1 files changed, 701 insertions, 23 deletions

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 39e094907391..bfc024024aa3 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -26,6 +26,7 @@
 #include <linux/bitops.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <net/drop_monitor.h>
 #include <net/genetlink.h>
 #include <net/netevent.h>
 
@@ -43,6 +44,7 @@
  * netlink alerts
  */
 static int trace_state = TRACE_OFF;
+static bool monitor_hw;
 
 /* net_dm_mutex
  *
@@ -56,9 +58,26 @@ struct net_dm_stats {
         struct u64_stats_sync syncp;
 };
 
+#define NET_DM_MAX_HW_TRAP_NAME_LEN 40
+
+struct net_dm_hw_entry {
+        char trap_name[NET_DM_MAX_HW_TRAP_NAME_LEN];
+        u32 count;
+};
+
+struct net_dm_hw_entries {
+        u32 num_entries;
+        struct net_dm_hw_entry entries[0];
+};
+
 struct per_cpu_dm_data {
-        spinlock_t              lock;   /* Protects 'skb' and 'send_timer' */
-        struct sk_buff          *skb;
+        spinlock_t              lock;   /* Protects 'skb', 'hw_entries' and
+                                         * 'send_timer'
+                                         */
+        union {
+                struct sk_buff                  *skb;
+                struct net_dm_hw_entries        *hw_entries;
+        };
         struct sk_buff_head     drop_queue;
         struct work_struct      dm_alert_work;
         struct timer_list       send_timer;
@@ -76,6 +95,7 @@ struct dm_hw_stat_delta {
 static struct genl_family net_drop_monitor_family;
 
 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
+static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_hw_cpu_data);
 
 static int dm_hit_limit = 64;
 static int dm_delay = 1;
@@ -92,10 +112,16 @@ struct net_dm_alert_ops {
         void (*napi_poll_probe)(void *ignore, struct napi_struct *napi,
                                 int work, int budget);
         void (*work_item_func)(struct work_struct *work);
+        void (*hw_work_item_func)(struct work_struct *work);
+        void (*hw_probe)(struct sk_buff *skb,
+                         const struct net_dm_hw_metadata *hw_metadata);
 };
 
 struct net_dm_skb_cb {
-        void *pc;
+        union {
+                struct net_dm_hw_metadata *hw_metadata;
+                void *pc;
+        };
 };
 
 #define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
@@ -266,10 +292,190 @@ static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
         rcu_read_unlock();
 }
 
