mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
lguest: remove support for lguest bus.
The demonstration launcher now uses PCI entirely. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
parent
eb39f83372
commit
e68ccd1f9d
2 changed files with 0 additions and 543 deletions
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@ -1,6 +1,3 @@
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# Guest requires the device configuration and probing code.
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obj-$(CONFIG_LGUEST_GUEST) += lguest_device.o
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# Host requires the other files, which can be a module.
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obj-$(CONFIG_LGUEST) += lg.o
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lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
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@ -1,540 +0,0 @@
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/*P:050
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* Lguest guests use a very simple method to describe devices. It's a
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* series of device descriptors contained just above the top of normal Guest
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* memory.
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*
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* We use the standard "virtio" device infrastructure, which provides us with a
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* console, a network and a block driver. Each one expects some configuration
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* information and a "virtqueue" or two to send and receive data.
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:*/
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#include <linux/init.h>
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#include <linux/bootmem.h>
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#include <linux/lguest_launcher.h>
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#include <linux/virtio.h>
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#include <linux/virtio_config.h>
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#include <linux/interrupt.h>
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#include <linux/virtio_ring.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <asm/io.h>
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#include <asm/paravirt.h>
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#include <asm/lguest_hcall.h>
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/* The pointer to our (page) of device descriptions. */
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static void *lguest_devices;
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/*
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* For Guests, device memory can be used as normal memory, so we cast away the
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* __iomem to quieten sparse.
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*/
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static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
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{
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return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);
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}
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static inline void lguest_unmap(void *addr)
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{
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iounmap((__force void __iomem *)addr);
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}
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/*D:100
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* Each lguest device is just a virtio device plus a pointer to its entry
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* in the lguest_devices page.
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*/
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struct lguest_device {
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struct virtio_device vdev;
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/* The entry in the lguest_devices page for this device. */
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struct lguest_device_desc *desc;
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};
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/*
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* Since the virtio infrastructure hands us a pointer to the virtio_device all
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* the time, it helps to have a curt macro to get a pointer to the struct
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* lguest_device it's enclosed in.
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*/
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#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
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/*D:130
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* Device configurations
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*
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* The configuration information for a device consists of one or more
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* virtqueues, a feature bitmap, and some configuration bytes. The
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* configuration bytes don't really matter to us: the Launcher sets them up, and
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* the driver will look at them during setup.
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*
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* A convenient routine to return the device's virtqueue config array:
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* immediately after the descriptor.
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*/
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static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
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{
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return (void *)(desc + 1);
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}
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/* The features come immediately after the virtqueues. */
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static u8 *lg_features(const struct lguest_device_desc *desc)
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{
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return (void *)(lg_vq(desc) + desc->num_vq);
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}
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/* The config space comes after the two feature bitmasks. */
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static u8 *lg_config(const struct lguest_device_desc *desc)
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{
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return lg_features(desc) + desc->feature_len * 2;
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}
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/* The total size of the config page used by this device (incl. desc) */
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static unsigned desc_size(const struct lguest_device_desc *desc)
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{
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return sizeof(*desc)
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+ desc->num_vq * sizeof(struct lguest_vqconfig)
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+ desc->feature_len * 2
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+ desc->config_len;
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}
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/* This gets the device's feature bits. */
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static u64 lg_get_features(struct virtio_device *vdev)
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{
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unsigned int i;
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u32 features = 0;
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struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
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u8 *in_features = lg_features(desc);
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/* We do this the slow but generic way. */
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for (i = 0; i < min(desc->feature_len * 8, 32); i++)
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if (in_features[i / 8] & (1 << (i % 8)))
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features |= (1 << i);
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return features;
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}
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/*
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* To notify on reset or feature finalization, we (ab)use the NOTIFY
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* hypercall, with the descriptor address of the device.
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*/
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static void status_notify(struct virtio_device *vdev)
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{
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unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
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hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
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}
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/*
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* The virtio core takes the features the Host offers, and copies the ones
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* supported by the driver into the vdev->features array. Once that's all
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* sorted out, this routine is called so we can tell the Host which features we
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* understand and accept.
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*/
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static int lg_finalize_features(struct virtio_device *vdev)
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{
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unsigned int i, bits;
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struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
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/* Second half of bitmap is features we accept. */
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u8 *out_features = lg_features(desc) + desc->feature_len;
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/* Give virtio_ring a chance to accept features. */
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vring_transport_features(vdev);
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/* Make sure we don't have any features > 32 bits! */
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BUG_ON((u32)vdev->features != vdev->features);
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/*
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* Since lguest is currently x86-only, we're little-endian. That
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* means we could just memcpy. But it's not time critical, and in
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* case someone copies this code, we do it the slow, obvious way.
