i40e: use minimal Tx and Rx pairs for kdump

Set the number of the MSI-X vectors to 1. When MSI-X is enabled,
it's not allowed to use more TC queue pairs than MSI-X vectors
(pf->num_lan_msix) exist. Thus the number of Tx and Rx pairs
(vsi->num_queue_pairs) will be equal to the number of MSI-X vectors,
i.e., 1.
Signed-off-by: Coiby Xu <coxu@redhat.com>
Tested-by: Dave Switzer <david.switzer@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -6,6 +6,7 @@
 #include <linux/pci.h>
 #include <linux/bpf.h>
 #include <generated/utsrelease.h>
+#include <linux/crash_dump.h>
 
 /* Local includes */
 #include "i40e.h"
@@ -15506,6 +15507,14 @@ static int i40e_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (err)
 		goto err_switch_setup;
 
+	/* Reduce Tx and Rx pairs for kdump
+	 * When MSI-X is enabled, it's not allowed to use more TC queue
+	 * pairs than MSI-X vectors (pf->num_lan_msix) exist. Thus
+	 * vsi->num_queue_pairs will be equal to pf->num_lan_msix, i.e., 1.
+	 */
+	if (is_kdump_kernel())
+		pf->num_lan_msix = 1;
+
 	pf->udp_tunnel_nic.set_port = i40e_udp_tunnel_set_port;
 	pf->udp_tunnel_nic.unset_port = i40e_udp_tunnel_unset_port;
 	pf->udp_tunnel_nic.flags = UDP_TUNNEL_NIC_INFO_MAY_SLEEP;