+static struct net_dm_hw_entries *
+net_dm_hw_reset_per_cpu_data(struct per_cpu_dm_data *hw_data)
+{
+        struct net_dm_hw_entries *hw_entries;
+        unsigned long flags;
+
+        hw_entries = kzalloc(struct_size(hw_entries, entries, dm_hit_limit),
+                             GFP_KERNEL);
+        if (!hw_entries) {
+                /* If the memory allocation failed, we try to perform another
+                 * allocation in 1/10 second. Otherwise, the probe function
+                 * will constantly bail out.
+                 */
+                mod_timer(&hw_data->send_timer, jiffies + HZ / 10);
+        }
+
+        spin_lock_irqsave(&hw_data->lock, flags);
+        swap(hw_data->hw_entries, hw_entries);
+        spin_unlock_irqrestore(&hw_data->lock, flags);
+
+        return hw_entries;
+}
+
+static int net_dm_hw_entry_put(struct sk_buff *msg,
+                               const struct net_dm_hw_entry *hw_entry)
+{
+        struct nlattr *attr;
+
+        attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRY);
+        if (!attr)
+                return -EMSGSIZE;
+
+        if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME, hw_entry->trap_name))
+                goto nla_put_failure;
+
+        if (nla_put_u32(msg, NET_DM_ATTR_HW_TRAP_COUNT, hw_entry->count))
+                goto nla_put_failure;
+
+        nla_nest_end(msg, attr);
+
+        return 0;
+
+nla_put_failure:
+        nla_nest_cancel(msg, attr);
+        return -EMSGSIZE;
+}
+
+static int net_dm_hw_entries_put(struct sk_buff *msg,
+                                 const struct net_dm_hw_entries *hw_entries)
+{
+        struct nlattr *attr;
+        int i;
+
+        attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRIES);
+        if (!attr)
+                return -EMSGSIZE;
+
+        for (i = 0; i < hw_entries->num_entries; i++) {
+                int rc;
+
+                rc = net_dm_hw_entry_put(msg, &hw_entries->entries[i]);
+                if (rc)
+                        goto nla_put_failure;
+        }
+
+        nla_nest_end(msg, attr);
+
+        return 0;
+
+nla_put_failure:
+        nla_nest_cancel(msg, attr);
+        return -EMSGSIZE;
+}
+
+static int
+net_dm_hw_summary_report_fill(struct sk_buff *msg,
+                              const struct net_dm_hw_entries *hw_entries)
+{
+        struct net_dm_alert_msg anc_hdr = { 0 };
+        void *hdr;
+        int rc;
+
+        hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
+                          NET_DM_CMD_ALERT);
+        if (!hdr)
+                return -EMSGSIZE;
+
+        /* We need to put the ancillary header in order not to break user
+         * space.
+         */
+        if (nla_put(msg, NLA_UNSPEC, sizeof(anc_hdr), &anc_hdr))
+                goto nla_put_failure;
+
+        rc = net_dm_hw_entries_put(msg, hw_entries);
+        if (rc)
+                goto nla_put_failure;
+
+        genlmsg_end(msg, hdr);
+
+        return 0;
+
+nla_put_failure:
+        genlmsg_cancel(msg, hdr);
+        return -EMSGSIZE;
+}
+
+static void net_dm_hw_summary_work(struct work_struct *work)
+{
+        struct net_dm_hw_entries *hw_entries;
+        struct per_cpu_dm_data *hw_data;
+        struct sk_buff *msg;
+        int rc;
+
+        hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
+
+        hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
+        if (!hw_entries)
+                return;
+
+        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+        if (!msg)
+                goto out;
+
+        rc = net_dm_hw_summary_report_fill(msg, hw_entries);
+        if (rc) {
+                nlmsg_free(msg);
+                goto out;
+        }
+
+        genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
+
+out:
+        kfree(hw_entries);
+}
+
+static void
+net_dm_hw_summary_probe(struct sk_buff *skb,
+                        const struct net_dm_hw_metadata *hw_metadata)
+{
+        struct net_dm_hw_entries *hw_entries;
+        struct net_dm_hw_entry *hw_entry;
+        struct per_cpu_dm_data *hw_data;
+        unsigned long flags;
+        int i;
+
+        hw_data = this_cpu_ptr(&dm_hw_cpu_data);
+        spin_lock_irqsave(&hw_data->lock, flags);
+        hw_entries = hw_data->hw_entries;
+
+        if (!hw_entries)
+                goto out;
+
+        for (i = 0; i < hw_entries->num_entries; i++) {
+                hw_entry = &hw_entries->entries[i];
+                if (!strncmp(hw_entry->trap_name, hw_metadata->trap_name,
+                             NET_DM_MAX_HW_TRAP_NAME_LEN - 1)) {
+                        hw_entry->count++;
+                        goto out;
+                }
+        }
+        if (WARN_ON_ONCE(hw_entries->num_entries == dm_hit_limit))
+                goto out;
+
+        hw_entry = &hw_entries->entries[hw_entries->num_entries];
+        strlcpy(hw_entry->trap_name, hw_metadata->trap_name,
+                NET_DM_MAX_HW_TRAP_NAME_LEN - 1);
+        hw_entry->count = 1;
+        hw_entries->num_entries++;
+
+        if (!timer_pending(&hw_data->send_timer)) {
+                hw_data->send_timer.expires = jiffies + dm_delay * HZ;
+                add_timer(&hw_data->send_timer);
+        }
+
+out:
+        spin_unlock_irqrestore(&hw_data->lock, flags);
+}
+
 static const struct net_dm_alert_ops net_dm_alert_summary_ops = {
         .kfree_skb_probe        = trace_kfree_skb_hit,
         .napi_poll_probe        = trace_napi_poll_hit,
         .work_item_func         = send_dm_alert,
+        .hw_work_item_func      = net_dm_hw_summary_work,
+        .hw_probe               = net_dm_hw_summary_probe,
 };
 
 static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
@@ -323,7 +529,9 @@ static size_t net_dm_in_port_size(void)
                /* NET_DM_ATTR_IN_PORT nest */
         return nla_total_size(0) +
                /* NET_DM_ATTR_PORT_NETDEV_IFINDEX */
-               nla_total_size(sizeof(u32));
+               nla_total_size(sizeof(u32)) +
+               /* NET_DM_ATTR_PORT_NETDEV_NAME */
+               nla_total_size(IFNAMSIZ + 1);
 }
 
