qed: Fix QM getters to always return a valid pq

The getter callers doesn't know the valid Physical Queues (PQ) values.
This patch makes sure that a valid PQ will always be returned.

The patch consists of 3 fixes:

 - When qed_init_qm_get_idx_from_flags() receives a disabled flag, it
   returned PQ 0, which can potentially be another function's pq. Verify
   that flag is enabled, otherwise return default start_pq.

 - When qed_init_qm_get_idx_from_flags() receives an unknown flag, it
   returned NULL and could lead to a segmentation fault. Return default
   start_pq instead.

 - A modulo operation was added to MCOS/VFS PQ getters to make sure the
   PQ returned is in range of the required flag.

Fixes: b5a9ee7c ("qed: Revise QM cofiguration")
Signed-off-by: Denis Bolotin <denis.bolotin@cavium.com>
Signed-off-by: Michal Kalderon <michal.kalderon@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_dev.c

@@ -491,6 +491,11 @@ static u16 *qed_init_qm_get_idx_from_flags(struct qed_hwfn *p_hwfn,
 		goto err;
 	}
 
+	if (!(qed_get_pq_flags(p_hwfn) & pq_flags)) {
+		DP_ERR(p_hwfn, "pq flag 0x%x is not set\n", pq_flags);
+		goto err;
+	}
+
 	switch (pq_flags) {
 	case PQ_FLAGS_RLS:
 		return &qm_info->first_rl_pq;
@@ -513,8 +518,7 @@ static u16 *qed_init_qm_get_idx_from_flags(struct qed_hwfn *p_hwfn,
 	}
 
 err:
-	DP_ERR(p_hwfn, "BAD pq flags %d\n", pq_flags);
-	return NULL;
+	return &qm_info->start_pq;
 }
 
 /* save pq index in qm info */
@@ -538,20 +542,32 @@ u16 qed_get_cm_pq_idx_mcos(struct qed_hwfn *p_hwfn, u8 tc)
 {
 	u8 max_tc = qed_init_qm_get_num_tcs(p_hwfn);
 
+	if (max_tc == 0) {
+		DP_ERR(p_hwfn, "pq with flag 0x%lx do not exist\n",
+		       PQ_FLAGS_MCOS);
+		return p_hwfn->qm_info.start_pq;
+	}
+
 	if (tc > max_tc)
 		DP_ERR(p_hwfn, "tc %d must be smaller than %d\n", tc, max_tc);
 
-	return qed_get_cm_pq_idx(p_hwfn, PQ_FLAGS_MCOS) + tc;
+	return qed_get_cm_pq_idx(p_hwfn, PQ_FLAGS_MCOS) + (tc % max_tc);
 }
 
 u16 qed_get_cm_pq_idx_vf(struct qed_hwfn *p_hwfn, u16 vf)
 {
 	u16 max_vf = qed_init_qm_get_num_vfs(p_hwfn);
 
+	if (max_vf == 0) {
+		DP_ERR(p_hwfn, "pq with flag 0x%lx do not exist\n",
+		       PQ_FLAGS_VFS);
+		return p_hwfn->qm_info.start_pq;
+	}
+
 	if (vf > max_vf)
 		DP_ERR(p_hwfn, "vf %d must be smaller than %d\n", vf, max_vf);
 
-	return qed_get_cm_pq_idx(p_hwfn, PQ_FLAGS_VFS) + vf;
+	return qed_get_cm_pq_idx(p_hwfn, PQ_FLAGS_VFS) + (vf % max_vf);
 }
 
 u16 qed_get_cm_pq_idx_ofld_mtc(struct qed_hwfn *p_hwfn, u8 tc)