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authorDavidlohr Bueso <dave@gnu.org>2012-01-12 00:14:47 -0500
committerRusty Russell <rusty@rustcorp.com.au>2012-01-12 00:14:47 -0500
commit07fe9977b6234ede1bd29e10e0323e478860c871 (patch)
tree802e48e78503b82953b9ff415f882fb6edb05dbc /Documentation/virtual
parent39082f7e5912cdc70f9ab0767e7342711f34b9f8 (diff)
lguest: move the lguest tool to the tools directory
This is a better location instead of having it in Documentation. Signed-off-by: Davidlohr Bueso <dave@gnu.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (fixed compile)
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/lguest/.gitignore1
-rw-r--r--Documentation/virtual/lguest/Makefile8
-rw-r--r--Documentation/virtual/lguest/extract58
-rw-r--r--Documentation/virtual/lguest/lguest.c2065
-rw-r--r--Documentation/virtual/lguest/lguest.txt129
5 files changed, 0 insertions, 2261 deletions
diff --git a/Documentation/virtual/lguest/.gitignore b/Documentation/virtual/lguest/.gitignore
deleted file mode 100644
index 115587fd5f65..000000000000
--- a/Documentation/virtual/lguest/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
1lguest
diff --git a/Documentation/virtual/lguest/Makefile b/Documentation/virtual/lguest/Makefile
deleted file mode 100644
index 0ac34206f7a7..000000000000
--- a/Documentation/virtual/lguest/Makefile
+++ /dev/null
@@ -1,8 +0,0 @@
1# This creates the demonstration utility "lguest" which runs a Linux guest.
2# Missing headers? Add "-I../../../include -I../../../arch/x86/include"
3CFLAGS:=-m32 -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -U_FORTIFY_SOURCE
4
5all: lguest
6
7clean:
8 rm -f lguest
diff --git a/Documentation/virtual/lguest/extract b/Documentation/virtual/lguest/extract
deleted file mode 100644
index 7730bb6e4b94..000000000000
--- a/Documentation/virtual/lguest/extract
+++ /dev/null
@@ -1,58 +0,0 @@
1#! /bin/sh
2
3set -e
4
5PREFIX=$1
6shift
7
8trap 'rm -r $TMPDIR' 0
9TMPDIR=`mktemp -d`
10
11exec 3>/dev/null
12for f; do
13 while IFS="
14" read -r LINE; do
15 case "$LINE" in
16 *$PREFIX:[0-9]*:\**)
17 NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"`
18 if [ -f $TMPDIR/$NUM ]; then
19 echo "$TMPDIR/$NUM already exits prior to $f"
20 exit 1
21 fi
22 exec 3>>$TMPDIR/$NUM
23 echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM
24 /bin/echo "$LINE" | sed -e "s/$PREFIX:[0-9]*//" -e "s/:\*/*/" >&3
25 ;;
26 *$PREFIX:[0-9]*)
27 NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"`
28 if [ -f $TMPDIR/$NUM ]; then
29 echo "$TMPDIR/$NUM already exits prior to $f"
30 exit 1
31 fi
32 exec 3>>$TMPDIR/$NUM
33 echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM
34 /bin/echo "$LINE" | sed "s/$PREFIX:[0-9]*//" >&3
35 ;;
36 *:\**)
37 /bin/echo "$LINE" | sed -e "s/:\*/*/" -e "s,/\*\*/,," >&3
38 echo >&3
39 exec 3>/dev/null
40 ;;
41 *)
42 /bin/echo "$LINE" >&3
43 ;;
44 esac
45 done < $f
46 echo >&3
47 exec 3>/dev/null
48done
49
50LASTFILE=""
51for f in $TMPDIR/*; do
52 if [ "$LASTFILE" != $(cat $TMPDIR/.$(basename $f) ) ]; then
53 LASTFILE=$(cat $TMPDIR/.$(basename $f) )
54 echo "[ $LASTFILE ]"
55 fi
56 cat $f
57done
58
diff --git a/Documentation/virtual/lguest/lguest.c b/Documentation/virtual/lguest/lguest.c
deleted file mode 100644
index c095d79cae73..000000000000
--- a/Documentation/virtual/lguest/lguest.c
+++ /dev/null
@@ -1,2065 +0,0 @@
1/*P:100
2 * This is the Launcher code, a simple program which lays out the "physical"
3 * memory for the new Guest by mapping the kernel image and the virtual
4 * devices, then opens /dev/lguest to tell the kernel about the Guest and
5 * control it.
