On Tue, Jul 11, 2017 at 02:34:47PM -0700, Tushar Dave wrote:
> 64bit DMA only supported on sun4v equipped with ATU IOMMU HW.
> 'Commit b02c2b0bfd7ae ("sparc: remove arch specific dma_supported
> implementations")' introduced a code that incorrectly allow
> dma_supported() to succeed for 64bit dma mask even if system doesn't
> have ATU IOMMU. This results into panic.
>
> Fix it.
>
> Reported-by: Meelis Roos <mroos@xxxxxxxx>
> Signed-off-by: Tushar Dave <tushar.n.dave@xxxxxxxxxx>
> ---
> arch/sparc/kernel/pci_sun4v.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/sparc/kernel/pci_sun4v.c b/arch/sparc/kernel/pci_sun4v.c
> index 24f21c7..f10e2f7 100644
> --- a/arch/sparc/kernel/pci_sun4v.c
> +++ b/arch/sparc/kernel/pci_sun4v.c
> @@ -673,12 +673,14 @@ static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist,
> static int dma_4v_supported(struct device *dev, u64 device_mask)
> {
> struct iommu *iommu = dev->archdata.iommu;
> - u64 dma_addr_mask;
> + u64 dma_addr_mask = iommu->dma_addr_mask;
>
> - if (device_mask > DMA_BIT_MASK(32) && iommu->atu)
> - dma_addr_mask = iommu->atu->dma_addr_mask;
> - else
> - dma_addr_mask = iommu->dma_addr_mask;
> + if (device_mask > DMA_BIT_MASK(32)) {
> + if (iommu->atu)
> + dma_addr_mask = iommu->atu->dma_addr_mask;
> + else
> + return 0;
> + }
This would be more readable as:
if (device_mask > DMA_BIT_MASK(32)) {
if (!iommu->atu)
return 0;
dma_addr_mask = iommu->atu->dma_addr_mask;
}
But except for that it looks fine to me:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
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