This patch sets the coherent DMA mask to 64-bit after the be2net driver has been acknowledged that the system is 64-bit DMA capable. The coherent DMA mask is examined by the Intel IOMMU driver to determine whether to allow pass through context mapping for all devices. With this patch, the be2net driver combined with be2net compatible hardware provides comparable performance to the case where vt-d is disabled. The main use case for this change is to decrease the time necessary to copy virtual machine memory during KVM live migration instantiations.
This patch was tested on a system that enables the IOMMU in non-coherent mode. Two DMA remapper issues were encountered and both are in the Intel IOMMU driver with the following patches submitted upstream but not yet commited. Patch 1 - DMAR:[fault reason 02] Present bit in context entry is clear https://lkml.org/lkml/2012/6/15/20 Patch 2 - DMAR:[fault reason 02] Present bit in context entry is clear https://lkml.org/lkml/2011/11/11/279 Signed-off-by: Craig Hada <[email protected]> --- drivers/net/ethernet/emulex/benet/be_main.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c index 78b8aa8..57bbea4 100644 --- a/drivers/net/ethernet/emulex/benet/be_main.c +++ b/drivers/net/ethernet/emulex/benet/be_main.c @@ -3835,6 +3835,12 @@ static int __devinit be_probe(struct pci_dev *pdev, status = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64)); if (!status) { + status = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64)); + if (status < 0) { + dev_err(&pdev->dev, + "dma_set_coherent_mask failed, aborting\n"); + goto free_netdev; + } netdev->features |= NETIF_F_HIGHDMA; } else { status = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32)); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