6:*/
7#define _LARGEFILE64_SOURCE
8#define _GNU_SOURCE
9#include <stdio.h>
10#include <string.h>
11#include <unistd.h>
12#include <err.h>
13#include <stdint.h>
14#include <stdlib.h>
15#include <elf.h>
16#include <sys/mman.h>
17#include <sys/param.h>
18#include <sys/types.h>
19#include <sys/stat.h>
20#include <sys/wait.h>
21#include <sys/eventfd.h>
22#include <fcntl.h>
23#include <stdbool.h>
24#include <errno.h>
25#include <ctype.h>
26#include <sys/socket.h>
27#include <sys/ioctl.h>
28#include <sys/time.h>
29#include <time.h>
30#include <netinet/in.h>
31#include <net/if.h>
32#include <linux/sockios.h>
33#include <linux/if_tun.h>
34#include <sys/uio.h>
35#include <termios.h>
36#include <getopt.h>
37#include <assert.h>
38#include <sched.h>
39#include <limits.h>
40#include <stddef.h>
41#include <signal.h>
42#include <pwd.h>
43#include <grp.h>
44
45#include <linux/virtio_config.h>
46#include <linux/virtio_net.h>
47#include <linux/virtio_blk.h>
48#include <linux/virtio_console.h>
49#include <linux/virtio_rng.h>
50#include <linux/virtio_ring.h>
51#include <asm/bootparam.h>
52#include "../../../include/linux/lguest_launcher.h"
53/*L:110
54 * We can ignore the 43 include files we need for this program, but I do want
55 * to draw attention to the use of kernel-style types.
56 *
57 * As Linus said, "C is a Spartan language, and so should your naming be." I
58 * like these abbreviations, so we define them here. Note that u64 is always
59 * unsigned long long, which works on all Linux systems: this means that we can
60 * use %llu in printf for any u64.
61 */
62typedef unsigned long long u64;
63typedef uint32_t u32;
64typedef uint16_t u16;
65typedef uint8_t u8;
66/*:*/
67
68#define BRIDGE_PFX "bridge:"
69#ifndef SIOCBRADDIF
70#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
71#endif
72/* We can have up to 256 pages for devices. */
73#define DEVICE_PAGES 256
74/* This will occupy 3 pages: it must be a power of 2. */
75#define VIRTQUEUE_NUM 256
76
77/*L:120
78 * verbose is both a global flag and a macro. The C preprocessor allows
79 * this, and although I wouldn't recommend it, it works quite nicely here.
80 */
81static bool verbose;
82#define verbose(args...) \
83 do { if (verbose) printf(args); } while(0)
84/*:*/
85
86/* The pointer to the start of guest memory. */
87static void *guest_base;
88/* The maximum guest physical address allowed, and maximum possible. */
89static unsigned long guest_limit, guest_max;
90/* The /dev/lguest file descriptor. */
91static int lguest_fd;
92
93/* a per-cpu variable indicating whose vcpu is currently running */
94static unsigned int __thread cpu_id;
95
96/* This is our list of devices. */
97struct device_list {
98 /* Counter to assign interrupt numbers. */
99 unsigned int next_irq;
100
101 /* Counter to print out convenient device numbers. */
102 unsigned int device_num;
103
104 /* The descriptor page for the devices. */
105 u8 *descpage;
106
107 /* A single linked list of devices. */
108 struct device *dev;
109 /* And a pointer to the last device for easy append. */
110 struct device *lastdev;
111};
112
113/* The list of Guest devices, based on command line arguments. */
114static struct device_list devices;
115
116/* The device structure describes a single device. */
117struct device {
118 /* The linked-list pointer. */
119 struct device *next;
120
121 /* The device's descriptor, as mapped into the Guest. */
122 struct lguest_device_desc *desc;
123
124 /* We can't trust desc values once Guest has booted: we use these. */
125 unsigned int feature_len;
126 unsigned int num_vq;
127
128 /* The name of this device, for --verbose. */
129 const char *name;
130
131 /* Any queues attached to this device */
132 struct virtqueue *vq;
133
134 /* Is it operational */
135 bool running;
136
137 /* Device-specific data. */
138 void *priv;
139};
140
141/* The virtqueue structure describes a queue attached to a device. */
142struct virtqueue {
143 struct virtqueue *next;
144
145 /* Which device owns me. */
146 struct device *dev;
147
148 /* The configuration for this queue. */
149 struct lguest_vqconfig config;
150
151 /* The actual ring of buffers. */
152 struct vring vring;
153
154 /* Last available index we saw. */
155 u16 last_avail_idx;
156
157 /* How many are used since we sent last irq? */
158 unsigned int pending_used;
159
160 /* Eventfd where Guest notifications arrive. */
161 int eventfd;
162
163 /* Function for the thread which is servicing this virtqueue. */
164 void (*service)(struct virtqueue *vq);
165 pid_t thread;
166};
167
168/* Remember the arguments to the program so we can "reboot" */
169static char **main_args;
170
171/* The original tty settings to restore on exit. */
172static struct termios orig_term;
173
174/*
175 * We have to be careful with barriers: our devices are all run in separate
176 * threads and so we need to make sure that changes visible to the Guest happen
177 * in precise order.
