netdev - [next-queue RFC 1/4] ethtool: Add support for configuring frame preemption

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Date:   Fri, 15 May 2020 18:29:45 -0700
From:   Vinicius Costa Gomes <vinicius.gomes@...el.com>
To:     intel-wired-lan@...ts.osuosl.org
Cc:     Vinicius Costa Gomes <vinicius.gomes@...el.com>,
        jeffrey.t.kirsher@...el.com, netdev@...r.kernel.org,
        vladimir.oltean@....com, po.liu@....com, m-karicheri2@...com,
        Jose.Abreu@...opsys.com
Subject: [next-queue RFC 1/4] ethtool: Add support for configuring frame preemption

Frame preemption (described in IEEE 802.3br-2016) defines the concept
of preemptible and express queues. It allows traffic from express
queues to "interrupt" traffic from preemptible queues, which are
"resumed" after the express traffic has finished transmitting.

Frame preemption can only be used when both the local device and the
link partner support it.

A new ethtool command was added to support the configuration
parameters.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
---
 include/linux/ethtool.h      |  6 ++++++
 include/uapi/linux/ethtool.h | 25 +++++++++++++++++++++++++
 net/ethtool/ioctl.c          | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index a23b26e..e4a6710 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -360,6 +360,8 @@ bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
  * @get_ethtool_phy_stats: Return extended statistics about the PHY device.
  *	This is only useful if the device maintains PHY statistics and
  *	cannot use the standard PHY library helpers.
+ * @get_preempt: Get the network device Frame Preemption parameters.
+ * @set_preempt: Set the network device Frame Preemption parameters.
  *
  * All operations are optional (i.e. the function pointer may be set
  * to %NULL) and callers must take this into account.  Callers must
@@ -454,6 +456,10 @@ struct ethtool_ops {
 				      struct ethtool_fecparam *);
 	int	(*set_fecparam)(struct net_device *,
 				      struct ethtool_fecparam *);
+	int	(*get_preempt)(struct net_device *,
+			       struct ethtool_fp *);
+	int	(*set_preempt)(struct net_device *,
+			       struct ethtool_fp *);
 	void	(*get_ethtool_phy_stats)(struct net_device *,
 					 struct ethtool_stats *, u64 *);
 };
diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index f4662b3..d63f9f8 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -369,6 +369,28 @@ struct ethtool_eee {
 	__u32	reserved[2];
 };
 
+/**
+ * struct ethtool_fp - Frame Preemption information
+ * @cmd: ETHTOOL_{G,S}FP
+ * @fp_supported: If frame preemption is supported.
+ * @fp_enabled: If frame preemption should be advertised to the link partner
+ *	as enabled.
+ * @supported_queues_mask: Bitmask indicating which queues support being
+ *	configured as preemptible (bit 0 -> queue 0, bit N -> queue N).
+ * @preemptible_queues_mask: Bitmask indicating which queues are
+ *	configured as preemptible (bit 0 -> queue 0, bit N -> queue N).
+ * @min_frag_size: Minimum size for all non-final fragment size.
+ */
+struct ethtool_fp {
+	__u32	cmd;
+	__u8	fp_supported;
+	__u8	fp_enabled;
+	__u32	supported_queues_mask;
+	__u32	preemptible_queues_mask;
+	__u32	min_frag_size;
+	__u32	reserved[2];
+};
+
 /**
  * struct ethtool_modinfo - plugin module eeprom information
  * @cmd: %ETHTOOL_GMODULEINFO
@@ -1441,6 +1463,9 @@ enum ethtool_fec_config_bits {
 #define ETHTOOL_GFECPARAM	0x00000050 /* Get FEC settings */
 #define ETHTOOL_SFECPARAM	0x00000051 /* Set FEC settings */
 
+#define ETHTOOL_GFP		0x00000052 /* Get Frame Preemption settings */
+#define ETHTOOL_SFP		0x00000053 /* Set Frame Preemption settings */
+
 /* compatibility with older code */
 #define SPARC_ETH_GSET		ETHTOOL_GSET
 #define SPARC_ETH_SSET		ETHTOOL_SSET
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 52102ab..e15ad5c 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -2531,6 +2531,36 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
 	return dev->ethtool_ops->set_fecparam(dev, &fecparam);
 }
 
+static int ethtool_get_preempt(struct net_device *dev, void __user *useraddr)
+{
+	struct ethtool_fp fpparam = { .cmd = ETHTOOL_GFP };
+	int rc;
+
+	if (!dev->ethtool_ops->get_preempt)
+		return -EOPNOTSUPP;
+
+	rc = dev->ethtool_ops->get_preempt(dev, &fpparam);
+	if (rc)
+		return rc;
+
+	if (copy_to_user(useraddr, &fpparam, sizeof(fpparam)))
+		return -EFAULT;
+	return 0;
+}
+
+static int ethtool_set_preempt(struct net_device *dev, void __user *useraddr)
+{
+	struct ethtool_fp fpparam;
+
+	if (!dev->ethtool_ops->set_preempt)
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&fpparam, useraddr, sizeof(fpparam)))
+		return -EFAULT;
+
+	return dev->ethtool_ops->set_preempt(dev, &fpparam);
+}
+
 /* The main entry point in this file.  Called from net/core/dev_ioctl.c */
 
 int dev_ethtool(struct net *net, struct ifreq *ifr)
@@ -2810,6 +2840,12 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_SFECPARAM:
 		rc = ethtool_set_fecparam(dev, useraddr);
 		break;
+	case ETHTOOL_GFP:
+		rc = ethtool_get_preempt(dev, useraddr);
+		break;
+	case ETHTOOL_SFP:
+		rc = ethtool_set_preempt(dev, useraddr);
+		break;
 	default:
 		rc = -EOPNOTSUPP;
 	}
-- 
2.26.2