 #define NET_DM_MAX_SYMBOL_LEN 40
@@ -335,6 +543,8 @@ static size_t net_dm_packet_report_size(size_t payload_len)
         size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
 
         return NLMSG_ALIGN(size) +
+               /* NET_DM_ATTR_ORIGIN */
+               nla_total_size(sizeof(u16)) +
                /* NET_DM_ATTR_PC */
                nla_total_size(sizeof(u64)) +
                /* NET_DM_ATTR_SYMBOL */
@@ -351,7 +561,8 @@ static size_t net_dm_packet_report_size(size_t payload_len)
                nla_total_size(payload_len);
 }
 
-static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex)
+static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex,
+                                            const char *name)
 {
         struct nlattr *attr;
 
@@ -363,6 +574,9 @@ static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex)
             nla_put_u32(msg, NET_DM_ATTR_PORT_NETDEV_IFINDEX, ifindex))
                 goto nla_put_failure;
 
+        if (name && nla_put_string(msg, NET_DM_ATTR_PORT_NETDEV_NAME, name))
+                goto nla_put_failure;
+
         nla_nest_end(msg, attr);
 
         return 0;
@@ -387,6 +601,9 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
         if (!hdr)
                 return -EMSGSIZE;
 
+        if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
+                goto nla_put_failure;
+
         if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
                 goto nla_put_failure;
 
@@ -394,7 +611,7 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
         if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
                 goto nla_put_failure;
 
-        rc = net_dm_packet_report_in_port_put(msg, skb->skb_iif);
+        rc = net_dm_packet_report_in_port_put(msg, skb->skb_iif, NULL);
         if (rc)
                 goto nla_put_failure;
 
@@ -481,10 +698,250 @@ static void net_dm_packet_work(struct work_struct *work)
                 net_dm_packet_report(skb);
 }
 
