-/*P:050 Lguest guests use a very simple method to describe devices. It's a
- * series of device descriptors contained just above the top of normal
+/*P:050
+ * Lguest guests use a very simple method to describe devices. It's a
+ * series of device descriptors contained just above the top of normal Guest
* memory.
*
* We use the standard "virtio" device infrastructure, which provides us with a
* console, a network and a block driver. Each one expects some configuration
- * information and a "virtqueue" mechanism to send and receive data. :*/
+ * information and a "virtqueue" or two to send and receive data.
+:*/
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/lguest_launcher.h>
/* The pointer to our (page) of device descriptions. */
static void *lguest_devices;
-/* Unique numbering for lguest devices. */
-static unsigned int dev_index;
-
-/* For Guests, device memory can be used as normal memory, so we cast away the
- * __iomem to quieten sparse. */
+/*
+ * For Guests, device memory can be used as normal memory, so we cast away the
+ * __iomem to quieten sparse.
+ */
static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
{
- return (__force void *)ioremap(phys_addr, PAGE_SIZE*pages);
+ return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);
}
static inline void lguest_unmap(void *addr)
iounmap((__force void __iomem *)addr);
}
-/*D:100 Each lguest device is just a virtio device plus a pointer to its entry
- * in the lguest_devices page. */
+/*D:100
+ * Each lguest device is just a virtio device plus a pointer to its entry
+ * in the lguest_devices page.
+ */
struct lguest_device {
struct virtio_device vdev;
struct lguest_device_desc *desc;
};
-/* Since the virtio infrastructure hands us a pointer to the virtio_device all
+/*
+ * Since the virtio infrastructure hands us a pointer to the virtio_device all
* the time, it helps to have a curt macro to get a pointer to the struct
- * lguest_device it's enclosed in. */
-#define to_lgdev(vdev) container_of(vdev, struct lguest_device, vdev)
+ * lguest_device it's enclosed in.
+ */
+#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
/*D:130
* Device configurations
*
- * The configuration information for a device consists of a series of fields.
- * The device will look for these fields during setup.
- *
- * For us these fields come immediately after that device's descriptor in the
- * lguest_devices page.
+ * The configuration information for a device consists of one or more
+ * virtqueues, a feature bitmap, and some configuration bytes. The
+ * configuration bytes don't really matter to us: the Launcher sets them up, and
+ * the driver will look at them during setup.
*
- * Each field starts with a "type" byte, a "length" byte, then that number of
- * bytes of configuration information. The device descriptor tells us the
- * total configuration length so we know when we've reached the last field. */
+ * A convenient routine to return the device's virtqueue config array:
+ * immediately after the descriptor.
+ */
+static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
+{
+ return (void *)(desc + 1);
+}
+
+/* The features come immediately after the virtqueues. */
+static u8 *lg_features(const struct lguest_device_desc *desc)
+{
+ return (void *)(lg_vq(desc) + desc->num_vq);
+}
+
+/* The config space comes after the two feature bitmasks. */
+static u8 *lg_config(const struct lguest_device_desc *desc)
+{
+ return lg_features(desc) + desc->feature_len * 2;
+}
-/* type + length bytes */
-#define FHDR_LEN 2
+/* The total size of the config page used by this device (incl. desc) */
+static unsigned desc_size(const struct lguest_device_desc *desc)
+{
+ return sizeof(*desc)
+ + desc->num_vq * sizeof(struct lguest_vqconfig)
+ + desc->feature_len * 2
+ + desc->config_len;
+}
-/* This finds the first field of a given type for a device's configuration. */
-static void *lg_find(struct virtio_device *vdev, u8 type, unsigned int *len)
+/* This gets the device's feature bits. */
+static u32 lg_get_features(struct virtio_device *vdev)
{
+ unsigned int i;
+ u32 features = 0;
struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
- int i;
+ u8 *in_features = lg_features(desc);
- for (i = 0; i < desc->config_len; i += FHDR_LEN + desc->config[i+1]) {
- if (desc->config[i] == type) {
- /* Mark it used, so Host can know we looked at it, and
- * also so we won't find the same one twice. */
- desc->config[i] |= 0x80;
- /* Remember, the second byte is the length. */
- *len = desc->config[i+1];
- /* We return a pointer to the field header. */
- return desc->config + i;
- }
- }
+ /* We do this the slow but generic way. */
+ for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+ if (in_features[i / 8] & (1 << (i % 8)))
+ features |= (1 << i);
- /* Not found: return NULL for failure. */
- return NULL;
+ return features;
+}
+
+/*
+ * The virtio core takes the features the Host offers, and copies the ones
+ * supported by the driver into the vdev->features array. Once that's all
+ * sorted out, this routine is called so we can tell the Host which features we
+ * understand and accept.
