sfc: don't try to create more channels than we can have VIs

Calculate efx->max_vis at probe time, and check against it in
 efx_allocate_msix_channels() when considering whether to create XDP TX
 channels.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/ef10.c

@@ -601,10 +601,14 @@ static int efx_ef10_probe(struct efx_nic *efx)
 	 * However, until we use TX option descriptors we need two TX queues
 	 * per channel.
 	 */
-	efx->max_channels = min_t(unsigned int,
-				  EFX_MAX_CHANNELS,
-				  efx_ef10_mem_map_size(efx) /
-				  (efx->vi_stride * EFX_TXQ_TYPES));
+	efx->max_vis = efx_ef10_mem_map_size(efx) / efx->vi_stride;
+	if (!efx->max_vis) {
+		netif_err(efx, drv, efx->net_dev, "error determining max VIs\n");
+		rc = -EIO;
+		goto fail5;
+	}
+	efx->max_channels = min_t(unsigned int, EFX_MAX_CHANNELS,
+				  efx->max_vis / EFX_TXQ_TYPES);
 	efx->max_tx_channels = efx->max_channels;
 	if (WARN_ON(efx->max_channels == 0)) {
 		rc = -EIO;
@@ -1129,6 +1133,12 @@ static int efx_ef10_dimension_resources(struct efx_nic *efx)
 			  ((efx->n_tx_channels + efx->n_extra_tx_channels) *
 			   EFX_TXQ_TYPES) +
 			   efx->n_xdp_channels * efx->xdp_tx_per_channel);
+	if (efx->max_vis && efx->max_vis < channel_vis) {
+		netif_dbg(efx, drv, efx->net_dev,
+			  "Reducing channel VIs from %u to %u\n",
+			  channel_vis, efx->max_vis);
+		channel_vis = efx->max_vis;
+	}
 
 #ifdef EFX_USE_PIO
 	/* Try to allocate PIO buffers if wanted and if the full

drivers/net/ethernet/sfc/efx_channels.c

@@ -175,6 +175,13 @@ static int efx_allocate_msix_channels(struct efx_nic *efx,
 		efx->n_xdp_channels = 0;
 		efx->xdp_tx_per_channel = 0;
 		efx->xdp_tx_queue_count = 0;
+	} else if (n_channels + n_xdp_tx > efx->max_vis) {
+		netif_err(efx, drv, efx->net_dev,
+			  "Insufficient resources for %d XDP TX queues (%d other channels, max VIs %d)\n",
+			  n_xdp_tx, n_channels, efx->max_vis);
+		efx->n_xdp_channels = 0;
+		efx->xdp_tx_per_channel = 0;
+		efx->xdp_tx_queue_count = 0;
 	} else {
 		efx->n_xdp_channels = n_xdp_ev;
 		efx->xdp_tx_per_channel = EFX_TXQ_TYPES;

drivers/net/ethernet/sfc/net_driver.h

@@ -1022,6 +1022,7 @@ struct efx_nic {
 	unsigned next_buffer_table;
 
 	unsigned int max_channels;
+	unsigned int max_vis;
 	unsigned int max_tx_channels;
 	unsigned n_channels;
 	unsigned n_rx_channels;

drivers/net/ethernet/sfc/siena.c

@@ -276,6 +276,7 @@ static int siena_probe_nic(struct efx_nic *efx)
 	}
 
 	efx->max_channels = EFX_MAX_CHANNELS;
+	efx->max_vis = EFX_MAX_CHANNELS;
 	efx->max_tx_channels = EFX_MAX_CHANNELS;
 
 	efx_reado(efx, &reg, FR_AZ_CS_DEBUG);