From ff012dd4b5ae32a9ae34eced554a26d2ca32ad5a Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 8 Jul 2024 16:23:42 +0200 Subject: [PATCH] mlxsw: pci: Lock configuration space of upstream bridge during reset [ Upstream commit 0970836c348b6bc2ea77ce4348a136d6febfd440 ] The driver triggers a "Secondary Bus Reset" (SBR) by calling __pci_reset_function_locked() which asserts the SBR bit in the "Bridge Control Register" in the configuration space of the upstream bridge for 2ms. This is done without locking the configuration space of the upstream bridge port, allowing user space to access it concurrently. Linux 6.11 will start warning about such unlocked resets [1][2]: pcieport 0000:00:01.0: unlocked secondary bus reset via: pci_reset_bus_function+0x51c/0x6a0 Avoid the warning and the concurrent access by locking the configuration space of the upstream bridge prior to the reset and unlocking it afterwards. [1] https://lore.kernel.org/all/171711746953.1628941.4692125082286867825.stgit@dwillia2-xfh.jf.intel.com/ [2] https://lore.kernel.org/all/20240531213150.GA610983@bhelgaas/ Signed-off-by: Ido Schimmel Signed-off-by: Petr Machata Reviewed-by: Przemek Kitszel Link: https://patch.msgid.link/9937b0afdb50f2f2825945393c94c093c04a5897.1720447210.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/mellanox/mlxsw/pci.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c index c0ced4d315f3d..d92f640bae575 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/pci.c +++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c @@ -1599,6 +1599,7 @@ static int mlxsw_pci_reset_at_pci_disable(struct mlxsw_pci *mlxsw_pci, { struct pci_dev *pdev = mlxsw_pci->pdev; char mrsr_pl[MLXSW_REG_MRSR_LEN]; + struct pci_dev *bridge; int err; if (!pci_reset_sbr_supported) { @@ -1615,6 +1616,9 @@ static int mlxsw_pci_reset_at_pci_disable(struct mlxsw_pci *mlxsw_pci, sbr: device_lock_assert(&pdev->dev); + bridge = pci_upstream_bridge(pdev); + if (bridge) + pci_cfg_access_lock(bridge); pci_cfg_access_lock(pdev); pci_save_state(pdev); @@ -1624,6 +1628,8 @@ sbr: pci_restore_state(pdev); pci_cfg_access_unlock(pdev); + if (bridge) + pci_cfg_access_unlock(bridge); return err; } -- 2.47.3