178 */
179#define wmb() __asm__ __volatile__("" : : : "memory")
180#define mb() __asm__ __volatile__("" : : : "memory")
181
182/*
183 * Convert an iovec element to the given type.
184 *
185 * This is a fairly ugly trick: we need to know the size of the type and
186 * alignment requirement to check the pointer is kosher. It's also nice to
187 * have the name of the type in case we report failure.
188 *
189 * Typing those three things all the time is cumbersome and error prone, so we
190 * have a macro which sets them all up and passes to the real function.
191 */
192#define convert(iov, type) \
193 ((type *)_convert((iov), sizeof(type), __alignof__(type), #type))
194
195static void *_convert(struct iovec *iov, size_t size, size_t align,
196 const char *name)
197{
198 if (iov->iov_len != size)
199 errx(1, "Bad iovec size %zu for %s", iov->iov_len, name);
200 if ((unsigned long)iov->iov_base % align != 0)
201 errx(1, "Bad alignment %p for %s", iov->iov_base, name);
202 return iov->iov_base;
203}
204
205/* Wrapper for the last available index. Makes it easier to change. */
206#define lg_last_avail(vq) ((vq)->last_avail_idx)
207
208/*
209 * The virtio configuration space is defined to be little-endian. x86 is
210 * little-endian too, but it's nice to be explicit so we have these helpers.
211 */
212#define cpu_to_le16(v16) (v16)
213#define cpu_to_le32(v32) (v32)
214#define cpu_to_le64(v64) (v64)
215#define le16_to_cpu(v16) (v16)
216#define le32_to_cpu(v32) (v32)
217#define le64_to_cpu(v64) (v64)
218
219/* Is this iovec empty? */
220static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
221{
222 unsigned int i;
223
224 for (i = 0; i < num_iov; i++)
225 if (iov[i].iov_len)
226 return false;
227 return true;
228}
229
230/* Take len bytes from the front of this iovec. */
231static void iov_consume(struct iovec iov[], unsigned num_iov, unsigned len)
232{
233 unsigned int i;
234
235 for (i = 0; i < num_iov; i++) {
236 unsigned int used;
237
238 used = iov[i].iov_len < len ? iov[i].iov_len : len;
239 iov[i].iov_base += used;
240 iov[i].iov_len -= used;
241 len -= used;
242 }
243 assert(len == 0);
244}
245
246/* The device virtqueue descriptors are followed by feature bitmasks. */
247static u8 *get_feature_bits(struct device *dev)
248{
249 return (u8 *)(dev->desc + 1)
250 + dev->num_vq * sizeof(struct lguest_vqconfig);
251}
252
253/*L:100
254 * The Launcher code itself takes us out into userspace, that scary place where
255 * pointers run wild and free! Unfortunately, like most userspace programs,
256 * it's quite boring (which is why everyone likes to hack on the kernel!).
257 * Perhaps if you make up an Lguest Drinking Game at this point, it will get
258 * you through this section. Or, maybe not.
259 *
260 * The Launcher sets up a big chunk of memory to be the Guest's "physical"
261 * memory and stores it in "guest_base". In other words, Guest physical ==
262 * Launcher virtual with an offset.
263 *
264 * This can be tough to get your head around, but usually it just means that we
265 * use these trivial conversion functions when the Guest gives us its
266 * "physical" addresses:
267 */
268static void *from_guest_phys(unsigned long addr)
269{
270 return guest_base + addr;
271}
272
273static unsigned long to_guest_phys(const void *addr)
274{
275 return (addr - guest_base);
276}
277
278/*L:130
279 * Loading the Kernel.
280 *
281 * We start with couple of simple helper routines. open_or_die() avoids
282 * error-checking code cluttering the callers:
283 */
284static int open_or_die(const char *name, int flags)
285{
286 int fd = open(name, flags);
287 if (fd < 0)
288 err(1, "Failed to open %s", name);
289 return fd;
290}
291
292/* map_zeroed_pages() takes a number of pages. */
293static void *map_zeroed_pages(unsigned int num)
294{
295 int fd = open_or_die("/dev/zero", O_RDONLY);
296 void *addr;
297
298 /*
299 * We use a private mapping (ie. if we write to the page, it will be
300 * copied). We allocate an extra two pages PROT_NONE to act as guard
301 * pages against read/write attempts that exceed allocated space.
