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7d40c3953e
With Linux v6.1, if CONFIG_PCI_P2PDMA is enabled, then mapping the
syncpt shim causes a kernel paging request fault. The fault occurs when
dma_map_sg_attrs() is called in by nvhost_syncpt_unit_interface_init(),
which is attempting to map the syncpt shim MMIO space.
The function dma_map_sg_attrs() calls iomm_dma_map_sg() and since
upstream Linux commit 30280eee2db1 ("iommu/dma: support PCI P2PDMA pages
in dma-iommu map_sg") was added this now calls is_pci_p2pdma_page(). The
function is_pci_p2pdma_page() requires that there is a 'struct page'
associated with the sg, but this is not the case and so deferencing the
'struct page' pointer returned by sg_page() results in a paging fault.
Using dma_map_sg_attrs() to map MMIO that is not associated with valid
page structures is not guaranteed to work. Therefore, fix this by using
dma_map_resource() to map the syncpt shim instead.
Bug 3871422
Change-Id: I2b08a3b78be0850bff44e62bfc93c8d095eb82a2
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2818417
(cherry picked from commit 97f1282f2959c208effebf93cc5061d6e7fa6c55)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2819086
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>