Am 19.11.2020 um 20:18 schrieb Shay Agroskin:
>
> Heiner Kallweit <hkallwe...@gmail.com> writes:
>
>> 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 <mike...@amazon.com>
>>>> Signed-off-by: Arthur Kiyanovski <akiy...@amazon.com>
>>>> Signed-off-by: Shay Agroskin <shay...@amazon.com>
>>>> ---
>>>> 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));
>
> Thank you for reviewing these patches. We will switch to using dma_set_...()
> instead
>
>>>
>>
>> However instead of dev_err(&pdev->dev, ..) you could use pci_err(pdev, ..).
>
> I see that pci_err evaluates to dev_err. While I see how using pci_* log
> function helps code readability, I prefer using
> dev_err here to keep the code consistent with the rest of the driver. We'll
> discuss changing all log functions in future patches to net-next if that's
> okay.
>
The comment was just meant to make you aware of pci_err(), there's no need
to switch to it.