+ */
+static void lg_finalize_features(struct virtio_device *vdev)
+{
+ unsigned int i, bits;
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+ /* Second half of bitmap is features we accept. */
+ u8 *out_features = lg_features(desc) + desc->feature_len;
+
+ /* Give virtio_ring a chance to accept features. */
+ vring_transport_features(vdev);
+
+ /*
+ * The vdev->feature array is a Linux bitmask: this isn't the same as a
+ * the simple array of bits used by lguest devices for features. So we
+ * do this slow, manual conversion which is completely general.
+ */
+ memset(out_features, 0, desc->feature_len);
+ bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
+ for (i = 0; i < bits; i++) {
+ if (test_bit(i, vdev->features))
+ out_features[i / 8] |= (1 << (i % 8));
+ }
}
/* Once they've found a field, getting a copy of it is easy. */
-static void lg_get(struct virtio_device *vdev, void *token,
+static void lg_get(struct virtio_device *vdev, unsigned int offset,
void *buf, unsigned len)
{
- /* Check they didn't ask for more than the length of the field! */
- BUG_ON(len > ((u8 *)token)[1]);
- memcpy(buf, token + FHDR_LEN, len);
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+
+ /* Check they didn't ask for more than the length of the config! */
+ BUG_ON(offset + len > desc->config_len);
+ memcpy(buf, lg_config(desc) + offset, len);
}
/* Setting the contents is also trivial. */
-static void lg_set(struct virtio_device *vdev, void *token,
+static void lg_set(struct virtio_device *vdev, unsigned int offset,
const void *buf, unsigned len)
{
- BUG_ON(len > ((u8 *)token)[1]);
- memcpy(token + FHDR_LEN, buf, len);
+ struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
+
+ /* Check they didn't ask for more than the length of the config! */
+ BUG_ON(offset + len > desc->config_len);
+ memcpy(lg_config(desc) + offset, buf, len);
}
-/* The operations to get and set the status word just access the status field
- * of the device descriptor. */
+/*
+ * The operations to get and set the status word just access the status field
+ * of the device descriptor.
+ */
static u8 lg_get_status(struct virtio_device *vdev)
{
return to_lgdev(vdev)->desc->status;
}
-static void lg_set_status(struct virtio_device *vdev, u8 status)
+/*
+ * To notify on status updates, we (ab)use the NOTIFY hypercall, with the
+ * descriptor address of the device. A zero status means "reset".
+ */
+static void set_status(struct virtio_device *vdev, u8 status)
{
+ unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+ /* We set the status. */
to_lgdev(vdev)->desc->status = status;
+ kvm_hypercall1(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset);
+}
+
+static void lg_set_status(struct virtio_device *vdev, u8 status)
+{
+ BUG_ON(!status);
+ set_status(vdev, status);
+}
+
+static void lg_reset(struct virtio_device *vdev)
+{
+ set_status(vdev, 0);
}
/*
* The other piece of infrastructure virtio needs is a "virtqueue": a way of
* the Guest device registering buffers for the other side to read from or
* write into (ie. send and receive buffers). Each device can have multiple
- * virtqueues: for example the console has one queue for sending and one for
- * receiving.
+ * virtqueues: for example the console driver uses one queue for sending and
+ * another for receiving.
*
* Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue
* already exists in virtio_ring.c. We just need to connect it up.
