[PATCH V1 net 2/4] net: ena: set initial DMA width to avoid intel iommu issue

[Shay Agroskin <shayagr@amazon.com>]

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@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: Shay Agroskin <shayagr@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));
-- 
2.17.1