From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: iommu@lists.linux-foundation.org,
virtualization@lists.linux-foundation.org
Cc: robin.murphy@arm.com, Bharat Bhushan <bbhushan2@marvell.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: [PATCH] iommu/virtio: Reject IOMMU page granule larger than PAGE_SIZE
Date: Wed, 18 Mar 2020 12:40:48 +0100 [thread overview]
Message-ID: <20200318114047.1518048-1-jean-philippe@linaro.org> (raw)
We don't currently support IOMMUs with a page granule larger than the
system page size. The IOVA allocator has a BUG_ON() in this case, and
VFIO has a WARN_ON().
It might be possible to remove these obstacles if necessary. If the host
uses 64kB pages and the guest uses 4kB, then a device driver calling
alloc_page() followed by dma_map_page() will create a 64kB mapping for a
4kB physical page, allowing the endpoint to access the neighbouring 60kB
of memory. This problem could be worked around with bounce buffers.
For the moment, rather than triggering the IOVA BUG_ON() on mismatched
page sizes, abort the virtio-iommu probe with an error message.
Reported-by: Bharat Bhushan <bbhushan2@marvell.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
drivers/iommu/virtio-iommu.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 6d4e3c2a2ddb..80d5d8f621ab 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -998,6 +998,7 @@ static int viommu_probe(struct virtio_device *vdev)
struct device *parent_dev = vdev->dev.parent;
struct viommu_dev *viommu = NULL;
struct device *dev = &vdev->dev;
+ unsigned long viommu_page_size;
u64 input_start = 0;
u64 input_end = -1UL;
int ret;
@@ -1028,6 +1029,14 @@ static int viommu_probe(struct virtio_device *vdev)
goto err_free_vqs;
}
+ viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap);
+ if (viommu_page_size > PAGE_SIZE) {
+ dev_err(dev, "granule 0x%lx larger than system page size 0x%lx\n",
+ viommu_page_size, PAGE_SIZE);
+ ret = -EINVAL;
+ goto err_free_vqs;
+ }
+
viommu->map_flags = VIRTIO_IOMMU_MAP_F_READ | VIRTIO_IOMMU_MAP_F_WRITE;
viommu->last_domain = ~0U;
--
2.25.1
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next reply other threads:[~2020-03-18 11:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 11:40 Jean-Philippe Brucker [this message]
2020-03-18 12:00 ` [PATCH] iommu/virtio: Reject IOMMU page granule larger than PAGE_SIZE Robin Murphy
2020-03-18 16:14 ` Auger Eric
2020-03-18 17:06 ` Jean-Philippe Brucker
2020-03-18 17:13 ` Robin Murphy
2020-03-18 17:47 ` Jean-Philippe Brucker
2020-03-19 18:54 ` Alex Williamson
2020-03-25 21:05 ` Auger Eric
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