*/
/*D:140 This is the information we remember about each virtqueue. */
-struct lguest_vq_info
-{
+struct lguest_vq_info {
/* A copy of the information contained in the device config. */
struct lguest_vqconfig config;
void *pages;
};
-/* When the virtio_ring code wants to prod the Host, it calls us here and we
- * make a hypercall. We hand the page number of the virtqueue so the Host
- * knows which virtqueue we're talking about. */
+/*
+ * When the virtio_ring code wants to prod the Host, it calls us here and we
+ * make a hypercall. We hand the physical address of the virtqueue so the Host
+ * knows which virtqueue we're talking about.
+ */
static void lg_notify(struct virtqueue *vq)
{
- /* We store our virtqueue information in the "priv" pointer of the
- * virtqueue structure. */
+ /*
+ * We store our virtqueue information in the "priv" pointer of the
+ * virtqueue structure.
+ */
struct lguest_vq_info *lvq = vq->priv;
- hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0);
+ kvm_hypercall1(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT);
}
-/* This routine finds the first virtqueue described in the configuration of
+/* An extern declaration inside a C file is bad form. Don't do it. */
+extern void lguest_setup_irq(unsigned int irq);
+
+/*
+ * This routine finds the Nth virtqueue described in the configuration of
* this device and sets it up.
*
* This is kind of an ugly duckling. It'd be nicer to have a standard
* representation of a virtqueue in the configuration space, but it seems that
- * everyone wants to do it differently. The KVM guys want the Guest to
+ * everyone wants to do it differently. The KVM coders want the Guest to
* allocate its own pages and tell the Host where they are, but for lguest it's
* simpler for the Host to simply tell us where the pages are.
- *
- * So we provide devices with a "find virtqueue and set it up" function. */
+ */
static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
- bool (*callback)(struct virtqueue *vq))
+ unsigned index,
+ void (*callback)(struct virtqueue *vq),
+ const char *name)
{
+ struct lguest_device *ldev = to_lgdev(vdev);
struct lguest_vq_info *lvq;
struct virtqueue *vq;
- unsigned int len;
- void *token;
int err;
- /* Look for a field of the correct type to mark a virtqueue. Note that
- * if this succeeds, then the type will be changed so it won't be found
- * again, and future lg_find_vq() calls will find the next
- * virtqueue (if any). */
- token = vdev->config->find(vdev, VIRTIO_CONFIG_F_VIRTQUEUE, &len);
- if (!token)
+ /* We must have this many virtqueues. */
+ if (index >= ldev->desc->num_vq)
return ERR_PTR(-ENOENT);
lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
if (!lvq)
return ERR_PTR(-ENOMEM);
- /* Note: we could use a configuration space inside here, just like we
- * do for the device. This would allow expansion in future, because
- * our configuration system is designed to be expansible. But this is
- * way easier. */
- if (len != sizeof(lvq->config)) {
- dev_err(&vdev->dev, "Unexpected virtio config len %u\n", len);
- err = -EIO;
- goto free_lvq;
- }
- /* Make a copy of the "struct lguest_vqconfig" field. We need a copy
- * because the config space might not be aligned correctly. */
- vdev->config->get(vdev, token, &lvq->config, sizeof(lvq->config));
+ /*
+ * Make a copy of the "struct lguest_vqconfig" entry, which sits after
+ * the descriptor. We need a copy because the config space might not
+ * be aligned correctly.
+ */
+ memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
+ printk("Mapping virtqueue %i addr %lx\n", index,
+ (unsigned long)lvq->config.pfn << PAGE_SHIFT);
/* Figure out how many pages the ring will take, and map that memory */
lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
- DIV_ROUND_UP(vring_size(lvq->config.num),
+ DIV_ROUND_UP(vring_size(lvq->config.num,
+ LGUEST_VRING_ALIGN),
PAGE_SIZE));
if (!lvq->pages) {
err = -ENOMEM;
goto free_lvq;
}
- /* OK, tell virtio_ring.c to set up a virtqueue now we know its size
- * and we've got a pointer to its pages. */
- vq = vring_new_virtqueue(lvq->config.num, vdev, lvq->pages,
- lg_notify, callback);
+ /*
+ * OK, tell virtio_ring.c to set up a virtqueue now we know its size
+ * and we've got a pointer to its pages.
