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SubjectRe: [PATCH] vfio powerpc: implemented IOMMU driver for VFIO
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On Wed, 2012-12-12 at 17:59 +1100, Alexey Kardashevskiy wrote:
> On 08/12/12 04:01, Alex Williamson wrote:
> >> + case VFIO_IOMMU_MAP_DMA: {
> >> + vfio_iommu_spapr_tce_dma_map param;
> >> + struct iommu_table *tbl = container->tbl;
> >> + enum dma_data_direction direction;
> >> + unsigned long locked, lock_limit;
> >> +
> >> + if (WARN_ON(!tbl))
> >> + return -ENXIO;
> >> +
> >> + minsz = offsetofend(vfio_iommu_spapr_tce_dma_map, size);
> >> +
> >> + if (copy_from_user(&param, (void __user *)arg, minsz))
> >> + return -EFAULT;
> >> +
> >> + if (param.argsz < minsz)
> >> + return -EINVAL;
> >> +
> >> + if ((param.flags & VFIO_DMA_MAP_FLAG_READ) &&
> >> + (param.flags & VFIO_DMA_MAP_FLAG_WRITE))
> >> + direction = DMA_BIDIRECTIONAL;
> >> + else if (param.flags & VFIO_DMA_MAP_FLAG_READ)
> >> + direction = DMA_TO_DEVICE;
> >> + else if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
> >> + direction = DMA_FROM_DEVICE;
> >> + else
> >> + return -EINVAL;
> >
> > flags needs to be sanitized too. Return EINVAL if any unknown bit is
> > set or else sloppy users may make it very difficult to make use of those
> > flag bits later.
>
>
> It already returns -EINVAL on any bit set except READ/WRITE, no?

No. I could pass flags ~0 through there to get a read/write mapping and
cause you problems if you later want to define another bit. Thanks,

Alex



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