+static size_t
+net_dm_hw_packet_report_size(size_t payload_len,
+                             const struct net_dm_hw_metadata *hw_metadata)
+{
+        size_t size;
+
+        size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
+
+        return NLMSG_ALIGN(size) +
+               /* NET_DM_ATTR_ORIGIN */
+               nla_total_size(sizeof(u16)) +
+               /* NET_DM_ATTR_HW_TRAP_GROUP_NAME */
+               nla_total_size(strlen(hw_metadata->trap_group_name) + 1) +
+               /* NET_DM_ATTR_HW_TRAP_NAME */
+               nla_total_size(strlen(hw_metadata->trap_name) + 1) +
+               /* NET_DM_ATTR_IN_PORT */
+               net_dm_in_port_size() +
+               /* NET_DM_ATTR_TIMESTAMP */
+               nla_total_size(sizeof(struct timespec)) +
+               /* NET_DM_ATTR_ORIG_LEN */
+               nla_total_size(sizeof(u32)) +
+               /* NET_DM_ATTR_PROTO */
+               nla_total_size(sizeof(u16)) +
+               /* NET_DM_ATTR_PAYLOAD */
+               nla_total_size(payload_len);
+}
+
+static int net_dm_hw_packet_report_fill(struct sk_buff *msg,
+                                        struct sk_buff *skb, size_t payload_len)
+{
+        struct net_dm_hw_metadata *hw_metadata;
+        struct nlattr *attr;
+        struct timespec ts;
+        void *hdr;
+
+        hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+
+        hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
+                          NET_DM_CMD_PACKET_ALERT);
+        if (!hdr)
+                return -EMSGSIZE;
+
+        if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_HW))
+                goto nla_put_failure;
+
+        if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_GROUP_NAME,
+                           hw_metadata->trap_group_name))
+                goto nla_put_failure;
+
+        if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME,
+                           hw_metadata->trap_name))
+                goto nla_put_failure;
+
+        if (hw_metadata->input_dev) {
+                struct net_device *dev = hw_metadata->input_dev;
+                int rc;
+
+                rc = net_dm_packet_report_in_port_put(msg, dev->ifindex,
+                                                      dev->name);
+                if (rc)
+                        goto nla_put_failure;
+        }
+
+        if (ktime_to_timespec_cond(skb->tstamp, &ts) &&
+            nla_put(msg, NET_DM_ATTR_TIMESTAMP, sizeof(ts), &ts))
+                goto nla_put_failure;
+
+        if (nla_put_u32(msg, NET_DM_ATTR_ORIG_LEN, skb->len))
+                goto nla_put_failure;
+
+        if (!payload_len)
+                goto out;
+
+        if (nla_put_u16(msg, NET_DM_ATTR_PROTO, be16_to_cpu(skb->protocol)))
+                goto nla_put_failure;
+
+        attr = skb_put(msg, nla_total_size(payload_len));
+        attr->nla_type = NET_DM_ATTR_PAYLOAD;
+        attr->nla_len = nla_attr_size(payload_len);
+        if (skb_copy_bits(skb, 0, nla_data(attr), payload_len))
+                goto nla_put_failure;
+
+out:
+        genlmsg_end(msg, hdr);
+
+        return 0;
+
+nla_put_failure:
+        genlmsg_cancel(msg, hdr);
+        return -EMSGSIZE;
+}
+
+static struct net_dm_hw_metadata *
+net_dm_hw_metadata_clone(const struct net_dm_hw_metadata *hw_metadata)
+{
+        struct net_dm_hw_metadata *n_hw_metadata;
+        const char *trap_group_name;
+        const char *trap_name;
+
+        n_hw_metadata = kmalloc(sizeof(*hw_metadata), GFP_ATOMIC);
+        if (!n_hw_metadata)
+                return NULL;
+
+        trap_group_name = kmemdup(hw_metadata->trap_group_name,
+                                  strlen(hw_metadata->trap_group_name) + 1,
+                                  GFP_ATOMIC | __GFP_ZERO);
+        if (!trap_group_name)
+                goto free_hw_metadata;
+        n_hw_metadata->trap_group_name = trap_group_name;
+
+        trap_name = kmemdup(hw_metadata->trap_name,
+                            strlen(hw_metadata->trap_name) + 1,
+                            GFP_ATOMIC | __GFP_ZERO);
+        if (!trap_name)
+                goto free_trap_group;
+        n_hw_metadata->trap_name = trap_name;
+
+        n_hw_metadata->input_dev = hw_metadata->input_dev;
+        if (n_hw_metadata->input_dev)
+                dev_hold(n_hw_metadata->input_dev);
+
+        return n_hw_metadata;
+
+free_trap_group:
+        kfree(trap_group_name);
+free_hw_metadata:
+        kfree(n_hw_metadata);
+        return NULL;
+}
+
+static void
+net_dm_hw_metadata_free(const struct net_dm_hw_metadata *hw_metadata)
+{
+        if (hw_metadata->input_dev)
+                dev_put(hw_metadata->input_dev);
+        kfree(hw_metadata->trap_name);
+        kfree(hw_metadata->trap_group_name);
+        kfree(hw_metadata);
+}
+
+static void net_dm_hw_packet_report(struct sk_buff *skb)
+{
+        struct net_dm_hw_metadata *hw_metadata;
+        struct sk_buff *msg;
+        size_t payload_len;
+        int rc;
+
+        if (skb->data > skb_mac_header(skb))
+                skb_push(skb, skb->data - skb_mac_header(skb));
+        else
+                skb_pull(skb, skb_mac_header(skb) - skb->data);
+
+        payload_len = min_t(size_t, skb->len, NET_DM_MAX_PACKET_SIZE);
+        if (net_dm_trunc_len)
+                payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
+
+        hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+        msg = nlmsg_new(net_dm_hw_packet_report_size(payload_len, hw_metadata),
+                        GFP_KERNEL);
+        if (!msg)
+                goto out;
+
+        rc = net_dm_hw_packet_report_fill(msg, skb, payload_len);
+        if (rc) {
+                nlmsg_free(msg);
+                goto out;
+        }
+
+        genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
+
+out:
+        net_dm_hw_metadata_free(NET_DM_SKB_CB(skb)->hw_metadata);
+        consume_skb(skb);
+}
+
+static void net_dm_hw_packet_work(struct work_struct *work)
+{
+        struct per_cpu_dm_data *hw_data;
+        struct sk_buff_head list;
+        struct sk_buff *skb;
+        unsigned long flags;
+
+        hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
+
+        __skb_queue_head_init(&list);
+
+        spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
+        skb_queue_splice_tail_init(&hw_data->drop_queue, &list);
+        spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+
+        while ((skb = __skb_dequeue(&list)))
+                net_dm_hw_packet_report(skb);
+}
+
+static void
+net_dm_hw_packet_probe(struct sk_buff *skb,
+                       const struct net_dm_hw_metadata *hw_metadata)
+{
+        struct net_dm_hw_metadata *n_hw_metadata;
+        ktime_t tstamp = ktime_get_real();
+        struct per_cpu_dm_data *hw_data;
+        struct sk_buff *nskb;
+        unsigned long flags;
+
+        nskb = skb_clone(skb, GFP_ATOMIC);
+        if (!nskb)
+                return;
+
+        n_hw_metadata = net_dm_hw_metadata_clone(hw_metadata);
+        if (!n_hw_metadata)
+                goto free;
+
+        NET_DM_SKB_CB(nskb)->hw_metadata = n_hw_metadata;
+        nskb->tstamp = tstamp;
+
+        hw_data = this_cpu_ptr(&dm_hw_cpu_data);
+
+        spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
+        if (skb_queue_len(&hw_data->drop_queue) < net_dm_queue_len)
+                __skb_queue_tail(&hw_data->drop_queue, nskb);
+        else
+                goto unlock_free;
+        spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+
+        schedule_work(&hw_data->dm_alert_work);
+
+        return;
+
+unlock_free:
+        spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
+        u64_stats_update_begin(&hw_data->stats.syncp);
+        hw_data->stats.dropped++;
+        u64_stats_update_end(&hw_data->stats.syncp);
+        net_dm_hw_metadata_free(n_hw_metadata);
+free:
+        consume_skb(nskb);
+}
+
 static const struct net_dm_alert_ops net_dm_alert_packet_ops = {
         .kfree_skb_probe        = net_dm_packet_trace_kfree_skb_hit,
         .napi_poll_probe        = net_dm_packet_trace_napi_poll_hit,
         .work_item_func         = net_dm_packet_work,
+        .hw_work_item_func      = net_dm_hw_packet_work,
+        .hw_probe               = net_dm_hw_packet_probe,
 };
 
