[PATCH net v3] net/mlx5: fix calling mlx5_cmd_init() before DMA mask is set

[Niklas Schnelle]

Since commit 06cd555f73ca ("net/mlx5: split mlx5_cmd_init() to probe and
reload routines") mlx5_cmd_init() is called in mlx5_mdev_init() which is
called in probe_one() before mlx5_pci_init(). This is a problem because
mlx5_pci_init() is where the DMA and coherent mask is set but
mlx5_cmd_init() already does a dma_alloc_coherent(). Thus a DMA
allocation is done during probe before the correct mask is set. This
causes probe to fail initialization of the cmdif SW structs on s390x
after that is converted to the common dma-iommu code. This is because on
s390x DMA addresses below 4 GiB are reserved on current machines and
unlike the old s390x specific DMA API implementation common code
enforces DMA masks.

Fix this by moving set_dma_caps() out of mlx5_pci_init() and into
probe_one() before mlx5_mdev_init(). To match the overall naming scheme
rename it to mlx5_dma_init().

Link: https://lore.kernel.org/linux-iommu/cfc9e9128ed5571d2e36421e347301057662a09e.camel@xxxxxxxxxxxxx/
Fixes: 06cd555f73ca ("net/mlx5: split mlx5_cmd_init() to probe and reload routines")
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
---
Note: I ran into this while testing the linked series for converting
s390x to use dma-iommu. The existing s390x specific DMA API
implementation doesn't respect DMA masks and is thus not affected.
---
Changes in v3:
- Added R-b's from Leon R and Jacob K
- Link to v2: https://lore.kernel.org/r/20230929-mlx5_init_fix-v2-1-51ed2094c9d8@xxxxxxxxxxxxx
---
 drivers/net/ethernet/mellanox/mlx5/core/main.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index 15561965d2af..f251d233a16c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
@@ -250,7 +250,7 @@ static void mlx5_set_driver_version(struct mlx5_core_dev *dev)
 	mlx5_cmd_exec_in(dev, set_driver_version, in);
 }
 
-static int set_dma_caps(struct pci_dev *pdev)
+static int mlx5_dma_init(struct pci_dev *pdev)
 {
 	int err;
 
@@ -905,12 +905,6 @@ static int mlx5_pci_init(struct mlx5_core_dev *dev, struct pci_dev *pdev,
 
 	pci_set_master(pdev);
 
-	err = set_dma_caps(pdev);
-	if (err) {
-		mlx5_core_err(dev, "Failed setting DMA capabilities mask, aborting\n");
-		goto err_clr_master;
-	}
-
 	if (pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP32) &&
 	    pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP64) &&
 	    pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP128))
@@ -1908,9 +1902,15 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto adev_init_err;
 	}
 
+	err = mlx5_dma_init(pdev);
+	if (err) {
+		mlx5_core_err(dev, "Failed setting DMA capabilities mask, aborting\n");
+		goto dma_init_err;
+	}
+
 	err = mlx5_mdev_init(dev, prof_sel);
 	if (err)
-		goto mdev_init_err;
+		goto dma_init_err;
 
 	err = mlx5_pci_init(dev, pdev, id);
 	if (err) {
@@ -1942,7 +1942,7 @@ static int probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	mlx5_pci_close(dev);
 pci_init_err:
 	mlx5_mdev_uninit(dev);
-mdev_init_err:
+dma_init_err:
 	mlx5_adev_idx_free(dev->priv.adev_idx);
 adev_init_err:
 	mlx5_devlink_free(devlink);

---
base-commit: 94f6f0550c625fab1f373bb86a6669b45e9748b3
change-id: 20230928-mlx5_init_fix-c465b5cda327

Best regards,
-- 
Niklas Schnelle