virtio_scsi: use virtio IRQ affinity

Use automatic IRQ affinity assignment in the virtio layer if available,
and build the blk-mq queues based on it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 12 insertions, 115 deletions

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index c9c5ea0611e9..939c47df73fa 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/mempool.h>
+#include <linux/interrupt.h>
 #include <linux/virtio.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_config.h>
@@ -29,6 +30,7 @@
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_tcq.h>
 #include <linux/seqlock.h>
+#include <linux/blk-mq-virtio.h>
 
 #define VIRTIO_SCSI_MEMPOOL_SZ 64
 #define VIRTIO_SCSI_EVENT_LEN 8
@@ -108,7 +110,6 @@ struct virtio_scsi {
         bool affinity_hint_set;
 
         struct hlist_node node;
-        struct hlist_node node_dead;
 
         /* Protected by event_vq lock */
         bool stop_events;
@@ -118,7 +119,6 @@ struct virtio_scsi {
         struct virtio_scsi_vq req_vqs[];
 };
 
-static enum cpuhp_state virtioscsi_online;
 static struct kmem_cache *virtscsi_cmd_cache;
 static mempool_t *virtscsi_cmd_pool;
 
@@ -766,6 +766,13 @@ static void virtscsi_target_destroy(struct scsi_target *starget)
         kfree(tgt);
 }
 
+static int virtscsi_map_queues(struct Scsi_Host *shost)
+{
+        struct virtio_scsi *vscsi = shost_priv(shost);
+
+        return blk_mq_virtio_map_queues(&shost->tag_set, vscsi->vdev, 2);
+}
+
 static struct scsi_host_template virtscsi_host_template_single = {
         .module = THIS_MODULE,
         .name = "Virtio SCSI HBA",
@@ -801,6 +808,7 @@ static struct scsi_host_template virtscsi_host_template_multi = {
         .use_clustering = ENABLE_CLUSTERING,
         .target_alloc = virtscsi_target_alloc,
         .target_destroy = virtscsi_target_destroy,
+        .map_queues = virtscsi_map_queues,
         .track_queue_depth = 1,
 };
 
@@ -817,80 +825,6 @@ static struct scsi_host_template virtscsi_host_template_multi = {
                 virtio_cwrite(vdev, struct virtio_scsi_config, fld, &__val); \
         } while(0)
 
-static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
-{
-        int i;
-        int cpu;
-
-        /* In multiqueue mode, when the number of cpu is equal
-         * to the number of request queues, we let the qeueues
-         * to be private to one cpu by setting the affinity hint
-         * to eliminate the contention.
-         */
-        if ((vscsi->num_queues == 1 ||
-             vscsi->num_queues != num_online_cpus()) && affinity) {
-                if (vscsi->affinity_hint_set)
-                        affinity = false;
-                else
-                        return;
-        }
-
-        if (affinity) {
-                i = 0;
-                for_each_online_cpu(cpu) {
-                        virtqueue_set_affinity(vscsi->req_vqs[i].vq, cpu);
-                        i++;
-                }
-
-                vscsi->affinity_hint_set = true;
-        } else {
-                for (i = 0; i < vscsi->num_queues; i++) {
-                        if (!vscsi->req_vqs[i].vq)
-                                continue;
-
-                        virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
-                }
-
-                vscsi->affinity_hint_set = false;
-        }
-}
-
-static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
-{
-        get_online_cpus();
-        __virtscsi_set_affinity(vscsi, affinity);
-        put_online_cpus();
-}
-
-static int virtscsi_cpu_online(unsigned int cpu, struct hlist_node *node)
-{
-        struct virtio_scsi *vscsi = hlist_entry_safe(node, struct virtio_scsi,
-                                                     node);
-        __virtscsi_set_affinity(vscsi, true);
-        return 0;
-}
-
-static int virtscsi_cpu_notif_add(struct virtio_scsi *vi)
-{
-        int ret;
-
-        ret = cpuhp_state_add_instance(virtioscsi_online, &vi->node);
-        if (ret)
-                return ret;
-
-        ret = cpuhp_state_add_instance(CPUHP_VIRT_SCSI_DEAD, &vi->node_dead);
-        if (ret)
-                cpuhp_state_remove_instance(virtioscsi_online, &vi->node);
-        return ret;
-}
-
-static void virtscsi_cpu_notif_remove(struct virtio_scsi *vi)
-{
-        cpuhp_state_remove_instance_nocalls(virtioscsi_online, &vi->node);
-        cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_SCSI_DEAD,
-                                            &vi->node_dead);
-}
-
 static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
                              struct virtqueue *vq)
 {
@@ -900,14 +834,8 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq,
 
 static void virtscsi_remove_vqs(struct virtio_device *vdev)
 {
-        struct Scsi_Host *sh = virtio_scsi_host(vdev);
-        struct virtio_scsi *vscsi = shost_priv(sh);
-
-        virtscsi_set_affinity(vscsi, false);
-
         /* Stop all the virtqueues. */
         vdev->config->reset(vdev);
-
         vdev->config->del_vqs(vdev);
 }
 
