[PATCH v3 5/6] common/sfc_efx/base: deny periodic MAC stats delivery to VFs

Currently, requesting periodic DMA results in an EACCES error being
returned, but the DPDK driver expects ENOTSUP to handle the
situation gracefully. Implement proper error indication.

Signed-off-by: Ivan Malov <[email protected]>
Reviewed-by: Andy Moreton <[email protected]>
---
 drivers/common/sfc_efx/base/efx_np.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/common/sfc_efx/base/efx_np.c b/drivers/common/sfc_efx/base/efx_np.c
index a13d89332c..0cdedbfbe4 100644
--- a/drivers/common/sfc_efx/base/efx_np.c
+++ b/drivers/common/sfc_efx/base/efx_np.c
@@ -1734,16 +1734,32 @@ efx_np_mac_stats(
 	efx_mcdi_execute(enp, &req);
 
 	if (req.emr_rc != 0) {
+		const efx_nic_cfg_t *encp = &enp->en_nic_cfg;
+
+		if (req.emr_rc == EACCES && (enable | events) &&
+		    EFX_PCI_FUNCTION_IS_VF(encp)) {
+			/*
+			 * VFs cannot request periodic DMAing of statistics.
+			 * Indicate 'ENOTSUP' for the DPDK driver to handle
+			 * this gracefully and stick with one-time uploads.
+			 */
+			rc = ENOTSUP;
+			goto fail3;
+		}
+
 		/* EF10: Expect ENOENT if no DMA queues are initialised */
 		if ((req.emr_rc != ENOENT) ||
 		    (enp->en_rx_qcount + enp->en_tx_qcount != 0)) {
 			rc = req.emr_rc;
-			goto fail3;
+			goto fail4;
 		}
 	}
 
 	return (0);
 
+fail4:
+	EFSYS_PROBE(fail4);
+
 fail3:
 	EFSYS_PROBE(fail3);
 
-- 
2.47.3