ring.c | 190 +++++++++++++++++++++++++++++++--------
> tools/virtio/linux/dma-mapping.h | 17 ++++
> 3 files changed, 172 insertions(+), 37 deletions(-)
> create mode 100644 tools/virtio/linux/dma-mapping.h
> static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
> {
> - unsigned int i;
> + unsigned int i, j;
> + u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
>
> /* Clear data ptr. */
> - vq->data[head] = NULL;
> + vq->desc_state[head].data = NULL;
>
> - /* Put back on free list: find end */
> + /* Put back on free list: unmap first-level descriptors and find end */
> i = head;
>
> - /* Free the indirect table */
> - if (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT))
> - kfree(phys_to_virt(virtio64_to_cpu(vq->vq.vdev, vq->vring.desc[i].addr)));
> -
> - while (vq->vring.desc[i].flags & cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT)) {
> + while (vq->vring.desc[i].flags & nextflag) {
> + vring_unmap_one(vq, &vq->vring.desc[i]);
> i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
> vq->vq.num_free++;
> }
>
> + vring_unmap_one(vq, &vq->vring.desc[i]);
> vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
> vq->free_head = head;
> +
> /* Plus final descriptor */
> vq->vq.num_free++;
> +
> + /* Free the indirect table, if any, now that it's unmapped. */
> + if (vq->desc_state[head].indir_desc) {
> + struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
> + u32 len = vq->vring.desc[head].len;
This one needs to be virtio32_to_cpu(...) as well.
> +
> + BUG_ON(!(vq->vring.desc[head].flags &
> + cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
> + BUG_ON(len == 0 || len % sizeof(struct vring_desc));
> +
> + for (j = 0; j < len / sizeof(struct vring_desc); j++)
> + vring_unmap_one(vq, &indir_desc[j]);
> +
> + kfree(vq->desc_state[head].indir_desc);
> + vq->desc_state[head].indir_desc = NULL;
> + }
> }
With that change on top of your current branch, I can boot (root on
virtio-blk, either virtio-1 or legacy virtio) on current qemu master
with kvm enabled on s390. Haven't tried anything further.
next prev parent reply other threads:[~2015-10-30 12:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 1:09 [PATCH v4 0/6] virtio core DMA API conversion Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 1/6] virtio-net: Stop doing DMA from the stack Andy Lutomirski
2015-10-30 13:55 ` Christian Borntraeger
2015-10-31 5:02 ` Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 2/6] virtio_ring: Support DMA APIs Andy Lutomirski
2015-10-30 12:01 ` Cornelia Huck [this message]
2015-10-30 12:05 ` Christian Borntraeger
2015-10-30 18:51 ` Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 3/6] virtio_pci: Use the DMA API Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 4/6] virtio: Add improved queue allocation API Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 5/6] virtio_mmio: Use the DMA API Andy Lutomirski
2015-10-30 1:09 ` [PATCH v4 6/6] virtio_pci: " Andy Lutomirski
2015-10-30 1:17 ` [PATCH v4 0/6] virtio core DMA API conversion Andy Lutomirski
2015-10-30 9:57 ` Christian Borntraeger
2015-11-09 12:15 ` Michael S. Tsirkin
2015-11-09 12:27 ` Paolo Bonzini
2015-11-09 22:58 ` Benjamin Herrenschmidt
2015-11-10 0:46 ` Andy Lutomirski
2015-11-10 2:04 ` Benjamin Herrenschmidt
2015-11-10 2:18 ` Andy Lutomirski
2015-11-10 5:26 ` Benjamin Herrenschmidt
2015-11-10 5:33 ` Andy Lutomirski
2015-11-10 5:28 ` Benjamin Herrenschmidt
2015-11-10 5:35 ` Andy Lutomirski
2015-11-10 10:37 ` Benjamin Herrenschmidt
2015-11-10 12:43 ` Michael S. Tsirkin
2015-11-10 19:37 ` Benjamin Herrenschmidt
2015-11-10 18:54 ` Andy Lutomirski
2015-11-10 22:27 ` Benjamin Herrenschmidt
2015-11-10 23:44 ` Andy Lutomirski
2015-11-11 0:44 ` Benjamin Herrenschmidt
2015-11-11 4:46 ` Andy Lutomirski
2015-11-11 5:08 ` Benjamin Herrenschmidt
2015-11-10 7:28 ` Jan Kiszka
2015-11-10 9:45 ` Knut Omang
2015-11-10 10:26 ` Benjamin Herrenschmidt
2015-11-10 10:27 ` Joerg Roedel
2015-11-10 19:36 ` Benjamin Herrenschmidt
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