+ */
+ vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
+ vdev, lvq->pages, lg_notify, callback, name);
if (!vq) {
err = -ENOMEM;
goto unmap;
}
- /* Tell the interrupt for this virtqueue to go to the virtio_ring
- * interrupt handler. */
- /* FIXME: We used to have a flag for the Host to tell us we could use
+ /* Make sure the interrupt is allocated. */
+ lguest_setup_irq(lvq->config.irq);
+
+ /*
+ * Tell the interrupt for this virtqueue to go to the virtio_ring
+ * interrupt handler.
+ *
+ * FIXME: We used to have a flag for the Host to tell us we could use
* the interrupt as a source of randomness: it'd be nice to have that
- * back.. */
+ * back.
+ */
err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
- vdev->dev.bus_id, vq);
+ dev_name(&vdev->dev), vq);
if (err)
goto destroy_vring;
- /* Last of all we hook up our 'struct lguest_vq_info" to the
- * virtqueue's priv pointer. */
+ /*
+ * Last of all we hook up our 'struct lguest_vq_info" to the
+ * virtqueue's priv pointer.
+ */
vq->priv = lvq;
return vq;
{
struct lguest_vq_info *lvq = vq->priv;
+ /* Release the interrupt */
+ free_irq(lvq->config.irq, vq);
/* Tell virtio_ring.c to free the virtqueue. */
vring_del_virtqueue(vq);
/* Unmap the pages containing the ring. */
kfree(lvq);
}
+static void lg_del_vqs(struct virtio_device *vdev)
+{
+ struct virtqueue *vq, *n;
+
+ list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+ lg_del_vq(vq);
+}
+
+static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+ struct virtqueue *vqs[],
+ vq_callback_t *callbacks[],
+ const char *names[])
+{
+ struct lguest_device *ldev = to_lgdev(vdev);
+ int i;
+
+ /* We must have this many virtqueues. */
+ if (nvqs > ldev->desc->num_vq)
+ return -ENOENT;
+
+ for (i = 0; i < nvqs; ++i) {
+ vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
+ if (IS_ERR(vqs[i]))
+ goto error;
+ }
+ return 0;
+
+error:
+ lg_del_vqs(vdev);
+ return PTR_ERR(vqs[i]);
+}
+
/* The ops structure which hooks everything together. */
static struct virtio_config_ops lguest_config_ops = {
- .find = lg_find,
+ .get_features = lg_get_features,
+ .finalize_features = lg_finalize_features,
.get = lg_get,
.set = lg_set,
.get_status = lg_get_status,
.set_status = lg_set_status,
- .find_vq = lg_find_vq,
- .del_vq = lg_del_vq,
+ .reset = lg_reset,
+ .find_vqs = lg_find_vqs,
+ .del_vqs = lg_del_vqs,
};
-/* The root device for the lguest virtio devices. This makes them appear as
- * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. */
-static struct device lguest_root = {
- .parent = NULL,
- .bus_id = "lguest",
-};
+/*
+ * The root device for the lguest virtio devices. This makes them appear as
+ * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
+ */
+static struct device *lguest_root;
-/*D:120 This is the core of the lguest bus: actually adding a new device.
+/*D:120
+ * This is the core of the lguest bus: actually adding a new device.
* It's a separate function because it's neater that way, and because an
* earlier version of the code supported hotplug and unplug. They were removed
* early on because they were never used.
* As Andrew Tridgell says, "Untested code is buggy code".
*
* It's worth reading this carefully: we start with a pointer to the new device
- * descriptor in the "lguest_devices" page. */
-static void add_lguest_device(struct lguest_device_desc *d)
+ * descriptor in the "lguest_devices" page, and the offset into the device
+ * descriptor page so we can uniquely identify it if things go badly wrong.