 static const struct net_dm_alert_ops *net_dm_alert_ops_arr[] = {
@@ -492,6 +949,85 @@ static const struct net_dm_alert_ops *net_dm_alert_ops_arr[] = {
         [NET_DM_ALERT_MODE_PACKET]      = &net_dm_alert_packet_ops,
 };
 
+void net_dm_hw_report(struct sk_buff *skb,
+                      const struct net_dm_hw_metadata *hw_metadata)
+{
+        rcu_read_lock();
+
+        if (!monitor_hw)
+                goto out;
+
+        net_dm_alert_ops_arr[net_dm_alert_mode]->hw_probe(skb, hw_metadata);
+
+out:
+        rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(net_dm_hw_report);
+
+static int net_dm_hw_monitor_start(struct netlink_ext_ack *extack)
+{
+        const struct net_dm_alert_ops *ops;
+        int cpu;
+
+        if (monitor_hw) {
+                NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already enabled");
+                return -EAGAIN;
+        }
+
+        ops = net_dm_alert_ops_arr[net_dm_alert_mode];
+
+        if (!try_module_get(THIS_MODULE)) {
+                NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
+                return -ENODEV;
+        }
+
+        for_each_possible_cpu(cpu) {
+                struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+                struct net_dm_hw_entries *hw_entries;
+
+                INIT_WORK(&hw_data->dm_alert_work, ops->hw_work_item_func);
+                timer_setup(&hw_data->send_timer, sched_send_work, 0);
+                hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
+                kfree(hw_entries);
+        }
+
+        monitor_hw = true;
+
+        return 0;
+}
+
+static void net_dm_hw_monitor_stop(struct netlink_ext_ack *extack)
+{
+        int cpu;
+
+        if (!monitor_hw)
+                NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already disabled");
+
+        monitor_hw = false;
+
+        /* After this call returns we are guaranteed that no CPU is processing
+         * any hardware drops.
+         */
+        synchronize_rcu();
+
+        for_each_possible_cpu(cpu) {
+                struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+                struct sk_buff *skb;
+
+                del_timer_sync(&hw_data->send_timer);
+                cancel_work_sync(&hw_data->dm_alert_work);
+                while ((skb = __skb_dequeue(&hw_data->drop_queue))) {
+                        struct net_dm_hw_metadata *hw_metadata;
+
+                        hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
+                        net_dm_hw_metadata_free(hw_metadata);
+                        consume_skb(skb);
+                }
+        }
+
+        module_put(THIS_MODULE);
+}
+
 static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
 {
         const struct net_dm_alert_ops *ops;
@@ -604,6 +1140,11 @@ static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
         return rc;
 }
 