302 */
303 addr = mmap(NULL, getpagesize() * (num+2),
304 PROT_NONE, MAP_PRIVATE, fd, 0);
305
306 if (addr == MAP_FAILED)
307 err(1, "Mmapping %u pages of /dev/zero", num);
308
309 if (mprotect(addr + getpagesize(), getpagesize() * num,
310 PROT_READ|PROT_WRITE) == -1)
311 err(1, "mprotect rw %u pages failed", num);
312
313 /*
314 * One neat mmap feature is that you can close the fd, and it
315 * stays mapped.
316 */
317 close(fd);
318
319 /* Return address after PROT_NONE page */
320 return addr + getpagesize();
321}
322
323/* Get some more pages for a device. */
324static void *get_pages(unsigned int num)
325{
326 void *addr = from_guest_phys(guest_limit);
327
328 guest_limit += num * getpagesize();
329 if (guest_limit > guest_max)
330 errx(1, "Not enough memory for devices");
331 return addr;
332}
333
334/*
335 * This routine is used to load the kernel or initrd. It tries mmap, but if
336 * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
337 * it falls back to reading the memory in.
338 */
339static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
340{
341 ssize_t r;
342
343 /*
344 * We map writable even though for some segments are marked read-only.
345 * The kernel really wants to be writable: it patches its own
346 * instructions.
347 *
348 * MAP_PRIVATE means that the page won't be copied until a write is
349 * done to it. This allows us to share untouched memory between
350 * Guests.
351 */
352 if (mmap(addr, len, PROT_READ|PROT_WRITE,
353 MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
354 return;
355
356 /* pread does a seek and a read in one shot: saves a few lines. */
357 r = pread(fd, addr, len, offset);
358 if (r != len)
359 err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
360}
361
362/*
363 * This routine takes an open vmlinux image, which is in ELF, and maps it into
364 * the Guest memory. ELF = Embedded Linking Format, which is the format used
365 * by all modern binaries on Linux including the kernel.
366 *
367 * The ELF headers give *two* addresses: a physical address, and a virtual
368 * address. We use the physical address; the Guest will map itself to the
369 * virtual address.
370 *
371 * We return the starting address.
372 */
373static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
374{
375 Elf32_Phdr phdr[ehdr->e_phnum];
376 unsigned int i;
377
378 /*
379 * Sanity checks on the main ELF header: an x86 executable with a
380 * reasonable number of correctly-sized program headers.
381 */
382 if (ehdr->e_type != ET_EXEC
383 || ehdr->e_machine != EM_386
384 || ehdr->e_phentsize != sizeof(Elf32_Phdr)
385 || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
386 errx(1, "Malformed elf header");
387
388 /*
389 * An ELF executable contains an ELF header and a number of "program"
390 * headers which indicate which parts ("segments") of the program to
391 * load where.
392 */
393
394 /* We read in all the program headers at once: */
395 if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
396 err(1, "Seeking to program headers");
397 if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
398 err(1, "Reading program headers");
399
400 /*
401 * Try all the headers: there are usually only three. A read-only one,
402 * a read-write one, and a "note" section which we don't load.
403 */
404 for (i = 0; i < ehdr->e_phnum; i++) {
405 /* If this isn't a loadable segment, we ignore it */
406 if (phdr[i].p_type != PT_LOAD)
407 continue;
408
409 verbose("Section %i: size %i addr %p\n",
410 i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
411
412 /* We map this section of the file at its physical address. */
413 map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
414 phdr[i].p_offset, phdr[i].p_filesz);
415 }
416
417 /* The entry point is given in the ELF header. */
418 return ehdr->e_entry;
419}
420
421/*L:150
422 * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed
423 * to jump into it and it will unpack itself. We used to have to perform some
424 * hairy magic because the unpacking code scared me.
425 *
426 * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
427 * a small patch to jump over the tricky bits in the Guest, so now we just read
428 * the funky header so we know where in the file to load, and away we go!
429 */
430static unsigned long load_bzimage(int fd)
431{
432 struct boot_params boot;
433 int r;
434 /* Modern bzImages get loaded at 1M. */
435 void *p = from_guest_phys(0x100000);
436
437 /*
438 * Go back to the start of the file and read the header. It should be
439 * a Linux boot header (see Documentation/x86/boot.txt)
440 */
441 lseek(fd, 0, SEEK_SET);
442 read(fd, &boot, sizeof(boot));
443
444 /* Inside the setup_hdr, we expect the magic "HdrS" */
445 if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
446 errx(1, "This doesn't look like a bzImage to me");
447
448 /* Skip over the extra sectors of the header. */
449 lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
450
451 /* Now read everything into memory. in nice big chunks. */
452 while ((r = read(fd, p, 65536)) > 0)
453 p += r;
454
455 /* Finally, code32_start tells us where to enter the kernel. */
456 return boot.hdr.code32_start;
457}
458
459/*L:140
460 * Loading the kernel is easy when it's a "vmlinux", but most kernels
461 * come wrapped up in the self-decompressing "bzImage" format. With a little
462 * work, we can load those, too.