+ */
+static void add_lguest_device(struct lguest_device_desc *d,
+ unsigned int offset)
{
struct lguest_device *ldev;
+ /* Start with zeroed memory; Linux's device layer counts on it. */
ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
if (!ldev) {
- printk(KERN_EMERG "Cannot allocate lguest dev %u\n",
- dev_index++);
+ printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
+ offset, d->type);
return;
}
/* This devices' parent is the lguest/ dir. */
- ldev->vdev.dev.parent = &lguest_root;
- /* We have a unique device index thanks to the dev_index counter. */
- ldev->vdev.index = dev_index++;
- /* The device type comes straight from the descriptor. There's also a
+ ldev->vdev.dev.parent = lguest_root;
+ /*
+ * The device type comes straight from the descriptor. There's also a
* device vendor field in the virtio_device struct, which we leave as
- * 0. */
+ * 0.
+ */
ldev->vdev.id.device = d->type;
- /* We have a simple set of routines for querying the device's
- * configuration information and setting its status. */
+ /*
+ * We have a simple set of routines for querying the device's
+ * configuration information and setting its status.
+ */
ldev->vdev.config = &lguest_config_ops;
/* And we remember the device's descriptor for lguest_config_ops. */
ldev->desc = d;
- /* register_virtio_device() sets up the generic fields for the struct
+ /*
+ * register_virtio_device() sets up the generic fields for the struct
* virtio_device and calls device_register(). This makes the bus
- * infrastructure look for a matching driver. */
+ * infrastructure look for a matching driver.
+ */
if (register_virtio_device(&ldev->vdev) != 0) {
- printk(KERN_ERR "Failed to register lguest device %u\n",
- ldev->vdev.index);
+ printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
+ offset, d->type);
kfree(ldev);
}
}
-/*D:110 scan_devices() simply iterates through the device page. The type 0 is
- * reserved to mean "end of devices". */
+/*D:110
+ * scan_devices() simply iterates through the device page. The type 0 is
+ * reserved to mean "end of devices".
+ */
static void scan_devices(void)
{
unsigned int i;
struct lguest_device_desc *d;
/* We start at the page beginning, and skip over each entry. */
- for (i = 0; i < PAGE_SIZE; i += sizeof(*d) + d->config_len) {
+ for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
d = lguest_devices + i;
/* Once we hit a zero, stop. */
if (d->type == 0)
break;
- add_lguest_device(d);
+ printk("Device at %i has size %u\n", i, desc_size(d));
+ add_lguest_device(d, i);
}
}
-/*D:105 Fairly early in boot, lguest_devices_init() is called to set up the
+/*D:105
+ * Fairly early in boot, lguest_devices_init() is called to set up the
* lguest device infrastructure. We check that we are a Guest by checking
* pv_info.name: there are other ways of checking, but this seems most
* obvious to me.
* correct sysfs incantation).
*
* Finally we call scan_devices() which adds all the devices found in the
- * lguest_devices page. */
+ * lguest_devices page.
+ */
static int __init lguest_devices_init(void)
{
if (strcmp(pv_info.name, "lguest") != 0)
return 0;
- if (device_register(&lguest_root) != 0)
+ lguest_root = root_device_register("lguest");
+ if (IS_ERR(lguest_root))
panic("Could not register lguest root");
/* Devices are in a single page above top of "normal" mem */
/* We do this after core stuff, but before the drivers. */
postcore_initcall(lguest_devices_init);
-/*D:150 At this point in the journey we used to now wade through the lguest
+/*D:150
+ * At this point in the journey we used to now wade through the lguest
* devices themselves: net, block and console. Since they're all now virtio
* devices rather than lguest-specific, I've decided to ignore them. Mostly,
* they're kind of boring. But this does mean you'll never experience the
* thrill of reading the forbidden love scene buried deep in the block driver.
*
* "make Launcher" beckons, where we answer questions like "Where do Guests
- * come from?", and "What do you do when someone asks for optimization?". */
+ * come from?", and "What do you do when someone asks for optimization?".
+ */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff