Am 18.11.2020 um 23:35 schrieb Heiner Kallweit:
> Am 18.11.2020 um 22:59 schrieb Shay Agroskin:
>> The ENA driver uses the readless mechanism, which uses DMA, to find
>> out what the DMA mask is supposed to be.
>>
>> If DMA is used without setting the dma_mask first, it causes the
>> Intel IOMMU driver to think that ENA is a 32-bit device and therefore
>> disables IOMMU passthrough permanently.
>>
>> This patch sets the dma_mask to be ENA_MAX_PHYS_ADDR_SIZE_BITS=48
>> before readless initialization in
>> ena_device_init()->ena_com_mmio_reg_read_request_init(),
>> which is large enough to workaround the intel_iommu issue.
>>
>> DMA mask is set again to the correct value after it's received from the
>> device after readless is initialized.
>>
>> Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network
>> Adapters (ENA)")
>> Signed-off-by: Mike Cui <[email protected]>
>> Signed-off-by: Arthur Kiyanovski <[email protected]>
>> Signed-off-by: Shay Agroskin <[email protected]>
>> ---
>> drivers/net/ethernet/amazon/ena/ena_netdev.c | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> b/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> index 574c2b5ba21e..854a22e692bf 100644
>> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
>> @@ -4146,6 +4146,19 @@ static int ena_probe(struct pci_dev *pdev, const
>> struct pci_device_id *ent)
>> return rc;
>> }
>>
>> + rc = pci_set_dma_mask(pdev, DMA_BIT_MASK(ENA_MAX_PHYS_ADDR_SIZE_BITS));
>> + if (rc) {
>> + dev_err(&pdev->dev, "pci_set_dma_mask failed %d\n", rc);
>> + goto err_disable_device;
>> + }
>> +
>> + rc = pci_set_consistent_dma_mask(pdev,
>> DMA_BIT_MASK(ENA_MAX_PHYS_ADDR_SIZE_BITS));
>> + if (rc) {
>> + dev_err(&pdev->dev, "err_pci_set_consistent_dma_mask failed
>> %d\n",
>> + rc);
>> + goto err_disable_device;
>> + }
>> +
>> pci_set_master(pdev);
>>
>> ena_dev = vzalloc(sizeof(*ena_dev));
>>
>
> The old pci_ dma wrappers are being phased out and shouldn't be used in
> new code. See e.g. e059c6f340f6 ("tulip: switch from 'pci_' to 'dma_' API").
> So better use:
> dma_set_mask_and_coherent(&pdev->dev,
> DMA_BIT_MASK(ENA_MAX_PHYS_ADDR_SIZE_BITS));
>
However instead of dev_err(&pdev->dev, ..) you could use pci_err(pdev, ..).