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*/
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memset(out_features, 0, desc->feature_len);
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bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
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for (i = 0; i < bits; i++) {
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if (__virtio_test_bit(vdev, i))
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out_features[i / 8] |= (1 << (i % 8));
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}
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/* Tell Host we've finished with this device's feature negotiation */
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status_notify(vdev);
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return 0;
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}
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/* Once they've found a field, getting a copy of it is easy. */
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static void lg_get(struct virtio_device *vdev, unsigned int offset,
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void *buf, unsigned len)
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{
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struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
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/* Check they didn't ask for more than the length of the config! */
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BUG_ON(offset + len > desc->config_len);
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memcpy(buf, lg_config(desc) + offset, len);
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}
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/* Setting the contents is also trivial. */
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static void lg_set(struct virtio_device *vdev, unsigned int offset,
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const void *buf, unsigned len)
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{
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struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
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/* Check they didn't ask for more than the length of the config! */
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BUG_ON(offset + len > desc->config_len);
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memcpy(lg_config(desc) + offset, buf, len);
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}
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/*
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* The operations to get and set the status word just access the status field
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* of the device descriptor.
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*/
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static u8 lg_get_status(struct virtio_device *vdev)
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{
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return to_lgdev(vdev)->desc->status;
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}
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static void lg_set_status(struct virtio_device *vdev, u8 status)
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{
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BUG_ON(!status);
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to_lgdev(vdev)->desc->status = status;
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/* Tell Host immediately if we failed. */
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if (status & VIRTIO_CONFIG_S_FAILED)
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status_notify(vdev);
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}
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static void lg_reset(struct virtio_device *vdev)
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{
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/* 0 status means "reset" */
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to_lgdev(vdev)->desc->status = 0;
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status_notify(vdev);
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}
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/*
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* Virtqueues
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*
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* The other piece of infrastructure virtio needs is a "virtqueue": a way of
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* the Guest device registering buffers for the other side to read from or
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* write into (ie. send and receive buffers). Each device can have multiple
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* virtqueues: for example the console driver uses one queue for sending and
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* another for receiving.
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*
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* Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue
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* already exists in virtio_ring.c. We just need to connect it up.
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*
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* We start with the information we need to keep about each virtqueue.
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*/
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/*D:140 This is the information we remember about each virtqueue. */
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struct lguest_vq_info {
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/* A copy of the information contained in the device config. */
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struct lguest_vqconfig config;
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/* The address where we mapped the virtio ring, so we can unmap it. */
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void *pages;
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};
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/*
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* When the virtio_ring code wants to prod the Host, it calls us here and we
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* make a hypercall. We hand the physical address of the virtqueue so the Host
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* knows which virtqueue we're talking about.
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*/
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static bool lg_notify(struct virtqueue *vq)
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{
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/*
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* We store our virtqueue information in the "priv" pointer of the
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* virtqueue structure.
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*/
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struct lguest_vq_info *lvq = vq->priv;
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hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0);
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return true;
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}
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/* An extern declaration inside a C file is bad form. Don't do it. */
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extern int lguest_setup_irq(unsigned int irq);
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/*
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* This routine finds the Nth virtqueue described in the configuration of
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* this device and sets it up.
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*
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* This is kind of an ugly duckling. It'd be nicer to have a standard
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* representation of a virtqueue in the configuration space, but it seems that
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* everyone wants to do it differently. The KVM coders want the Guest to
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* allocate its own pages and tell the Host where they are, but for lguest it's
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* simpler for the Host to simply tell us where the pages are.
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*/
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static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
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unsigned index,
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void (*callback)(struct virtqueue *vq),
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const char *name)
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{
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struct lguest_device *ldev = to_lgdev(vdev);
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struct lguest_vq_info *lvq;
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struct virtqueue *vq;
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int err;
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if (!name)
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return NULL;
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/* We must have this many virtqueues. */
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if (index >= ldev->desc->num_vq)
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return ERR_PTR(-ENOENT);
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lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
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if (!lvq)
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return ERR_PTR(-ENOMEM);
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/*
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* Make a copy of the "struct lguest_vqconfig" entry, which sits after
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* the descriptor. We need a copy because the config space might not
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* be aligned correctly.
