[PATCH net-next 5/5] gve: Remove dependency on 4k page size.

[John Fraker <jfraker@google.com>]

Prior to this change, gve crashes when attempting to run in kernels with
page sizes other than 4k. This change removes unnecessary references to
PAGE_SIZE and replaces them with more meaningful constants.

Signed-off-by: Jordan Kimbrough <jrkim@google.com>
Signed-off-by: John Fraker <jfraker@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
---
 drivers/net/ethernet/google/gve/gve.h         | 4 +++-
 drivers/net/ethernet/google/gve/gve_ethtool.c | 2 +-
 drivers/net/ethernet/google/gve/gve_main.c    | 4 ++--
 drivers/net/ethernet/google/gve/gve_rx.c      | 9 ++++-----
 drivers/net/ethernet/google/gve/gve_tx.c      | 2 +-
 5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index abc0c708b..b80349154 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -49,7 +49,9 @@
 /* PTYPEs are always 10 bits. */
 #define GVE_NUM_PTYPES	1024
 
-#define GVE_RX_BUFFER_SIZE_DQO 2048
+#define GVE_DEFAULT_RX_BUFFER_SIZE 2048
+
+#define GVE_DEFAULT_RX_BUFFER_OFFSET 2048
 
 #define GVE_XDP_ACTIONS 5
 
diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index 233e59469..e5397aa1e 100644
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -519,7 +519,7 @@ static int gve_set_tunable(struct net_device *netdev,
 	case ETHTOOL_RX_COPYBREAK:
 	{
 		u32 max_copybreak = gve_is_gqi(priv) ?
-			(PAGE_SIZE / 2) : priv->data_buffer_size_dqo;
+			GVE_DEFAULT_RX_BUFFER_SIZE : priv->data_buffer_size_dqo;
 
 		len = *(u32 *)value;
 		if (len > max_copybreak)
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index cc169748f..619bf63ec 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -1328,7 +1328,7 @@ static int gve_open(struct net_device *dev)
 		/* Hard code this for now. This may be tuned in the future for
 		 * performance.
 		 */
-		priv->data_buffer_size_dqo = GVE_RX_BUFFER_SIZE_DQO;
+		priv->data_buffer_size_dqo = GVE_DEFAULT_RX_BUFFER_SIZE;
 	}
 	err = gve_create_rings(priv);
 	if (err)
@@ -1664,7 +1664,7 @@ static int verify_xdp_configuration(struct net_device *dev)
 		return -EOPNOTSUPP;
 	}
 
-	if (dev->mtu > (PAGE_SIZE / 2) - sizeof(struct ethhdr) - GVE_RX_PAD) {
+	if (dev->mtu > GVE_DEFAULT_RX_BUFFER_SIZE - sizeof(struct ethhdr) - GVE_RX_PAD) {
 		netdev_warn(dev, "XDP is not supported for mtu %d.\n",
 			    dev->mtu);
 		return -EOPNOTSUPP;
diff --git a/drivers/net/ethernet/google/gve/gve_rx.c b/drivers/net/ethernet/google/gve/gve_rx.c
index 3d6b26ac6..3cb3a9ac6 100644
--- a/drivers/net/ethernet/google/gve/gve_rx.c
+++ b/drivers/net/ethernet/google/gve/gve_rx.c
@@ -282,7 +282,7 @@ static int gve_rx_alloc_ring(struct gve_priv *priv, int idx)
 	/* Allocating half-page buffers allows page-flipping which is faster
 	 * than copying or allocating new pages.
 	 */
-	rx->packet_buffer_size = PAGE_SIZE / 2;
+	rx->packet_buffer_size = GVE_DEFAULT_RX_BUFFER_SIZE;
 	gve_rx_ctx_clear(&rx->ctx);
 	gve_rx_add_to_block(priv, idx);
 
@@ -398,10 +398,10 @@ static struct sk_buff *gve_rx_add_frags(struct napi_struct *napi,
 
 static void gve_rx_flip_buff(struct gve_rx_slot_page_info *page_info, __be64 *slot_addr)
 {
-	const __be64 offset = cpu_to_be64(PAGE_SIZE / 2);
+	const __be64 offset = cpu_to_be64(GVE_DEFAULT_RX_BUFFER_OFFSET);
 
 	/* "flip" to other packet buffer on this page */
-	page_info->page_offset ^= PAGE_SIZE / 2;
+	page_info->page_offset ^= GVE_DEFAULT_RX_BUFFER_OFFSET;
 	*(slot_addr) ^= offset;
 }
 
@@ -506,8 +506,7 @@ static struct sk_buff *gve_rx_copy_to_pool(struct gve_rx_ring *rx,
 		return NULL;
 
 	gve_dec_pagecnt_bias(copy_page_info);
-	copy_page_info->page_offset += rx->packet_buffer_size;
-	copy_page_info->page_offset &= (PAGE_SIZE - 1);
+	copy_page_info->page_offset ^= GVE_DEFAULT_RX_BUFFER_OFFSET;
 
 	if (copy_page_info->can_flip) {
 		/* We have used both halves of this copy page, it
diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c
index 9f6ffc4a5..07ba12478 100644
--- a/drivers/net/ethernet/google/gve/gve_tx.c
+++ b/drivers/net/ethernet/google/gve/gve_tx.c
@@ -819,7 +819,7 @@ int gve_xdp_xmit_one(struct gve_priv *priv, struct gve_tx_ring *tx,
 	return 0;
 }
 
-#define GVE_TX_START_THRESH	PAGE_SIZE
+#define GVE_TX_START_THRESH	4096
 
 static int gve_clean_tx_done(struct gve_priv *priv, struct gve_tx_ring *tx,
 			     u32 to_do, bool try_to_wake)
-- 
2.43.0.rc1.413.gea7ed67945-goog