Messages in this thread | | | Subject | Re: [PATCH v3 5/8] iommu/vt-d: Implement def_domain_type iommu ops entry | From | Lu Baolu <> | Date | Tue, 30 Apr 2019 10:11:42 +0800 |
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Hi Christoph,
On 4/30/19 4:03 AM, Christoph Hellwig wrote: >> @@ -3631,35 +3607,30 @@ static int iommu_no_mapping(struct device *dev) >> if (iommu_dummy(dev)) >> return 1; >> >> - if (!iommu_identity_mapping) >> - return 0; >> - > > FYI, iommu_no_mapping has been refactored in for-next: > > https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/commit/?h=x86/vt-d&id=48b2c937ea37a3bece0094b46450ed5267525289
Oh, yes! Thanks for letting me know this. Will rebase the code.
> >> found = identity_mapping(dev); >> if (found) { >> + /* >> + * If the device's dma_mask is less than the system's memory >> + * size then this is not a candidate for identity mapping. >> + */ >> + u64 dma_mask = *dev->dma_mask; >> + >> + if (dev->coherent_dma_mask && >> + dev->coherent_dma_mask < dma_mask) >> + dma_mask = dev->coherent_dma_mask; >> + >> + if (dma_mask < dma_get_required_mask(dev)) { > > I know this is mostly existing code moved around, but it really needs > some fixing. For one dma_get_required_mask is supposed to return the > required to not bounce mask for the given device. E.g. for a device > behind an iommu it should always just return 32-bit. If you really > want to check vs system memory please call dma_direct_get_required_mask > without the dma_ops indirection. > > Second I don't even think we need to check the coherent_dma_mask, > dma_direct is pretty good at always finding memory even without > an iommu. > > Third this doesn't take take the bus_dma_mask into account. > > This probably should just be: > > if (min(*dev->dma_mask, dev->bus_dma_mask) < > dma_direct_get_required_mask(dev)) {
Agreed and will add this in the next version.
Best regards, Lu Baolu
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