Signed-off-by: Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>
---
drivers/virtio/Kconfig | 6 +
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio_cpu.c | 226 +++++++++++++++++++++++++++++++++++++++++++
drivers/virtio/virtio_pci.c | 1 +
kernel/cpu.c | 2 +
5 files changed, 236 insertions(+), 0 deletions(-)
create mode 100644 drivers/virtio/virtio_cpu.c
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 73a414c..6665d4d 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -23,3 +23,9 @@ config VIRTIO_PCI
If unsure, say M.
+config VIRTIO_CPU
+ tristate "virtio-cpu"
+ depends on VIRTIO_PCI && EXPERIMENTAL
+ ---help---
+ I'll obviously put a better description later
+
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index cc84999..057ebcc 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_VIRTIO) += virtio.o
obj-$(CONFIG_VIRTIO_RING) += virtio_ring.o
obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
+obj-$(CONFIG_VIRTIO_CPU) += virtio_cpu.o
diff --git a/drivers/virtio/virtio_cpu.c b/drivers/virtio/virtio_cpu.c
new file mode 100644
index 0000000..8dc0c7d
--- /dev/null
+++ b/drivers/virtio/virtio_cpu.c
@@ -0,0 +1,226 @@
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+
+#include <linux/cpu.h>
+#include <linux/kthread.h>
+#include <linux/wait.h>
+#include <linux/freezer.h>
+
+#define VIRTIO_ID_CPU 4
+
+#define CMD_CPU_SET 1
+
+struct virtio_hotplug_hdr {
+ u8 cmd;
+ u8 status;
+};
+
+struct hotplug_buf {
+ struct virtio_hotplug_hdr hdr;
+ u32 arg;
+};
+
+struct virtio_hotplug {
+ struct virtio_device *dev;
+ struct virtqueue *cmd_receive;
+ struct task_struct *hotplug_thread;
+ wait_queue_head_t hotplug_wait;
+ u32 hotplug_target;
+ int thread_started;
+};
+
+
+static struct virtio_device_id id_table[] = {
+ { VIRTIO_ID_CPU, VIRTIO_DEV_ANY_ID},
+ { 0 },
+};
+
+void *__alloc_virtio_buf(int size)
+{
+ return kzalloc(size, GFP_KERNEL);
+}
+
+#define alloc_hotplug_buf() (__alloc_virtio_buf(sizeof(struct hotplug_buf)))
+
+static int __send_hotplug_buf(u8 cmd, struct hotplug_buf *buf,
+ struct virtqueue *vq)
+{
+ struct scatterlist sg[2];
+ int err = 0;
+
+ sg_init_table(sg, 2);
+
+ sg_set_buf(&sg[0], &buf->hdr, sizeof(buf->hdr));
+ sg_set_buf(&sg[1], &buf->arg, sizeof(buf->arg));
+
+ err = vq->vq_ops->add_buf(vq, sg, 0, 2, buf);
+ if (err)
+ return err;
+
+ vq->vq_ops->kick(vq);
+
+ return 0;
+}
+
+/* Prepare the virtio driver to receive a command. */
+static int prepare_to_receive(struct virtio_hotplug *v)
+{
+ void *buf = alloc_hotplug_buf();
+
+ if (!buf)
+ return -ENOMEM;
+
+ return __send_hotplug_buf(0, buf, v->cmd_receive);
+}
+
+static void hotplug_add_cpus(struct virtio_hotplug *v)
+{
+ struct sys_device *dev;
+ struct virtqueue *vq = v->cmd_receive;
+ struct hotplug_buf *buf;
+ int i, len;
+ int err;
+
+ while ((buf = vq->vq_ops->get_buf(vq, &len)) != NULL) {
+ switch (buf->hdr.cmd) {
+ case CMD_CPU_SET:
+ v->hotplug_target = buf->arg;
+
+ if (v->hotplug_target > num_present_cpus())
+ v->hotplug_target = num_present_cpus();
+ break;
+ default:
+ printk("%s: Unrecognized command %d\n",
+ __func__, buf->hdr.cmd);
+ break;
+ }
+ }
+ kfree(buf);
+
+
+ while ((i = num_online_cpus()) < v->hotplug_target) {
+ err = cpu_up(i);
+ dev = get_cpu_sysdev(i);
+ if (!err) {
+ if (dev)
+ kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+ }
+ }
+
+ while ((i = num_online_cpus()) > v->hotplug_target) {
+ i--;
+ dev = get_cpu_sysdev(i);
+ err = cpu_down(i);
+ if (!err) {
+ if (dev)
+ kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+ }
+ }
+}
+
+static int virtio_do_hotplug(void *p)
+{
+ struct virtio_hotplug *v = p;
+ DEFINE_WAIT(wait);
+ set_freezable();
+
+ for (;;) {
+ prepare_to_receive(v);
+ prepare_to_wait(&v->hotplug_wait, &wait, TASK_UNINTERRUPTIBLE);
+ v->thread_started = 1;
+ schedule();
+ finish_wait(&v->hotplug_wait, &wait);
+
+ try_to_freeze();
+
+ if (kthread_should_stop())
+ break;
+
+ hotplug_add_cpus(v);
+ v->hotplug_target = 0;
+ }
+ return 0;
+}
+
+/* We need a separate thread because cpu_up() and cpu_down() cannot
+ * be called in interrupt context */
+static bool hotplug_get_cmd(struct virtqueue *vq)
+{
+ struct virtio_hotplug *v = vq->vdev->priv;
+
+ wake_up(&v->hotplug_wait);
+ return true;
+
+}
+
+static int virtio_cpu_probe(struct virtio_device *vdev)
+{
+ int err;
+ struct virtio_hotplug *v;
+
+ v = kzalloc(sizeof(*v), GFP_KERNEL);
+ if (!v)
+ return -ENOMEM;
+
+
+ if (IS_ERR(v->cmd_receive)) {
+ printk("%s: Couldn't find cmd_receive queue\n", __func__);
+ return PTR_ERR(v->cmd_receive);
+ }
+
+ vdev->priv = v;
+
+ init_waitqueue_head(&v->hotplug_wait);
+
+ v->thread_started = 0;
+ v->hotplug_thread = kthread_run(virtio_do_hotplug, v,
+ "virtio_hotplugd\n");
+
+ if (IS_ERR(v->hotplug_thread)) {
+ err = PTR_ERR(v->hotplug_thread);
+ goto out;
+ }
+
+ v->cmd_receive = vdev->config->find_vq(vdev, 0, hotplug_get_cmd);
+
+ printk("Registered virtio hotplug driver\n");
+ return 0;
+out:
+ vdev->config->del_vq(v->cmd_receive);
+ return err;
+}
+
+static void virtio_cpu_remove(struct virtio_device *vdev)
+{
+ struct virtio_hotplug *v = vdev->priv;
+ kthread_stop(v->hotplug_thread);
+ vdev->config->del_vq(v->cmd_receive);
+ kfree(v);
+}
+
+
+static struct virtio_driver virtio_cpu = {
+ .driver.name = KBUILD_MODNAME,
+ .driver.owner = THIS_MODULE,
+ .id_table = id_table,
+ .probe = virtio_cpu_probe,
+ .remove = __devexit_p(virtio_cpu_remove),
+};
+
+static int __init virtio_cpu_init(void)
+{
+ return register_virtio_driver(&virtio_cpu);
+}
+
+static void __exit virtio_cpu_exit(void)
+{
+ unregister_virtio_driver(&virtio_cpu);
+}
+
+module_init(virtio_cpu_init);
+module_exit(virtio_cpu_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Glauber de Oliveira Costa");
+MODULE_DESCRIPTION("virtio driver for cpu hotplugging");
+MODULE_VERSION("1");
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index e1fa68d..8d5a719 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -67,6 +67,7 @@ static struct pci_device_id virtio_pci_id_table[] = {
{ 0x1AF4, 0x1000, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
{ 0x1AF4, 0x1001, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
{ 0x1AF4, 0x1002, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
+ { 0x2523, 0x2325, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* cpu hotplug driver */
{ 0 },
};
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6b3a0c1..c432c28 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -219,6 +219,7 @@ int cpu_down(unsigned int cpu)
mutex_unlock(&cpu_add_remove_lock);
return err;
}
+EXPORT_SYMBOL_GPL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/
/* Requires cpu_add_remove_lock to be held */
@@ -284,6 +285,7 @@ int __cpuinit cpu_up(unsigned int cpu)
mutex_unlock(&cpu_add_remove_lock);
return err;
}
+EXPORT_SYMBOL_GPL(cpu_up);
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_t frozen_cpus;
--
1.5.0.6
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