463 */
464static unsigned long load_kernel(int fd)
465{
466 Elf32_Ehdr hdr;
467
468 /* Read in the first few bytes. */
469 if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
470 err(1, "Reading kernel");
471
472 /* If it's an ELF file, it starts with "\177ELF" */
473 if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
474 return map_elf(fd, &hdr);
475
476 /* Otherwise we assume it's a bzImage, and try to load it. */
477 return load_bzimage(fd);
478}
479
480/*
481 * This is a trivial little helper to align pages. Andi Kleen hated it because
482 * it calls getpagesize() twice: "it's dumb code."
483 *
484 * Kernel guys get really het up about optimization, even when it's not
485 * necessary. I leave this code as a reaction against that.
486 */
487static inline unsigned long page_align(unsigned long addr)
488{
489 /* Add upwards and truncate downwards. */
490 return ((addr + getpagesize()-1) & ~(getpagesize()-1));
491}
492
493/*L:180
494 * An "initial ram disk" is a disk image loaded into memory along with the
495 * kernel which the kernel can use to boot from without needing any drivers.
496 * Most distributions now use this as standard: the initrd contains the code to
497 * load the appropriate driver modules for the current machine.
498 *
499 * Importantly, James Morris works for RedHat, and Fedora uses initrds for its
500 * kernels. He sent me this (and tells me when I break it).
501 */
502static unsigned long load_initrd(const char *name, unsigned long mem)
503{
504 int ifd;
505 struct stat st;
506 unsigned long len;
507
508 ifd = open_or_die(name, O_RDONLY);
509 /* fstat() is needed to get the file size. */
510 if (fstat(ifd, &st) < 0)
511 err(1, "fstat() on initrd '%s'", name);
512
513 /*
514 * We map the initrd at the top of memory, but mmap wants it to be
515 * page-aligned, so we round the size up for that.
516 */
517 len = page_align(st.st_size);
518 map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
519 /*
520 * Once a file is mapped, you can close the file descriptor. It's a
521 * little odd, but quite useful.
522 */
523 close(ifd);
524 verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
525
526 /* We return the initrd size. */
527 return len;
528}
529/*:*/
530
531/*
532 * Simple routine to roll all the commandline arguments together with spaces
533 * between them.
534 */
535static void concat(char *dst, char *args[])
536{
537 unsigned int i, len = 0;
538
539 for (i = 0; args[i]; i++) {
540 if (i) {
541 strcat(dst+len, " ");
542 len++;
543 }
544 strcpy(dst+len, args[i]);
545 len += strlen(args[i]);
546 }
547 /* In case it's empty. */
548 dst[len] = '\0';
549}
550
551/*L:185
552 * This is where we actually tell the kernel to initialize the Guest. We
553 * saw the arguments it expects when we looked at initialize() in lguest_user.c:
554 * the base of Guest "physical" memory, the top physical page to allow and the
555 * entry point for the Guest.
556 */
557static void tell_kernel(unsigned long start)
558{
559 unsigned long args[] = { LHREQ_INITIALIZE,
560 (unsigned long)guest_base,
561 guest_limit / getpagesize(), start };
562 verbose("Guest: %p - %p (%#lx)\n",
563 guest_base, guest_base + guest_limit, guest_limit);
564 lguest_fd = open_or_die("/dev/lguest", O_RDWR);
565 if (write(lguest_fd, args, sizeof(args)) < 0)
566 err(1, "Writing to /dev/lguest");
567}
568/*:*/
569
570/*L:200
571 * Device Handling.
572 *
573 * When the Guest gives us a buffer, it sends an array of addresses and sizes.
574 * We need to make sure it's not trying to reach into the Launcher itself, so
575 * we have a convenient routine which checks it and exits with an error message
576 * if something funny is going on:
577 */
578static void *_check_pointer(unsigned long addr, unsigned int size,
579 unsigned int line)
580{
581 /*
582 * Check if the requested address and size exceeds the allocated memory,
583 * or addr + size wraps around.
584 */
585 if ((addr + size) > guest_limit || (addr + size) < addr)
586 errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr);
587 /*
588 * We return a pointer for the caller's convenience, now we know it's
589 * safe to use.
590 */
591 return from_guest_phys(addr);
592}
593/* A macro which transparently hands the line number to the real function. */
594#define check_pointer(addr,size) _check_pointer(addr, size, __LINE__)
595
596/*
597 * Each buffer in the virtqueues is actually a chain of descriptors. This
598 * function returns the next descriptor in the chain, or vq->vring.num if we're
599 * at the end.