@@ -920,6 +848,7 @@ static int virtscsi_init(struct virtio_device *vdev,
         vq_callback_t **callbacks;
         const char **names;
         struct virtqueue **vqs;
+        struct irq_affinity desc = { .pre_vectors = 2 };
 
         num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE;
         vqs = kmalloc(num_vqs * sizeof(struct virtqueue *), GFP_KERNEL);
@@ -942,7 +871,7 @@ static int virtscsi_init(struct virtio_device *vdev,
 
         /* Discover virtqueues and write information to configuration.  */
         err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names,
-                        NULL);
+                        &desc);
         if (err)
                 goto out;
 
@@ -1008,10 +937,6 @@ static int virtscsi_probe(struct virtio_device *vdev)
         if (err)
                 goto virtscsi_init_failed;
 
-        err = virtscsi_cpu_notif_add(vscsi);
-        if (err)
-                goto scsi_add_host_failed;
-
         cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
         shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
         shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;
@@ -1066,9 +991,6 @@ static void virtscsi_remove(struct virtio_device *vdev)
                 virtscsi_cancel_event_work(vscsi);
 
         scsi_remove_host(shost);
-
-        virtscsi_cpu_notif_remove(vscsi);
-
         virtscsi_remove_vqs(vdev);
         scsi_host_put(shost);
 }
@@ -1076,10 +998,6 @@ static void virtscsi_remove(struct virtio_device *vdev)
 #ifdef CONFIG_PM_SLEEP
 static int virtscsi_freeze(struct virtio_device *vdev)
 {
-        struct Scsi_Host *sh = virtio_scsi_host(vdev);
-        struct virtio_scsi *vscsi = shost_priv(sh);
-
-        virtscsi_cpu_notif_remove(vscsi);
         virtscsi_remove_vqs(vdev);
         return 0;
 }
@@ -1094,11 +1012,6 @@ static int virtscsi_restore(struct virtio_device *vdev)
         if (err)
                 return err;
 
-        err = virtscsi_cpu_notif_add(vscsi);
-        if (err) {
-                vdev->config->del_vqs(vdev);
-                return err;
-        }
         virtio_device_ready(vdev);
 
         if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG))
@@ -1153,16 +1066,6 @@ static int __init init(void)
                 pr_err("mempool_create() for virtscsi_cmd_pool failed\n");
                 goto error;
         }
-        ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
-                                      "scsi/virtio:online",
-                                      virtscsi_cpu_online, NULL);
-        if (ret < 0)
-                goto error;
-        virtioscsi_online = ret;
-        ret = cpuhp_setup_state_multi(CPUHP_VIRT_SCSI_DEAD, "scsi/virtio:dead",
-                                      NULL, virtscsi_cpu_online);
-        if (ret)
-                goto error;
         ret = register_virtio_driver(&virtio_scsi_driver);
         if (ret < 0)
                 goto error;
@@ -1178,17 +1081,12 @@ error:
                 kmem_cache_destroy(virtscsi_cmd_cache);
                 virtscsi_cmd_cache = NULL;
         }
-        if (virtioscsi_online)
-                cpuhp_remove_multi_state(virtioscsi_online);
-        cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
         return ret;
 }
 
 static void __exit fini(void)
 {
         unregister_virtio_driver(&virtio_scsi_driver);
-        cpuhp_remove_multi_state(virtioscsi_online);
-        cpuhp_remove_multi_state(CPUHP_VIRT_SCSI_DEAD);
         mempool_destroy(virtscsi_cmd_pool);
         kmem_cache_destroy(virtscsi_cmd_cache);
 }
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 921acaaa1601..01aea80a503e 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -26,7 +26,6 @@ enum cpuhp_state {
         CPUHP_ARM_OMAP_WAKE_DEAD,
         CPUHP_IRQ_POLL_DEAD,
         CPUHP_BLOCK_SOFTIRQ_DEAD,
-        CPUHP_VIRT_SCSI_DEAD,
         CPUHP_ACPI_CPUDRV_DEAD,
         CPUHP_S390_PFAULT_DEAD,
         CPUHP_BLK_MQ_DEAD,