From 9a87c3fca2372af3177cb454c7aa381c7080307f Mon Sep 17 00:00:00 2001

From: "Dwip N. Banerjee" <dnbanerg@us.ibm.com>

Date: Wed, 18 Nov 2020 19:12:22 -0600

Subject: [PATCH] ibmvnic: Ensure that device queue memory is cache-line

 aligned

References: bsc#1184114 ltc#192237 bsc#1179243 ltc#189290

Patch-mainline: v5.11-rc1

Git-commit: 9a87c3fca2372af3177cb454c7aa381c7080307f

PCI bus slowdowns were observed on IBM VNIC devices as a result

of partial cache line writes and non-cache aligned full cache line writes.

Ensure that packet data buffers are cache-line aligned to avoid these

slowdowns.

Signed-off-by: Dwip N. Banerjee <dnbanerg@us.ibm.com>

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 drivers/net/ethernet/ibm/ibmvnic.c |  9 ++++++---

 drivers/net/ethernet/ibm/ibmvnic.h | 10 +++++-----

 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c

index e9b0cb6dfd9d..85df91c9861b 100644

--- a/drivers/net/ethernet/ibm/ibmvnic.c

+++ b/drivers/net/ethernet/ibm/ibmvnic.c

@@ -498,7 +498,7 @@ static int reset_rx_pools(struct ibmvnic_adapter *adapter)

 		if (rx_pool->buff_size != buff_size) {

 			free_long_term_buff(adapter, &rx_pool->long_term_buff);

-			rx_pool->buff_size = buff_size;

+			rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

 			rc = alloc_long_term_buff(adapter,

 						  &rx_pool->long_term_buff,

 						  rx_pool->size *

@@ -592,7 +592,7 @@ static int init_rx_pools(struct net_device *netdev)

 		rx_pool->size = adapter->req_rx_add_entries_per_subcrq;

 		rx_pool->index = i;

-		rx_pool->buff_size = buff_size;

+		rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

 		rx_pool->active = 1;

 		rx_pool->free_map = kcalloc(rx_pool->size, sizeof(int),

@@ -745,6 +745,7 @@ static int init_tx_pools(struct net_device *netdev)

 {

 	struct ibmvnic_adapter *adapter = netdev_priv(netdev);

 	int tx_subcrqs;

+	u64 buff_size;

 	int i, rc;

 	tx_subcrqs = adapter->num_active_tx_scrqs;

@@ -761,9 +762,11 @@ static int init_tx_pools(struct net_device *netdev)

 	adapter->num_active_tx_pools = tx_subcrqs;

 	for (i = 0; i < tx_subcrqs; i++) {

+		buff_size = adapter->req_mtu + VLAN_HLEN;

+		buff_size = ALIGN(buff_size, L1_CACHE_BYTES);

 		rc = init_one_tx_pool(netdev, &adapter->tx_pool[i],

 				      adapter->req_tx_entries_per_subcrq,

-				      adapter->req_mtu + VLAN_HLEN);

+				      buff_size);

 		if (rc) {

 			release_tx_pools(adapter);

 			return rc;

diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h

index 16d892c3db0f..9911d926dd7f 100644

--- a/drivers/net/ethernet/ibm/ibmvnic.h

+++ b/drivers/net/ethernet/ibm/ibmvnic.h

@@ -883,7 +883,7 @@ struct ibmvnic_sub_crq_queue {

 	atomic_t used;

 	char name[32];

 	u64 handle;

-};

+} ____cacheline_aligned;

 struct ibmvnic_long_term_buff {

 	unsigned char *buff;

@@ -907,7 +907,7 @@ struct ibmvnic_tx_pool {

 	struct ibmvnic_long_term_buff long_term_buff;

 	int num_buffers;

 	int buf_size;

-};

+} ____cacheline_aligned;

 struct ibmvnic_rx_buff {

 	struct sk_buff *skb;

@@ -928,7 +928,7 @@ struct ibmvnic_rx_pool {

 	int next_alloc;

 	int active;

 	struct ibmvnic_long_term_buff long_term_buff;

-};

+} ____cacheline_aligned;

 struct ibmvnic_vpd {

 	unsigned char *buff;

@@ -1015,8 +1015,8 @@ struct ibmvnic_adapter {

 	atomic_t running_cap_crqs;

 	bool wait_capability;

-	struct ibmvnic_sub_crq_queue **tx_scrq;

-	struct ibmvnic_sub_crq_queue **rx_scrq;

+	struct ibmvnic_sub_crq_queue **tx_scrq ____cacheline_aligned;

+	struct ibmvnic_sub_crq_queue **rx_scrq ____cacheline_aligned;

 	/* rx structs */

 	struct napi_struct *napi;

-- 

2.26.2