600 */
601static unsigned next_desc(struct vring_desc *desc,
602 unsigned int i, unsigned int max)
603{
604 unsigned int next;
605
606 /* If this descriptor says it doesn't chain, we're done. */
607 if (!(desc[i].flags & VRING_DESC_F_NEXT))
608 return max;
609
610 /* Check they're not leading us off end of descriptors. */
611 next = desc[i].next;
612 /* Make sure compiler knows to grab that: we don't want it changing! */
613 wmb();
614
615 if (next >= max)
616 errx(1, "Desc next is %u", next);
617
618 return next;
619}
620
621/*
622 * This actually sends the interrupt for this virtqueue, if we've used a
623 * buffer.
624 */
625static void trigger_irq(struct virtqueue *vq)
626{
627 unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
628
629 /* Don't inform them if nothing used. */
630 if (!vq->pending_used)
631 return;
632 vq->pending_used = 0;
633
634 /* If they don't want an interrupt, don't send one... */
635 if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
636 return;
637 }
638
639 /* Send the Guest an interrupt tell them we used something up. */
640 if (write(lguest_fd, buf, sizeof(buf)) != 0)
641 err(1, "Triggering irq %i", vq->config.irq);
642}
643
644/*
645 * This looks in the virtqueue for the first available buffer, and converts
646 * it to an iovec for convenient access. Since descriptors consist of some
647 * number of output then some number of input descriptors, it's actually two
648 * iovecs, but we pack them into one and note how many of each there were.
649 *
650 * This function waits if necessary, and returns the descriptor number found.
651 */
652static unsigned wait_for_vq_desc(struct virtqueue *vq,
653 struct iovec iov[],
654 unsigned int *out_num, unsigned int *in_num)
655{
656 unsigned int i, head, max;
657 struct vring_desc *desc;
658 u16 last_avail = lg_last_avail(vq);
659
660 /* There's nothing available? */
661 while (last_avail == vq->vring.avail->idx) {
662 u64 event;
663
664 /*
665 * Since we're about to sleep, now is a good time to tell the
666 * Guest about what we've used up to now.
667 */
668 trigger_irq(vq);
669
670 /* OK, now we need to know about added descriptors. */
671 vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
672
673 /*
674 * They could have slipped one in as we were doing that: make
675 * sure it's written, then check again.
676 */
677 mb();
678 if (last_avail != vq->vring.avail->idx) {
679 vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
680 break;
681 }
682
683 /* Nothing new? Wait for eventfd to tell us they refilled. */
684 if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
685 errx(1, "Event read failed?");
686
687 /* We don't need to be notified again. */
688 vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
689 }
690
691 /* Check it isn't doing very strange things with descriptor numbers. */
692 if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
693 errx(1, "Guest moved used index from %u to %u",
694 last_avail, vq->vring.avail->idx);
695
696 /*
697 * Grab the next descriptor number they're advertising, and increment
698 * the index we've seen.
699 */
700 head = vq->vring.avail->ring[last_avail % vq->vring.num];
701 lg_last_avail(vq)++;
702
703 /* If their number is silly, that's a fatal mistake. */
704 if (head >= vq->vring.num)
705 errx(1, "Guest says index %u is available", head);
706
707 /* When we start there are none of either input nor output. */
708 *out_num = *in_num = 0;
709
710 max = vq->vring.num;
711 desc = vq->vring.desc;
712 i = head;
713
714 /*
715 * If this is an indirect entry, then this buffer contains a descriptor
716 * table which we handle as if it's any normal descriptor chain.
717 */
718 if (desc[i].flags & VRING_DESC_F_INDIRECT) {
719 if (desc[i].len % sizeof(struct vring_desc))
720 errx(1, "Invalid size for indirect buffer table");
721
722 max = desc[i].len / sizeof(struct vring_desc);
723 desc = check_pointer(desc[i].addr, desc[i].len);
724 i = 0;
725 }
726
727 do {
728 /* Grab the first descriptor, and check it's OK. */
729 iov[*out_num + *in_num].iov_len = desc[i].len;
730 iov[*out_num + *in_num].iov_base
731 = check_pointer(desc[i].addr, desc[i].len);
732 /* If this is an input descriptor, increment that count. */
733 if (desc[i].flags & VRING_DESC_F_WRITE)
734 (*in_num)++;
735 else {
736 /*
737 * If it's an output descriptor, they're all supposed
738 * to come before any input descriptors.
