From: Alexey Kardashevskiy aik@ozlabs.ru
commit 437ef802e0adc9f162a95213a3488e8646e5fc03 upstream.
There are 2 problems with it: 1. "<" vs expected "<<" 2. the shift number is an IOMMU page number mask, not an address mask as the IOMMU page shift is missing.
This did not hit us before f1565c24b596 ("powerpc: use the generic dma_ops_bypass mode") because we had additional code to handle bypass mask so this chunk (almost?) never executed.However there were reports that aacraid does not work with "iommu=nobypass".
After f1565c24b596, aacraid (and probably others which call dma_get_required_mask() before setting the mask) was unable to enable 64bit DMA and fall back to using IOMMU which was known not to work, one of the problems is double free of an IOMMU page.
This fixes DMA for aacraid, both with and without "iommu=nobypass" in the kernel command line. Verified with "stress-ng -d 4".
Fixes: 6a5c7be5e484 ("powerpc: Override dma_get_required_mask by platform hook and ops") Cc: stable@vger.kernel.org # v3.2+ Signed-off-by: Alexey Kardashevskiy aik@ozlabs.ru Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200908015106.79661-1-aik@ozlabs.ru Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/kernel/dma-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/dma-iommu.c +++ b/arch/powerpc/kernel/dma-iommu.c @@ -100,7 +100,8 @@ static u64 dma_iommu_get_required_mask(s if (!tbl) return 0;
- mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1); + mask = 1ULL << (fls_long(tbl->it_offset + tbl->it_size) + + tbl->it_page_shift - 1); mask += mask - 1;
return mask;