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vdpa_sim: hold iommu_lock across dma_unmap passthrough transition

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vdpasim_dma_map() updates the IOTLB and the passthrough (iommu_pt)
state under iommu_lock.  vdpasim_dma_unmap() clears iommu_pt and
resets the IOTLB before taking iommu_lock, then deletes the mapping
while holding the lock.

A concurrent dma_map(), dma_unmap(), or reset path that also touches
the same address space can therefore observe or modify the IOTLB and
iommu_pt state without consistent locking.

Perform the passthrough transition and range deletion under the same
iommu_lock scope, matching dma_map().

Tested-on: openEuler VM (6.16.8, /usr/src/linux-6.16.8)
Tested-by: Xiong Weimin <xiongweimin@kylinos.cn>

Signed-off-by: Xiong Weimin <xiongweimin@kylinos.cn>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260626020545.607600-3-15927021679@163.com>
This commit is contained in:
Xiong Weimin 2026-06-26 10:05:45 +08:00 committed by Michael S. Tsirkin
parent 135f0abe31
commit 7b411448c6
1 changed files with 1 additions and 2 deletions
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3
drivers/vdpa/vdpa_sim/vdpa_sim.c
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@ -733,12 +733,11 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
if (asid >= vdpasim->dev_attr.nas)
return -EINVAL;
spin_lock(&vdpasim->iommu_lock);
if (vdpasim->iommu_pt[asid]) {
vhost_iotlb_reset(&vdpasim->iommu[asid]);
vdpasim->iommu_pt[asid] = false;
}
spin_lock(&vdpasim->iommu_lock);
vhost_iotlb_del_range(&vdpasim->iommu[asid], iova, iova + size - 1);
spin_unlock(&vdpasim->iommu_lock);