739 */
740 if (*in_num)
741 errx(1, "Descriptor has out after in");
742 (*out_num)++;
743 }
744
745 /* If we've got too many, that implies a descriptor loop. */
746 if (*out_num + *in_num > max)
747 errx(1, "Looped descriptor");
748 } while ((i = next_desc(desc, i, max)) != max);
749
750 return head;
751}
752
753/*
754 * After we've used one of their buffers, we tell the Guest about it. Sometime
755 * later we'll want to send them an interrupt using trigger_irq(); note that
756 * wait_for_vq_desc() does that for us if it has to wait.
757 */
758static void add_used(struct virtqueue *vq, unsigned int head, int len)
759{
760 struct vring_used_elem *used;
761
762 /*
763 * The virtqueue contains a ring of used buffers. Get a pointer to the
764 * next entry in that used ring.
765 */
766 used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
767 used->id = head;
768 used->len = len;
769 /* Make sure buffer is written before we update index. */
770 wmb();
771 vq->vring.used->idx++;
772 vq->pending_used++;
773}
774
775/* And here's the combo meal deal. Supersize me! */
776static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
777{
778 add_used(vq, head, len);
779 trigger_irq(vq);
780}
781
782/*
783 * The Console
784 *
785 * We associate some data with the console for our exit hack.
786 */
787struct console_abort {
788 /* How many times have they hit ^C? */
789 int count;
790 /* When did they start? */
791 struct timeval start;
792};
793
794/* This is the routine which handles console input (ie. stdin). */
795static void console_input(struct virtqueue *vq)
796{
797 int len;
798 unsigned int head, in_num, out_num;
799 struct console_abort *abort = vq->dev->priv;
800 struct iovec iov[vq->vring.num];
801
802 /* Make sure there's a descriptor available. */
803 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
804 if (out_num)
805 errx(1, "Output buffers in console in queue?");
806
807 /* Read into it. This is where we usually wait. */
808 len = readv(STDIN_FILENO, iov, in_num);
809 if (len <= 0) {
810 /* Ran out of input? */
811 warnx("Failed to get console input, ignoring console.");
812 /*
813 * For simplicity, dying threads kill the whole Launcher. So
814 * just nap here.
815 */
816 for (;;)
817 pause();
818 }
819
820 /* Tell the Guest we used a buffer. */
821 add_used_and_trigger(vq, head, len);
822
823 /*
824 * Three ^C within one second? Exit.
825 *
826 * This is such a hack, but works surprisingly well. Each ^C has to
827 * be in a buffer by itself, so they can't be too fast. But we check
828 * that we get three within about a second, so they can't be too
829 * slow.
830 */
831 if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
832 abort->count = 0;
833 return;
834 }
835
836 abort->count++;
837 if (abort->count == 1)
838 gettimeofday(&abort->start, NULL);
839 else if (abort->count == 3) {
840 struct timeval now;
841 gettimeofday(&now, NULL);
842 /* Kill all Launcher processes with SIGINT, like normal ^C */
843 if (now.tv_sec <= abort->start.tv_sec+1)
844 kill(0, SIGINT);
845 abort->count = 0;
846 }
847}
848
849/* This is the routine which handles console output (ie. stdout). */
850static void console_output(struct virtqueue *vq)
851{
852 unsigned int head, out, in;
853 struct iovec iov[vq->vring.num];
854
855 /* We usually wait in here, for the Guest to give us something. */
856 head = wait_for_vq_desc(vq, iov, &out, &in);
857 if (in)
858 errx(1, "Input buffers in console output queue?");
859
860 /* writev can return a partial write, so we loop here. */
861 while (!iov_empty(iov, out)) {
862 int len = writev(STDOUT_FILENO, iov, out);
863 if (len <= 0) {
864 warn("Write to stdout gave %i (%d)", len, errno);
865 break;
866 }
867 iov_consume(iov, out, len);
868 }
869
870 /*
871 * We're finished with that buffer: if we're going to sleep,
872 * wait_for_vq_desc() will prod the Guest with an interrupt.
873 */
874 add_used(vq, head, 0);
875}
876
877/*
878 * The Network
879 *
880 * Handling output for network is also simple: we get all the output buffers
881 * and write them to /dev/net/tun.
882 */
883struct net_info {
884 int tunfd;
885};
886
887static void net_output(struct virtqueue *vq)
888{
889 struct net_info *net_info = vq->dev->priv;
890 unsigned int head, out, in;
891 struct iovec iov[vq->vring.num];
892
893 /* We usually wait in here for the Guest to give us a packet. */
894 head = wait_for_vq_desc(vq, iov, &out, &in);
895 if (in)
896 errx(1, "Input buffers in net output queue?");
897 /*
898 * Send the whole thing through to /dev/net/tun. It expects the exact
899 * same format: what a coincidence!
