From: Joerg Roedel <joro@8bytes.org>
To: "Michael S . Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
virtualization@lists.linux-foundation.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, jfehlig@suse.com,
jon.grimm@amd.com, brijesh.singh@amd.com, joro@8bytes.org,
jroedel@suse.de
Subject: [PATCH 4/5] virtio: Introduce virtio_max_dma_size()
Date: Tue, 29 Jan 2019 09:43:41 +0100 [thread overview]
Message-ID: <20190129084342.26030-5-joro@8bytes.org> (raw)
In-Reply-To: <20190129084342.26030-1-joro@8bytes.org>
From: Joerg Roedel <jroedel@suse.de>
This function returns the maximum segment size for a single
dma transaction of a virtio device. The possible limit comes
from the SWIOTLB implementation in the Linux kernel, that
has an upper limit of (currently) 256kb of contiguous
memory it can map. Other DMA-API implementations might also
have limits.
Use the new dma_max_mapping_size() function to determine the
maximum mapping size when DMA-API is in use for virtio.
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
drivers/virtio/virtio_ring.c | 10 ++++++++++
include/linux/virtio.h | 2 ++
2 files changed, 12 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index cd7e755484e3..9ca3fe6af9fa 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -266,6 +266,16 @@ static bool vring_use_dma_api(struct virtio_device *vdev)
return false;
}
+size_t virtio_max_dma_size(struct virtio_device *vdev)
+{
+ size_t max_segment_size = SIZE_MAX;
+
+ if (vring_use_dma_api(vdev))
+ max_segment_size = dma_max_mapping_size(&vdev->dev);
+
+ return max_segment_size;
+}
+
static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
{
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index fa1b5da2804e..673fe3ef3607 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -157,6 +157,8 @@ int virtio_device_freeze(struct virtio_device *dev);
int virtio_device_restore(struct virtio_device *dev);
#endif
+size_t virtio_max_dma_size(struct virtio_device *vdev);
+
#define virtio_device_for_each_vq(vdev, vq) \
list_for_each_entry(vq, &vdev->vqs, list)
--
2.17.1
next prev parent reply other threads:[~2019-01-29 8:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-29 8:43 [PATCH 0/5 v4] Fix virtio-blk issue with SWIOTLB Joerg Roedel
2019-01-29 8:43 ` [PATCH 1/5] swiotlb: Introduce swiotlb_max_mapping_size() Joerg Roedel
2019-01-29 17:12 ` Christoph Hellwig
2019-01-29 8:43 ` [PATCH 2/5] swiotlb: Add is_swiotlb_active() function Joerg Roedel
2019-01-29 17:12 ` Christoph Hellwig
2019-01-29 8:43 ` [PATCH 3/5] dma: Introduce dma_max_mapping_size() Joerg Roedel
2019-01-29 17:13 ` Christoph Hellwig
2019-01-30 15:09 ` Lendacky, Thomas
2019-01-29 8:43 ` Joerg Roedel [this message]
2019-01-29 17:13 ` [PATCH 4/5] virtio: Introduce virtio_max_dma_size() Christoph Hellwig
2019-01-30 15:10 ` Lendacky, Thomas
2019-01-30 15:49 ` Joerg Roedel
2019-01-29 8:43 ` [PATCH 5/5] virtio-blk: Consider virtio_max_dma_size() for maximum segment size Joerg Roedel
2019-01-29 17:13 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2019-01-31 16:33 [PATCH 0/5 v6] Fix virtio-blk issue with SWIOTLB Joerg Roedel
2019-01-31 16:34 ` [PATCH 4/5] virtio: Introduce virtio_max_dma_size() Joerg Roedel
2019-01-30 16:40 [PATCH 0/5 v5] Fix virtio-blk issue with SWIOTLB Joerg Roedel
2019-01-30 16:40 ` [PATCH 4/5] virtio: Introduce virtio_max_dma_size() Joerg Roedel
2019-01-23 16:30 [PATCH 0/5 v3] Fix virtio-blk issue with SWIOTLB Joerg Roedel
2019-01-23 16:30 ` [PATCH 4/5] virtio: Introduce virtio_max_dma_size() Joerg Roedel
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