Re: [PATCH 3/3] virtio-blk: Consider dma_max_mapping_size() for maximum segment size
On Wed, Jan 16, 2019 at 09:05:40AM -0500, Michael S. Tsirkin wrote: > On Tue, Jan 15, 2019 at 02:22:57PM +0100, Joerg Roedel wrote: > > + max_size = dma_max_mapping_size(&vdev->dev); > > + > > > Should this be limited to ACCESS_PLATFORM? > > I see no reason to limit this without as guest can > access any memory. Actually, yes. This should be inside a use_dma_api check. I had it in v1, but it went away without the vring layer for propagating the limit. I'll add that again. Thanks, Joerg ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 3/3] virtio-blk: Consider dma_max_mapping_size() for maximum segment size
On Tue, Jan 15, 2019 at 02:22:57PM +0100, Joerg Roedel wrote: > From: Joerg Roedel > > Segments can't be larger than the maximum DMA mapping size > supported on the platform. Take that into account when > setting the maximum segment size for a block device. > > Signed-off-by: Joerg Roedel > --- > drivers/block/virtio_blk.c | 10 ++ > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index b16a887bbd02..6193962a7fec 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -723,7 +723,7 @@ static int virtblk_probe(struct virtio_device *vdev) > struct request_queue *q; > int err, index; > > - u32 v, blk_size, sg_elems, opt_io_size; > + u32 v, blk_size, max_size, sg_elems, opt_io_size; > u16 min_io_size; > u8 physical_block_exp, alignment_offset; > > @@ -826,14 +826,16 @@ static int virtblk_probe(struct virtio_device *vdev) > /* No real sector limit. */ > blk_queue_max_hw_sectors(q, -1U); > > + max_size = dma_max_mapping_size(&vdev->dev); > + Should this be limited to ACCESS_PLATFORM? I see no reason to limit this without as guest can access any memory. I'd like a bit of time to consider this point. > /* Host can optionally specify maximum segment size and number of >* segments. */ > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX, > struct virtio_blk_config, size_max, &v); > if (!err) > - blk_queue_max_segment_size(q, v); > - else > - blk_queue_max_segment_size(q, -1U); > + max_size = min(max_size, v); > + > + blk_queue_max_segment_size(q, max_size); > > /* Host can optionally specify the block size of the device */ > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE, > -- > 2.17.1 ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH 3/3] virtio-blk: Consider dma_max_mapping_size() for maximum segment size
From: Joerg Roedel Segments can't be larger than the maximum DMA mapping size supported on the platform. Take that into account when setting the maximum segment size for a block device. Signed-off-by: Joerg Roedel --- drivers/block/virtio_blk.c | 10 ++ 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index b16a887bbd02..6193962a7fec 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -723,7 +723,7 @@ static int virtblk_probe(struct virtio_device *vdev) struct request_queue *q; int err, index; - u32 v, blk_size, sg_elems, opt_io_size; + u32 v, blk_size, max_size, sg_elems, opt_io_size; u16 min_io_size; u8 physical_block_exp, alignment_offset; @@ -826,14 +826,16 @@ static int virtblk_probe(struct virtio_device *vdev) /* No real sector limit. */ blk_queue_max_hw_sectors(q, -1U); + max_size = dma_max_mapping_size(&vdev->dev); + /* Host can optionally specify maximum segment size and number of * segments. */ err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX, struct virtio_blk_config, size_max, &v); if (!err) - blk_queue_max_segment_size(q, v); - else - blk_queue_max_segment_size(q, -1U); + max_size = min(max_size, v); + + blk_queue_max_segment_size(q, max_size); /* Host can optionally specify the block size of the device */ err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE, -- 2.17.1 ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
