net/mlx5: fw reset, check bridge accessibility at earlier stage

JIRA: https://issues.redhat.com/browse/RHEL-72227
JIRA: https://issues.redhat.com/browse/RHEL-73520
Upstream-status: v6.15-rc1

commit ade4794
Author: Amir Tzin <amirtz@nvidia.com>
Date:   Wed Mar 19 16:03:00 2025 +0200

    net/mlx5: fw reset, check bridge accessibility at earlier stage

    Currently, mlx5_is_reset_now_capable() checks whether the pci bridge is
    accessible only on bridge hot plug capability check.  If the pci bridge
    is not accessible, reset now will fail regardless of bridge hotplug
    capability. Move this check to function mlx5_is_reset_now_capable()
    which, in such case, aborts the reset and does so in the request phase
    instead of the reset now phase.

    Signed-off-by: Aya Levin <ayal@nvidia.com>
    Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
    Signed-off-by: Amir Tzin <amirtz@nvidia.com>
    Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
    Link: https://patch.msgid.link/1742392983-153050-3-git-send-email-tariqt@nvidia.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Benjamin Poirier <bpoirier@redhat.com>

Author: Benjamin Poirier

drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c

@@ -345,15 +345,12 @@ static void mlx5_fw_live_patch_event(struct work_struct *work)
 }
 
 #if IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE)
-static int mlx5_check_hotplug_interrupt(struct mlx5_core_dev *dev)
+static int mlx5_check_hotplug_interrupt(struct mlx5_core_dev *dev,
+					struct pci_dev *bridge)
 {
-	struct pci_dev *bridge = dev->pdev->bus->self;
 	u16 reg16;
 	int err;
 
-	if (!bridge)
-		return -EOPNOTSUPP;
-
 	err = pcie_capability_read_word(bridge, PCI_EXP_SLTCTL, &reg16);
 	if (err)
 		return err;
@@ -416,17 +413,23 @@ static int mlx5_check_dev_ids(struct mlx5_core_dev *dev, u16 dev_id)
 static bool mlx5_is_reset_now_capable(struct mlx5_core_dev *dev,
 				      u8 reset_method)
 {
+	struct pci_dev *bridge = dev->pdev->bus->self;
 	u16 dev_id;
 	int err;
 
+	if (!bridge) {
+		mlx5_core_warn(dev, "PCI bus bridge is not accessible\n");
+		return false;
+	}
+
 	if (!MLX5_CAP_GEN(dev, fast_teardown)) {
 		mlx5_core_warn(dev, "fast teardown is not supported by firmware\n");
 		return false;
 	}
 
 #if IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE)
 	if (reset_method != MLX5_MFRL_REG_PCI_RESET_METHOD_HOT_RESET) {
-		err = mlx5_check_hotplug_interrupt(dev);
+		err = mlx5_check_hotplug_interrupt(dev, bridge);
 		if (err)
 			return false;
 	}