+++ /dev/null
-/*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?".
- */
projects / platform / kernel / linux-rpi.git / commitdiff