[PATCH net] ice: always add legacy 32byte RXDID in supported_rxdids

[Michal Schmidt <mschmidt@redhat.com>]

When the PF and VF drivers both support flexible rx descriptors and have
negotiated the VIRTCHNL_VF_OFFLOAD_RX_FLEX_DESC capability, the VF driver
queries the PF for the list of supported descriptor formats
(VIRTCHNL_OP_GET_SUPPORTED_RXDIDS). The PF driver is supposed to set the
supported_rxdids bits that correspond to the descriptor formats the
firmware implements. The legacy 32-byte rx desc format is always
supported, even though it is not expressed in GLFLXP_RXDID_FLAGS.

The ice driver does not advertise the legacy 32-byte rx desc support,
which leads to this failure to bring up the VF using the Intel
out-of-tree iavf driver:
 iavf 0000:41:01.0: PF does not list support for default Rx descriptor format
 ...
 iavf 0000:41:01.0: PF returned error -5 (VIRTCHNL_STATUS_ERR_PARAM) to our request 6

The in-tree iavf driver does not expose this bug, because it does not
yet implement VIRTCHNL_VF_OFFLOAD_RX_FLEX_DESC.

The ice driver must always set the ICE_RXDID_LEGACY_1 bit in
supported_rxdids. The Intel out-of-tree ice driver and the ice driver in
DPDK both do this.

I copied this piece of the code and the comment text from the Intel
out-of-tree driver.

Fixes: e753df8fbca5 ("ice: Add support Flex RXD")
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice_virtchnl.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_virtchnl.c b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
index b03426ac932b..db97353efd06 100644
--- a/drivers/net/ethernet/intel/ice/ice_virtchnl.c
+++ b/drivers/net/ethernet/intel/ice/ice_virtchnl.c
@@ -2617,12 +2617,14 @@ static int ice_vc_query_rxdid(struct ice_vf *vf)
 		goto err;
 	}
 
-	/* Read flexiflag registers to determine whether the
-	 * corresponding RXDID is configured and supported or not.
-	 * Since Legacy 16byte descriptor format is not supported,
-	 * start from Legacy 32byte descriptor.
+	/* RXDIDs supported by DDP package can be read from the register
+	 * to get the supported RXDID bitmap. But the legacy 32byte RXDID
+	 * is not listed in DDP package, add it in the bitmap manually.
+	 * Legacy 16byte descriptor is not supported.
 	 */
-	for (i = ICE_RXDID_LEGACY_1; i < ICE_FLEX_DESC_RXDID_MAX_NUM; i++) {
+	rxdid->supported_rxdids |= BIT(ICE_RXDID_LEGACY_1);
+
+	for (i = ICE_RXDID_FLEX_NIC; i < ICE_FLEX_DESC_RXDID_MAX_NUM; i++) {
 		regval = rd32(hw, GLFLXP_RXDID_FLAGS(i, 0));
 		if ((regval >> GLFLXP_RXDID_FLAGS_FLEXIFLAG_4N_S)
 			& GLFLXP_RXDID_FLAGS_FLEXIFLAG_4N_M)
-- 
2.41.0