From: Ido Schimmel idosch@nvidia.com
[ 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@d... [2] https://lore.kernel.org/all/20240531213150.GA610983@bhelgaas/
Signed-off-by: Ido Schimmel idosch@nvidia.com Signed-off-by: Petr Machata petrm@nvidia.com Reviewed-by: Przemek Kitszel przemyslaw.kitszel@intel.com Link: https://patch.msgid.link/9937b0afdb50f2f2825945393c94c093c04a5897.1720447210... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 @@ static int mlxsw_pci_reset_at_pci_disable(struct mlxsw_pci *mlxsw_pci,
pci_restore_state(pdev); pci_cfg_access_unlock(pdev); + if (bridge) + pci_cfg_access_unlock(bridge);
return err; }