lguest: the guest code
lguest is a simple hypervisor for Linux on Linux. Unlike kvm it doesn't need
VT/SVM hardware. Unlike Xen it's simply "modprobe and go". Unlike both, it's
5000 lines and self-contained.
Performance is ok, but not great (-30% on kernel compile). But given its
hackability, I expect this to improve, along with the paravirt_ops code which
it supplies a complete example for. There's also a 64-bit version being
worked on and other craziness.
But most of all, lguest is awesome fun! Too much of the kernel is a big ball
of hair. lguest is simple enough to dive into and hack, plus has some warts
which scream "fork me!".
This patch:
This is the code and headers required to make an i386 kernel an lguest guest.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/lguest/lguest_bus.c b/drivers/lguest/lguest_bus.c
new file mode 100644
index 0000000..18d6ab2
--- /dev/null
+++ b/drivers/lguest/lguest_bus.c
@@ -0,0 +1,148 @@
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/lguest_bus.h>
+#include <asm/io.h>
+
+static ssize_t type_show(struct device *_dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ return sprintf(buf, "%hu", lguest_devices[dev->index].type);
+}
+static ssize_t features_show(struct device *_dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ return sprintf(buf, "%hx", lguest_devices[dev->index].features);
+}
+static ssize_t pfn_show(struct device *_dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ return sprintf(buf, "%u", lguest_devices[dev->index].pfn);
+}
+static ssize_t status_show(struct device *_dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ return sprintf(buf, "%hx", lguest_devices[dev->index].status);
+}
+static ssize_t status_store(struct device *_dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ if (sscanf(buf, "%hi", &lguest_devices[dev->index].status) != 1)
+ return -EINVAL;
+ return count;
+}
+static struct device_attribute lguest_dev_attrs[] = {
+ __ATTR_RO(type),
+ __ATTR_RO(features),
+ __ATTR_RO(pfn),
+ __ATTR(status, 0644, status_show, status_store),
+ __ATTR_NULL
+};
+
+static int lguest_dev_match(struct device *_dev, struct device_driver *_drv)
+{
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ struct lguest_driver *drv = container_of(_drv,struct lguest_driver,drv);
+
+ return (drv->device_type == lguest_devices[dev->index].type);
+}
+
+struct lguest_bus {
+ struct bus_type bus;
+ struct device dev;
+};
+
+static struct lguest_bus lguest_bus = {
+ .bus = {
+ .name = "lguest",
+ .match = lguest_dev_match,
+ .dev_attrs = lguest_dev_attrs,
+ },
+ .dev = {
+ .parent = NULL,
+ .bus_id = "lguest",
+ }
+};
+
+static int lguest_dev_probe(struct device *_dev)
+{
+ int ret;
+ struct lguest_device *dev = container_of(_dev,struct lguest_device,dev);
+ struct lguest_driver *drv = container_of(dev->dev.driver,
+ struct lguest_driver, drv);
+
+ lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER;
+ ret = drv->probe(dev);
+ if (ret == 0)
+ lguest_devices[dev->index].status |= LGUEST_DEVICE_S_DRIVER_OK;
+ return ret;
+}
+
+int register_lguest_driver(struct lguest_driver *drv)
+{
+ if (!lguest_devices)
+ return 0;
+
+ drv->drv.bus = &lguest_bus.bus;
+ drv->drv.name = drv->name;
+ drv->drv.owner = drv->owner;
+ drv->drv.probe = lguest_dev_probe;
+
+ return driver_register(&drv->drv);
+}
+EXPORT_SYMBOL_GPL(register_lguest_driver);
+
+static void add_lguest_device(unsigned int index)
+{
+ struct lguest_device *new;
+
+ lguest_devices[index].status |= LGUEST_DEVICE_S_ACKNOWLEDGE;
+ new = kmalloc(sizeof(struct lguest_device), GFP_KERNEL);
+ if (!new) {
+ printk(KERN_EMERG "Cannot allocate lguest device %u\n", index);
+ lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
+ return;
+ }
+
+ new->index = index;
+ new->private = NULL;
+ memset(&new->dev, 0, sizeof(new->dev));
+ new->dev.parent = &lguest_bus.dev;
+ new->dev.bus = &lguest_bus.bus;
+ sprintf(new->dev.bus_id, "%u", index);
+ if (device_register(&new->dev) != 0) {
+ printk(KERN_EMERG "Cannot register lguest device %u\n", index);
+ lguest_devices[index].status |= LGUEST_DEVICE_S_FAILED;
+ kfree(new);
+ }
+}
+
+static void scan_devices(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < LGUEST_MAX_DEVICES; i++)
+ if (lguest_devices[i].type)
+ add_lguest_device(i);
+}
+
+static int __init lguest_bus_init(void)
+{
+ if (strcmp(paravirt_ops.name, "lguest") != 0)
+ return 0;
+
+ /* Devices are in page above top of "normal" mem. */
+ lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
+
+ if (bus_register(&lguest_bus.bus) != 0
+ || device_register(&lguest_bus.dev) != 0)
+ panic("lguest bus registration failed");
+
+ scan_devices();
+ return 0;
+}
+postcore_initcall(lguest_bus_init);