+static bool net_dm_is_monitoring(void)
+{
+        return trace_state == TRACE_ON || monitor_hw;
+}
+
 static int net_dm_alert_mode_get_from_info(struct genl_info *info,
                                            enum net_dm_alert_mode *p_alert_mode)
 {
@@ -665,8 +1206,8 @@ static int net_dm_cmd_config(struct sk_buff *skb,
         struct netlink_ext_ack *extack = info->extack;
         int rc;
 
-        if (trace_state == TRACE_ON) {
-                NL_SET_ERR_MSG_MOD(extack, "Cannot configure drop monitor while tracing is on");
+        if (net_dm_is_monitoring()) {
+                NL_SET_ERR_MSG_MOD(extack, "Cannot configure drop monitor during monitoring");
                 return -EBUSY;
         }
 
@@ -681,14 +1222,61 @@ static int net_dm_cmd_config(struct sk_buff *skb,
         return 0;
 }
 
+static int net_dm_monitor_start(bool set_sw, bool set_hw,
+                                struct netlink_ext_ack *extack)
+{
+        bool sw_set = false;
+        int rc;
+
+        if (set_sw) {
+                rc = set_all_monitor_traces(TRACE_ON, extack);
+                if (rc)
+                        return rc;
+                sw_set = true;
+        }
+
+        if (set_hw) {
+                rc = net_dm_hw_monitor_start(extack);
+                if (rc)
+                        goto err_monitor_hw;
+        }
+
+        return 0;
+
+err_monitor_hw:
+        if (sw_set)
+                set_all_monitor_traces(TRACE_OFF, extack);
+        return rc;
+}
+
+static void net_dm_monitor_stop(bool set_sw, bool set_hw,
+                                struct netlink_ext_ack *extack)
+{
+        if (set_hw)
+                net_dm_hw_monitor_stop(extack);
+        if (set_sw)
+                set_all_monitor_traces(TRACE_OFF, extack);
+}
+
 static int net_dm_cmd_trace(struct sk_buff *skb,
                         struct genl_info *info)
 {
+        bool set_sw = !!info->attrs[NET_DM_ATTR_SW_DROPS];
+        bool set_hw = !!info->attrs[NET_DM_ATTR_HW_DROPS];
+        struct netlink_ext_ack *extack = info->extack;
+
+        /* To maintain backward compatibility, we start / stop monitoring of
+         * software drops if no flag is specified.
+         */
+        if (!set_sw && !set_hw)
+                set_sw = true;
+
         switch (info->genlhdr->cmd) {
         case NET_DM_CMD_START:
-                return set_all_monitor_traces(TRACE_ON, info->extack);
+                return net_dm_monitor_start(set_sw, set_hw, extack);
         case NET_DM_CMD_STOP:
-                return set_all_monitor_traces(TRACE_OFF, info->extack);
+                net_dm_monitor_stop(set_sw, set_hw, extack);
+                return 0;
         }
 
         return -EOPNOTSUPP;
@@ -785,6 +1373,50 @@ nla_put_failure:
         return -EMSGSIZE;
 }
 
+static void net_dm_hw_stats_read(struct net_dm_stats *stats)
+{
+        int cpu;
+
+        memset(stats, 0, sizeof(*stats));
+        for_each_possible_cpu(cpu) {
+                struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+                struct net_dm_stats *cpu_stats = &hw_data->stats;
+                unsigned int start;
+                u64 dropped;
+
+                do {
+                        start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
+                        dropped = cpu_stats->dropped;
+                } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
+
+                stats->dropped += dropped;
+        }
+}
+
+static int net_dm_hw_stats_put(struct sk_buff *msg)
+{
+        struct net_dm_stats stats;
+        struct nlattr *attr;
+
+        net_dm_hw_stats_read(&stats);
+
+        attr = nla_nest_start(msg, NET_DM_ATTR_HW_STATS);
+        if (!attr)
+                return -EMSGSIZE;
+
+        if (nla_put_u64_64bit(msg, NET_DM_ATTR_STATS_DROPPED,
+                              stats.dropped, NET_DM_ATTR_PAD))
+                goto nla_put_failure;
+
+        nla_nest_end(msg, attr);
+
+        return 0;
+
+nla_put_failure:
+        nla_nest_cancel(msg, attr);
+        return -EMSGSIZE;
+}
+
 static int net_dm_stats_fill(struct sk_buff *msg, struct genl_info *info)
 {
         void *hdr;
@@ -799,6 +1431,10 @@ static int net_dm_stats_fill(struct sk_buff *msg, struct genl_info *info)
         if (rc)
                 goto nla_put_failure;
 
