From: Parav Pandit <parav@mellanox.com>
Date: Mon, 28 Oct 2019 13:29:17 -0500
Subject: net/mlx5: Read num_vfs before disabling SR-IOV
Patch-mainline: v5.5-rc1
Git-commit: a7cba0a4d508d2d78f2932ee944feadd38c97c2c
References: jsc#SLE-8464

mlx5_device_disable_sriov() currently reads num_vfs from the PCI core.
However when mlx5_device_disable_sriov() is executed, SR-IOV is
already disabled at the PCI level.
Due to this disable_hca() cleanup is not done during SR-IOV disable
flow.

mlx5_sriov_disable()
  pci_enable_sriov()
  mlx5_device_disable_sriov() <- num_vfs is zero here.

When SR-IOV enablement fails during mlx5_sriov_enable(), HCA's are left
in enabled stage because mlx5_device_disable_sriov() relies on num_vfs
from PCI core.

mlx5_sriov_enable()
  mlx5_device_enable_sriov()
  pci_enable_sriov() <- Fails

Hence, to overcome above issues,
(a) Read num_vfs before disabling SR-IOV and use it.
(b) Use num_vfs given when enabling sriov in error unwinding path.

Fixes: d886aba677a0 ("net/mlx5: Reduce dependency on enabled_vfs counter and num_vfs")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/sriov.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/sriov.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/sriov.c
@@ -108,10 +108,10 @@ enable_vfs_hca:
 	return 0;
 }
 
-static void mlx5_device_disable_sriov(struct mlx5_core_dev *dev, bool clear_vf)
+static void
+mlx5_device_disable_sriov(struct mlx5_core_dev *dev, int num_vfs, bool clear_vf)
 {
 	struct mlx5_core_sriov *sriov = &dev->priv.sriov;
-	int num_vfs = pci_num_vf(dev->pdev);
 	int err;
 	int vf;
 
@@ -147,7 +147,7 @@ static int mlx5_sriov_enable(struct pci_
 	err = pci_enable_sriov(pdev, num_vfs);
 	if (err) {
 		mlx5_core_warn(dev, "pci_enable_sriov failed : %d\n", err);
-		mlx5_device_disable_sriov(dev, true);
+		mlx5_device_disable_sriov(dev, num_vfs, true);
 	}
 	return err;
 }
@@ -155,9 +155,10 @@ static int mlx5_sriov_enable(struct pci_
 static void mlx5_sriov_disable(struct pci_dev *pdev)
 {
 	struct mlx5_core_dev *dev  = pci_get_drvdata(pdev);
+	int num_vfs = pci_num_vf(dev->pdev);
 
 	pci_disable_sriov(pdev);
-	mlx5_device_disable_sriov(dev, true);
+	mlx5_device_disable_sriov(dev, num_vfs, true);
 }
 
 int mlx5_core_sriov_configure(struct pci_dev *pdev, int num_vfs)
@@ -192,7 +193,7 @@ void mlx5_sriov_detach(struct mlx5_core_
 	if (!mlx5_core_is_pf(dev))
 		return;
 
-	mlx5_device_disable_sriov(dev, false);
+	mlx5_device_disable_sriov(dev, pci_num_vf(dev->pdev), false);
 }
 
 static u16 mlx5_get_max_vfs(struct mlx5_core_dev *dev)