On Mon, Oct 26, 2015 at 12:07:17PM -0400, Konrad Rzeszutek Wilk wrote: > On Mon, Aug 31, 2015 at 06:13:03PM -0400, j.gli...@gmail.com wrote: > > From: Jérôme Glisse <jgli...@redhat.com> > > > > Fix amd_iommu_detect() to return positive value on success, like > > intended, and not zero. This will not change anything in the end > > as AMD IOMMU disable swiotlb and properly associate itself with > > Not sure how it disables SWIOTLB? The AMD Vi does not seem to > change 'swiotlb'. While 'gart_iommu_init' does. Did you mean > the AMD GART code?
So this is convoluted and painfull, each i look back at that it takes me time to figure out of thing happen. Basicly amd_iommu_init_dma_ops() will replace dma_ops to no_mmu unless passthrough, and when the AMD iommu associate itself with each device it will set the archdata.dma_ops again this unbind the default of swiotlb that is initialize before hw IOMMU. > > > devices even if detect() doesn't return a positive value. > > Returning positive will mean that the pci_iommu_alloc will stop > processing _all_ other IOMMUs. > > While returning 0 will let it detect the other IOMMUs. No see the IOMMU_FINISH_IF_DETECTED flags in pci_iommu_alloc(). Which is not set for AMD hence my patch should not change anything it (AFAICT and from testing but i do not have all AMD hw the ever existed). So i am just making the detect function do what the API doc says it should do. See line 72 to 80 of : arch/x86/include/asm/iommu_table.h > > Granted on an AMD machine there can be two 'IOMMU's - the GART > and the AMD Vi. The detection is always to call gart_iommu_hole_init > first, then amd_iommu_detect. > > I presume if there was one more type on AMD we would run into trouble. No because of IOMMU_FINISH_IF_DETECTED flag. Hope this clarify thing this spagethi mix :) Cheers, Jérôme -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