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*/
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memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
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printk("Mapping virtqueue %i addr %lx\n", index,
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(unsigned long)lvq->config.pfn << PAGE_SHIFT);
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/* Figure out how many pages the ring will take, and map that memory */
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lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
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DIV_ROUND_UP(vring_size(lvq->config.num,
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LGUEST_VRING_ALIGN),
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PAGE_SIZE));
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if (!lvq->pages) {
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err = -ENOMEM;
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goto free_lvq;
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}
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/*
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* OK, tell virtio_ring.c to set up a virtqueue now we know its size
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* and we've got a pointer to its pages. Note that we set weak_barriers
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* to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu
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* barriers.
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*/
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vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,
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true, lvq->pages, lg_notify, callback, name);
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if (!vq) {
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err = -ENOMEM;
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goto unmap;
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}
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/* Make sure the interrupt is allocated. */
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err = lguest_setup_irq(lvq->config.irq);
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if (err)
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goto destroy_vring;
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/*
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* Tell the interrupt for this virtqueue to go to the virtio_ring
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* interrupt handler.
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*
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* FIXME: We used to have a flag for the Host to tell us we could use
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* the interrupt as a source of randomness: it'd be nice to have that
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* back.
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*/
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err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
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dev_name(&vdev->dev), vq);
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if (err)
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goto free_desc;
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/*
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* Last of all we hook up our 'struct lguest_vq_info" to the
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* virtqueue's priv pointer.
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*/
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vq->priv = lvq;
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return vq;
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free_desc:
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irq_free_desc(lvq->config.irq);
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destroy_vring:
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vring_del_virtqueue(vq);
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unmap:
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lguest_unmap(lvq->pages);
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free_lvq:
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kfree(lvq);
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return ERR_PTR(err);
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}
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/*:*/
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/* Cleaning up a virtqueue is easy */
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static void lg_del_vq(struct virtqueue *vq)
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{
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struct lguest_vq_info *lvq = vq->priv;
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/* Release the interrupt */
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free_irq(lvq->config.irq, vq);
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/* Tell virtio_ring.c to free the virtqueue. */
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vring_del_virtqueue(vq);
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/* Unmap the pages containing the ring. */
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lguest_unmap(lvq->pages);
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/* Free our own queue information. */
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kfree(lvq);
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}
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static void lg_del_vqs(struct virtio_device *vdev)
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{
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struct virtqueue *vq, *n;
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list_for_each_entry_safe(vq, n, &vdev->vqs, list)
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lg_del_vq(vq);
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}
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static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
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struct virtqueue *vqs[],
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vq_callback_t *callbacks[],
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const char *names[])
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{
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struct lguest_device *ldev = to_lgdev(vdev);
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int i;
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/* We must have this many virtqueues. */
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if (nvqs > ldev->desc->num_vq)
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return -ENOENT;
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for (i = 0; i < nvqs; ++i) {
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vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
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if (IS_ERR(vqs[i]))
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goto error;
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}
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return 0;
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error:
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lg_del_vqs(vdev);
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return PTR_ERR(vqs[i]);
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}
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static const char *lg_bus_name(struct virtio_device *vdev)
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{
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return "";
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}
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/* The ops structure which hooks everything together. */
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static const struct virtio_config_ops lguest_config_ops = {
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.get_features = lg_get_features,
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.finalize_features = lg_finalize_features,
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.get = lg_get,
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.set = lg_set,
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.get_status = lg_get_status,
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.set_status = lg_set_status,
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.reset = lg_reset,
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.find_vqs = lg_find_vqs,
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.del_vqs = lg_del_vqs,
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.bus_name = lg_bus_name,
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};
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/*
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* The root device for the lguest virtio devices. This makes them appear as
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* /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
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*/
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static struct device *lguest_root;
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/*D:120
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* This is the core of the lguest bus: actually adding a new device.
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* It's a separate function because it's neater that way, and because an
|
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* earlier version of the code supported hotplug and unplug. They were removed
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* early on because they were never used.
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*
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* As Andrew Tridgell says, "Untested code is buggy code".
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*
|
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* It's worth reading this carefully: we start with a pointer to the new device
|
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* descriptor in the "lguest_devices" page, and the offset into the device
|
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* descriptor page so we can uniquely identify it if things go badly wrong.
|
||||
*/
|
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static void add_lguest_device(struct lguest_device_desc *d,
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unsigned int offset)
|
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{
|
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struct lguest_device *ldev;
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|
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/* Start with zeroed memory; Linux's device layer counts on it. */
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ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
|
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if (!ldev) {
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printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
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offset, d->type);
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return;
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}
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/* This devices' parent is the lguest/ dir. */
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ldev->vdev.dev.parent = lguest_root;
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/*
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||||
* 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?".
|
||||
*/
|
||||
Loading…
Reference in a new issue