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Date: Thu, 19 Nov 2020 20:36:31 +0100 From: Heiner Kallweit <hkallweit1@...il.com> To: Shay Agroskin <shayagr@...zon.com> Cc: kuba@...nel.org, netdev@...r.kernel.org, dwmw@...zon.com, zorik@...zon.com, matua@...zon.com, saeedb@...zon.com, msw@...zon.com, aliguori@...zon.com, nafea@...zon.com, gtzalik@...zon.com, netanel@...zon.com, alisaidi@...zon.com, benh@...zon.com, akiyano@...zon.com, sameehj@...zon.com, ndagan@...zon.com, Mike Cui <mikecui@...zon.com> Subject: Re: [PATCH V1 net 2/4] net: ena: set initial DMA width to avoid intel iommu issue Am 19.11.2020 um 20:18 schrieb Shay Agroskin: > > Heiner Kallweit <hkallweit1@...il.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 <mikecui@...zon.com> >>>> Signed-off-by: Arthur Kiyanovski <akiyano@...zon.com> >>>> Signed-off-by: Shay Agroskin <shayagr@...zon.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.
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