kvm tools: Use ioeventfd in virtio-blk

Use ioeventfds to receive notifications of IO events in virtio-blk.
Doing so prevents an exit every time we read/write from/to the
virtio disk.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c
index a8f9d8c9c88593d7dacf0b1ac44c315936415f6f..8d54f5a04879cd4ab1e5c2b15d48ac0fac2e73e9 100644 (file)
--- a/tools/kvm/virtio/blk.c
+++ b/tools/kvm/virtio/blk.c
@@ -10,6 +10,7 @@
 #include "kvm/kvm.h"
 #include "kvm/pci.h"
 #include "kvm/threadpool.h"
+#include "kvm/ioeventfd.h"
 
 #include <linux/virtio_ring.h>
 #include <linux/virtio_blk.h>
@@ -243,11 +244,19 @@ static struct ioport_operations virtio_blk_io_ops = {
        .io_out = virtio_blk_pci_io_out,
 };
 
+static void ioevent_callback(struct kvm *kvm, void *param)
+{
+       struct blk_dev_job *job = param;
+
+       thread_pool__do_job(job->job_id);
+}
+
 void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
 {
        u16 blk_dev_base_addr;
-       u8 dev, pin, line;
+       u8 dev, pin, line, i;
        struct blk_dev *bdev;
+       struct ioevent ioevent;
 
        if (!disk)
                return;
@@ -293,6 +302,20 @@ void virtio_blk__init(struct kvm *kvm, struct disk_image *disk)
        bdev->pci_hdr.irq_line  = line;
 
        pci__register(&bdev->pci_hdr, dev);
+
+       for (i = 0; i < NUM_VIRT_QUEUES; i++) {
+               ioevent = (struct ioevent) {
+                       .io_addr                = blk_dev_base_addr + VIRTIO_PCI_QUEUE_NOTIFY,
+                       .io_len                 = sizeof(u16),
+                       .fn                     = ioevent_callback,
+                       .datamatch              = i,
+                       .fn_ptr                 = &bdev->jobs[i],
+                       .fn_kvm                 = kvm,
+                       .fd                     = eventfd(0, 0),
+               };
+
+               ioeventfd__add_event(&ioevent);
+       }
 }
 
 void virtio_blk__init_all(struct kvm *kvm)
@@ -309,6 +332,7 @@ void virtio_blk__delete_all(struct kvm *kvm)
                struct blk_dev *bdev;
 
                bdev = list_first_entry(&bdevs, struct blk_dev, list);
+               ioeventfd__del_event(bdev->base_addr + VIRTIO_PCI_QUEUE_NOTIFY, 0);
                list_del(&bdev->list);
                free(bdev);
        }