[PATCH 4/6] common/sfc_efx/base: deny tuning FCS and flow control to VFs

[Ivan Malov <ivan.malov@arknetworks.am>]

Medford4 VFs can configure MAC settings via the netport MCDI,
but controlling FCS stripping and setting flow control mode
are off limits. Express all this in code to allow the DPDK
driver to start and forbid changes to FCS and flow control.

For what it's worth, changing MTU is allowed on VFs, but
the value must be less than or equal to the PF's MTU.

Signed-off-by: Ivan Malov <ivan.malov@arknetworks.am>
Reviewed-by: Andy Moreton <andy.moreton@amd.com>
---
 drivers/common/sfc_efx/base/efx_np.c | 41 +++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/drivers/common/sfc_efx/base/efx_np.c b/drivers/common/sfc_efx/base/efx_np.c
index 1563fbae37..6d9c62fcda 100644
--- a/drivers/common/sfc_efx/base/efx_np.c
+++ b/drivers/common/sfc_efx/base/efx_np.c
@@ -1548,6 +1548,7 @@ efx_np_mac_ctrl(
 	__in		efx_np_handle_t nph,
 	__in		const efx_np_mac_ctrl_t *mc)
 {
+	const efx_nic_cfg_t *encp = &enp->en_nic_cfg;
 	EFX_MCDI_DECLARE_BUF(payload,
 	    MC_CMD_MAC_CTRL_IN_LEN,
 	    MC_CMD_MAC_CTRL_OUT_LEN);
@@ -1571,9 +1572,19 @@ efx_np_mac_ctrl(
 	if (mc->enmc_set_pdu_only != B_FALSE)
 		goto skip_full_reconfigure;
 
-	cfg |= 1U << MC_CMD_MAC_CONFIG_OPTIONS_CFG_INCLUDE_FCS;
-	if (mc->enmc_include_fcs != B_FALSE)
-		flags |= 1U << MC_CMD_MAC_FLAGS_FLAG_INCLUDE_FCS;
+	/* Only PFs can control FCS stripping. */
+	if (EFX_PCI_FUNCTION_IS_PF(encp)) {
+		cfg |= 1U << MC_CMD_MAC_CONFIG_OPTIONS_CFG_INCLUDE_FCS;
+		if (mc->enmc_include_fcs != B_FALSE)
+			flags |= 1U << MC_CMD_MAC_FLAGS_FLAG_INCLUDE_FCS;
+	} else if (mc->enmc_include_fcs != B_FALSE) {
+		/*
+		 * Assume that FCS stripping being enabled is the driver's
+		 * default expectation and deny disabling it to VFs.
+		 */
+		rc = ENOTSUP;
+		goto fail1;
+	}
 
 	MCDI_IN_SET_DWORD(req, MAC_CTRL_IN_FLAGS, flags);
 
@@ -1595,12 +1606,22 @@ efx_np_mac_ctrl(
 			break;
 		default:
 			rc = EINVAL;
-			goto fail1;
+			goto fail2;
 		}
 	}
 
-	cfg |= 1U << MC_CMD_MAC_CONFIG_OPTIONS_CFG_FCNTL;
-	MCDI_IN_SET_DWORD(req, MAC_CTRL_IN_FCNTL, fcntl);
+	/* Only PFs can change flow control settings. */
+	if (EFX_PCI_FUNCTION_IS_PF(encp)) {
+		cfg |= 1U << MC_CMD_MAC_CONFIG_OPTIONS_CFG_FCNTL;
+		MCDI_IN_SET_DWORD(req, MAC_CTRL_IN_FCNTL, fcntl);
+	} else if (fcntl != MC_CMD_FCNTL_AUTO) {
+		/*
+		 * Assume that flow control auto-negotiation is the driver's
+		 * default expectation and deny any attempts to override it.
+		 */
+		rc = ENOTSUP;
+		goto fail3;
+	}
 
 skip_full_reconfigure:
 	MCDI_IN_SET_DWORD(req, MAC_CTRL_IN_V2_CONTROL_FLAGS, cfg);
@@ -1609,11 +1630,17 @@ efx_np_mac_ctrl(
 
 	if (req.emr_rc != 0) {
 		rc = req.emr_rc;
-		goto fail2;
+		goto fail4;
 	}
 
 	return (0);
 
+fail4:
+	EFSYS_PROBE(fail4);
+
+fail3:
+	EFSYS_PROBE(fail3);
+
 fail2:
 	EFSYS_PROBE(fail2);
 
-- 
2.47.3