Messages in this thread | | | Date | Tue, 19 Dec 2023 11:12:16 +0000 | Subject | Re: [PATCH V2] iommu: Don't reserve 0-length IOVA region | From | Robin Murphy <> |
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On 2023-12-05 6:56 am, Ashish Mhetre wrote: > When the bootloader/firmware doesn't setup the framebuffers, their > address and size are 0 in "iommu-addresses" property. If IOVA region is > reserved with 0 length, then it ends up corrupting the IOVA rbtree with > an entry which has pfn_hi < pfn_lo. > If we intend to use display driver in kernel without framebuffer then > it's causing the display IOMMU mappings to fail as entire valid IOVA > space is reserved when address and length are passed as 0. > An ideal solution would be firmware removing the "iommu-addresses" > property and corresponding "memory-region" if display is not present. > But the kernel should be able to handle this by checking for size of > IOVA region and skipping the IOVA reservation if size is 0. Also, add > a warning if firmware is requesting 0-length IOVA region reservation.
Acked-by: Robin Murphy <robin.murphy@arm.com>
> Fixes: a5bf3cfce8cb ("iommu: Implement of_iommu_get_resv_regions()") > Signed-off-by: Ashish Mhetre <amhetre@nvidia.com> > --- > drivers/iommu/of_iommu.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index 47302b637cc0..42cffb0ee5e2 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -264,6 +264,10 @@ void of_iommu_get_resv_regions(struct device *dev, struct list_head *list) > prot |= IOMMU_CACHE; > > maps = of_translate_dma_region(np, maps, &iova, &length); > + if (length == 0) { > + dev_warn(dev, "Cannot reserve IOVA region of 0 size\n"); > + continue; > + } > type = iommu_resv_region_get_type(dev, &phys, iova, length); > > region = iommu_alloc_resv_region(iova, length, prot, type,
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