+        rc = net_dm_hw_stats_put(msg);
+        if (rc)
+                goto nla_put_failure;
+
         genlmsg_end(msg, hdr);
 
         return 0;
@@ -872,6 +1508,8 @@ static const struct nla_policy net_dm_nl_policy[NET_DM_ATTR_MAX + 1] = {
         [NET_DM_ATTR_ALERT_MODE] = { .type = NLA_U8 },
         [NET_DM_ATTR_TRUNC_LEN] = { .type = NLA_U32 },
         [NET_DM_ATTR_QUEUE_LEN] = { .type = NLA_U32 },
+        [NET_DM_ATTR_SW_DROPS]  = {. type = NLA_FLAG },
+        [NET_DM_ATTR_HW_DROPS]  = {. type = NLA_FLAG },
 };
 
 static const struct genl_ops dropmon_ops[] = {
@@ -934,9 +1572,57 @@ static struct notifier_block dropmon_net_notifier = {
         .notifier_call = dropmon_net_event
 };
 
-static int __init init_net_drop_monitor(void)
+static void __net_dm_cpu_data_init(struct per_cpu_dm_data *data)
+{
+        spin_lock_init(&data->lock);
+        skb_queue_head_init(&data->drop_queue);
+        u64_stats_init(&data->stats.syncp);
+}
+
+static void __net_dm_cpu_data_fini(struct per_cpu_dm_data *data)
+{
+        WARN_ON(!skb_queue_empty(&data->drop_queue));
+}
+
+static void net_dm_cpu_data_init(int cpu)
 {
         struct per_cpu_dm_data *data;
+
+        data = &per_cpu(dm_cpu_data, cpu);
+        __net_dm_cpu_data_init(data);
+}
+
+static void net_dm_cpu_data_fini(int cpu)
+{
+        struct per_cpu_dm_data *data;
+
+        data = &per_cpu(dm_cpu_data, cpu);
+        /* At this point, we should have exclusive access
+         * to this struct and can free the skb inside it.
+         */
+        consume_skb(data->skb);
+        __net_dm_cpu_data_fini(data);
+}
+
+static void net_dm_hw_cpu_data_init(int cpu)
+{
+        struct per_cpu_dm_data *hw_data;
+
+        hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+        __net_dm_cpu_data_init(hw_data);
+}
+
+static void net_dm_hw_cpu_data_fini(int cpu)
+{
+        struct per_cpu_dm_data *hw_data;
+
+        hw_data = &per_cpu(dm_hw_cpu_data, cpu);
+        kfree(hw_data->hw_entries);
+        __net_dm_cpu_data_fini(hw_data);
+}
+
+static int __init init_net_drop_monitor(void)
+{
         int cpu, rc;
 
         pr_info("Initializing network drop monitor service\n");
@@ -962,10 +1648,8 @@ static int __init init_net_drop_monitor(void)
         rc = 0;
 
         for_each_possible_cpu(cpu) {
-                data = &per_cpu(dm_cpu_data, cpu);
-                spin_lock_init(&data->lock);
-                skb_queue_head_init(&data->drop_queue);
-                u64_stats_init(&data->stats.syncp);
+                net_dm_cpu_data_init(cpu);
+                net_dm_hw_cpu_data_init(cpu);
         }
 
         goto out;
@@ -978,7 +1662,6 @@ out:
 
 static void exit_net_drop_monitor(void)
 {
-        struct per_cpu_dm_data *data;
         int cpu;
 
         BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
@@ -989,13 +1672,8 @@ static void exit_net_drop_monitor(void)
          */
 
         for_each_possible_cpu(cpu) {
-                data = &per_cpu(dm_cpu_data, cpu);
-                /*
-                 * At this point, we should have exclusive access
-                 * to this struct and can free the skb inside it
-                 */
-                kfree_skb(data->skb);
-                WARN_ON(!skb_queue_empty(&data->drop_queue));
+                net_dm_hw_cpu_data_fini(cpu);
+                net_dm_cpu_data_fini(cpu);
         }
 
         BUG_ON(genl_unregister_family(&net_drop_monitor_family));