diff options
Diffstat (limited to 'drivers/lguest/lguest_device.c')
| -rw-r--r-- | drivers/lguest/lguest_device.c | 540 |
1 files changed, 0 insertions, 540 deletions
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c deleted file mode 100644 index 89088d6538fd..000000000000 --- a/drivers/lguest/lguest_device.c +++ /dev/null @@ -1,540 +0,0 @@ -/*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" or two to send and receive data. -:*/ -#include <linux/init.h> -#include <linux/bootmem.h> -#include <linux/lguest_launcher.h> -#include <linux/virtio.h> -#include <linux/virtio_config.h> -#include <linux/interrupt.h> -#include <linux/virtio_ring.h> -#include <linux/err.h> -#include <linux/export.h> -#include <linux/slab.h> -#include <asm/io.h> -#include <asm/paravirt.h> -#include <asm/lguest_hcall.h> - -/* The pointer to our (page) of device descriptions. */ -static void *lguest_devices; - -/* - * 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_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. - */ -struct lguest_device { - struct virtio_device vdev; - - /* The entry in the lguest_devices page for this device. */ - struct lguest_device_desc *desc; -}; - -/* - * 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(vd) container_of(vd, struct lguest_device, vdev) - -/*D:130 - * Device configurations - * - * 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. - * - * 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; -} - -/* 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 gets the device's feature bits. */ -static u64 lg_get_features(struct virtio_device *vdev) -{ - unsigned int i; - u32 features = 0; - struct lguest_device_desc *desc = to_lgdev(vdev)->desc; - u8 *in_features = lg_features(desc); - - /* 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); - - return features; -} - -/* - * To notify on reset or feature finalization, we (ab)use the NOTIFY - * hypercall, with the descriptor address of the device. - */ -static void status_notify(struct virtio_device *vdev) -{ - unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices; - - hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0); -} - -/* - * 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 int 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); - - /* Make sure we don't have any features > 32 bits! */ - BUG_ON((u32)vdev->features != vdev->features); - - /* - * Since lguest is currently x86-only, we're little-endian. That - * means we could just memcpy. But it's not time critical, and in - * case someone copies this code, we do it the slow, obvious way. - */ - 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 (__virtio_test_bit(vdev, i)) - out_features[i / 8] |= (1 << (i % 8)); - } - - /* Tell Host we've finished with this device's feature negotiation */ - status_notify(vdev); - - return 0; -} - -/* Once they've found a field, getting a copy of it is easy. */ -static void lg_get(struct virtio_device *vdev, unsigned int offset, - void *buf, unsigned 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, unsigned int offset, - const void *buf, unsigned 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. - */ -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) -{ - BUG_ON(!status); - to_lgdev(vdev)->desc->status = status; - - /* Tell Host immediately if we failed. */ - if (status & VIRTIO_CONFIG_S_FAILED) - status_notify(vdev); -} - -static void lg_reset(struct virtio_device *vdev) -{ - /* 0 status means "reset" */ - to_lgdev(vdev)->desc->status = 0; - status_notify(vdev); -} - -/* - * Virtqueues - * - * 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 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. - * - * We start with the information we need to keep about each virtqueue. - */ - -/*D:140 This is the information we remember about each virtqueue. */ -struct lguest_vq_info { - /* A copy of the information contained in the device config. */ - struct lguest_vqconfig config; - - /* The address where we mapped the virtio ring, so we can unmap it. */ - void *pages; -}; - -/* - * 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 bool lg_notify(struct virtqueue *vq) -{ - /* - * 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, 0); - return true; -} - -/* An extern declaration inside a C file is bad form. Don't do it. */ -extern int 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 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. - */ -static struct virtqueue *lg_find_vq(struct virtio_device *vdev, - 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; - int err; - - if (!name) - return NULL; - - /* 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); - - /* - * 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, - 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. Note that we set weak_barriers - * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu - * barriers. - */ - vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev, - true, lvq->pages, lg_notify, callback, name); - if (!vq) { - err = -ENOMEM; - goto unmap; - } - - /* Make sure the interrupt is allocated. */ - err = lguest_setup_irq(lvq->config.irq); - if (err) - goto destroy_vring; - - /* - * 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. - */ - err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED, - dev_name(&vdev->dev), vq); - if (err) - goto free_desc; - - /* - * Last of all we hook up our 'struct lguest_vq_info" to the - * virtqueue's priv pointer. - */ - vq->priv = lvq; - return vq; - -free_desc: - irq_free_desc(lvq->config.irq); -destroy_vring: - vring_del_virtqueue(vq); -unmap: - lguest_unmap(lvq->pages); -free_lvq: - kfree(lvq); - return ERR_PTR(err); -} -/*:*/ - -/* Cleaning up a virtqueue is easy */ -static void lg_del_vq(struct virtqueue *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. */ - lguest_unmap(lvq->pages); - /* Free our own queue information. */ - 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]); -} - -static const char *lg_bus_name(struct virtio_device *vdev) -{ - return ""; -} - -/* The ops structure which hooks everything together. */ -static const struct virtio_config_ops lguest_config_ops = { - .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, - .reset = lg_reset, - .find_vqs = lg_find_vqs, - .del_vqs = lg_del_vqs, - .bus_name = lg_bus_name, -}; - -/* - * 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. - * 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, 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 type %u\n", - offset, d->type); - return; - } - - /* This devices' parent is the lguest/ dir. */ - 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. - */ - ldev->vdev.id.device = d->type; - /* - * 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 - * virtio_device and calls device_register(). This makes the bus - * infrastructure look for a matching driver. - */ - if (register_virtio_device(&ldev->vdev) != 0) { - 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". - */ -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 += desc_size(d)) { - d = lguest_devices + i; - - /* Once we hit a zero, stop. */ - if (d->type == 0) - break; - - 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 - * 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. - * - * So we can access the "struct lguest_device_desc"s easily, we map that memory - * and store the pointer in the global "lguest_devices". Then we register a - * root device from which all our devices will hang (this seems to be the - * correct sysfs incantation). - * - * Finally we call scan_devices() which adds all the devices found in the - * lguest_devices page. - */ -static int __init lguest_devices_init(void) -{ - if (strcmp(pv_info.name, "lguest") != 0) - return 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 */ - lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1); - - scan_devices(); - return 0; -} -/* 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 - * 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?". - */ |