This reverts commit 7bd6680b47fa4cd53ee1047693c09825e212a6f5.
When booting a sc7180-trogdor based device on mainline, I see errors
that look like this:
qcom_scm firmware:scm: Assign memory protection call failed -22
qcom_rmtfs_mem 94600000.memory: assign memory failed
qcom_rmtfs_mem: probe of 94600000.memory failed with error -22
The device still boots OK, but WiFi doesn't work.
The failure only seems to happen when
CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y. When I don't have that set then
everything is peachy. Presumably something about the extra
initialization disagrees with the change to drop cache invalidation.
Fixes: 7bd6680b47fa ("Revert "Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()""")
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
arch/arm64/mm/dma-mapping.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 3cb101e8cb29..5240f6acad64 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -36,7 +36,22 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
{
unsigned long start = (unsigned long)page_address(page);
- dcache_clean_poc(start, start + size);
+ /*
+ * The architecture only requires a clean to the PoC here in order to
+ * meet the requirements of the DMA API. However, some vendors (i.e.
+ * Qualcomm) abuse the DMA API for transferring buffers from the
+ * non-secure to the secure world, resetting the system if a non-secure
+ * access shows up after the buffer has been transferred:
+ *
+ * https://lore.kernel.org/r/20221114110329.68413-1-manivannan.sadhasivam@xxxxxxxxxx
+ *
+ * Using clean+invalidate appears to make this issue less likely, but
+ * the drivers themselves still need fixing as the CPU could issue a
+ * speculative read from the buffer via the linear mapping irrespective
+ * of the cache maintenance we use. Once the drivers are fixed, we can
+ * relax this to a clean operation.
+ */
+ dcache_clean_inval_poc(start, start + size);
}
#ifdef CONFIG_IOMMU_DMA
--
2.41.0.162.gfafddb0af9-goog
