diff options
Diffstat (limited to 'drivers/iommu/dma-iommu.c')
| -rw-r--r-- | drivers/iommu/dma-iommu.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index e57724163835..4b1a88f514c9 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -660,7 +660,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, { struct iommu_dma_cookie *cookie = domain->iova_cookie; struct iova_domain *iovad = &cookie->iovad; - unsigned long shift, iova_len, iova = 0; + unsigned long shift, iova_len, iova; if (cookie->type == IOMMU_DMA_MSI_COOKIE) { cookie->msi_iova += size; @@ -675,15 +675,29 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, if (domain->geometry.force_aperture) dma_limit = min(dma_limit, (u64)domain->geometry.aperture_end); - /* Try to get PCI devices a SAC address */ - if (dma_limit > DMA_BIT_MASK(32) && !iommu_dma_forcedac && dev_is_pci(dev)) + /* + * Try to use all the 32-bit PCI addresses first. The original SAC vs. + * DAC reasoning loses relevance with PCIe, but enough hardware and + * firmware bugs are still lurking out there that it's safest not to + * venture into the 64-bit space until necessary. + * + * If your device goes wrong after seeing the notice then likely either + * its driver is not setting DMA masks accurately, the hardware has + * some inherent bug in handling >32-bit addresses, or not all the + * expected address bits are wired up between the device and the IOMMU. + */ + if (dma_limit > DMA_BIT_MASK(32) && dev->iommu->pci_32bit_workaround) { iova = alloc_iova_fast(iovad, iova_len, DMA_BIT_MASK(32) >> shift, false); + if (iova) + goto done; - if (!iova) - iova = alloc_iova_fast(iovad, iova_len, dma_limit >> shift, - true); + dev->iommu->pci_32bit_workaround = false; + dev_notice(dev, "Using %d-bit DMA addresses\n", bits_per(dma_limit)); + } + iova = alloc_iova_fast(iovad, iova_len, dma_limit >> shift, true); +done: return (dma_addr_t)iova << shift; } |