900 */
901 if (writev(net_info->tunfd, iov, out) < 0)
902 warnx("Write to tun failed (%d)?", errno);
903
904 /*
905 * Done with that one; wait_for_vq_desc() will send the interrupt if
906 * all packets are processed.
907 */
908 add_used(vq, head, 0);
909}
910
911/*
912 * Handling network input is a bit trickier, because I've tried to optimize it.
913 *
914 * First we have a helper routine which tells is if from this file descriptor
915 * (ie. the /dev/net/tun device) will block:
916 */
917static bool will_block(int fd)
918{
919 fd_set fdset;
920 struct timeval zero = { 0, 0 };
921 FD_ZERO(&fdset);
922 FD_SET(fd, &fdset);
923 return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
924}
925
926/*
927 * This handles packets coming in from the tun device to our Guest. Like all
928 * service routines, it gets called again as soon as it returns, so you don't
929 * see a while(1) loop here.
930 */
931static void net_input(struct virtqueue *vq)
932{
933 int len;
934 unsigned int head, out, in;
935 struct iovec iov[vq->vring.num];
936 struct net_info *net_info = vq->dev->priv;
937
938 /*
939 * Get a descriptor to write an incoming packet into. This will also
940 * send an interrupt if they're out of descriptors.
941 */
942 head = wait_for_vq_desc(vq, iov, &out, &in);
943 if (out)
944 errx(1, "Output buffers in net input queue?");
945
946 /*
947 * If it looks like we'll block reading from the tun device, send them
948 * an interrupt.
949 */
950 if (vq->pending_used && will_block(net_info->tunfd))
951 trigger_irq(vq);
952
953 /*
954 * Read in the packet. This is where we normally wait (when there's no
955 * incoming network traffic).
956 */
957 len = readv(net_info->tunfd, iov, in);
958 if (len <= 0)
959 warn("Failed to read from tun (%d).", errno);
960
961 /*
962 * Mark that packet buffer as used, but don't interrupt here. We want
963 * to wait until we've done as much work as we can.
964 */
965 add_used(vq, head, len);
966}
967/*:*/
968
969/* This is the helper to create threads: run the service routine in a loop. */
970static int do_thread(void *_vq)
971{
972 struct virtqueue *vq = _vq;
973
974 for (;;)
975 vq->service(vq);
976 return 0;
977}
978
979/*
980 * When a child dies, we kill our entire process group with SIGTERM. This
981 * also has the side effect that the shell restores the console for us!
982 */
983static void kill_launcher(int signal)
984{
985 kill(0, SIGTERM);
986}
987
988static void reset_device(struct device *dev)
989{
990 struct virtqueue *vq;
991
992 verbose("Resetting device %s\n", dev->name);
993
994 /* Clear any features they've acked. */
995 memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len);
996
997 /* We're going to be explicitly killing threads, so ignore them. */
998 signal(SIGCHLD, SIG_IGN);
999
1000 /* Zero out the virtqueues, get rid of their threads */
1001 for (vq = dev->vq; vq; vq = vq->next) {
1002 if (vq->thread != (pid_t)-1) {
1003 kill(vq->thread, SIGTERM);
1004 waitpid(vq->thread, NULL, 0);
1005 vq->thread = (pid_t)-1;
1006 }
1007 memset(vq->vring.desc, 0,
1008 vring_size(vq->config.num, LGUEST_VRING_ALIGN));
1009 lg_last_avail(vq) = 0;
1010 }
1011 dev->running = false;
1012
1013 /* Now we care if threads die. */
1014 signal(SIGCHLD, (void *)kill_launcher);
1015}
1016
1017/*L:216
1018 * This actually creates the thread which services the virtqueue for a device.
1019 */
1020static void create_thread(struct virtqueue *vq)
1021{
1022 /*
1023 * Create stack for thread. Since the stack grows upwards, we point
1024 * the stack pointer to the end of this region.
1025 */
1026 char *stack = malloc(32768);
1027 unsigned long args[] = { LHREQ_EVENTFD,
1028 vq->config.pfn*getpagesize(), 0 };
1029
1030 /* Create a zero-initialized eventfd. */
1031 vq->eventfd = eventfd(0, 0);
1032 if (vq->eventfd < 0)
1033 err(1, "Creating eventfd");
1034 args[2] = vq->eventfd;
1035
1036 /*
1037 * Attach an eventfd to this virtqueue: it will go off when the Guest
1038 * does an LHCALL_NOTIFY for this vq.
1039 */
1040 if (write(lguest_fd, &args, sizeof(args)) != 0)
1041 err(1, "Attaching eventfd");
1042
1043 /*
1044 * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
1045 * we get a signal if it dies.
1046 */
1047 vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
1048 if (vq->thread == (pid_t)-1)
1049 err(1, "Creating clone");
1050
1051 /* We close our local copy now the child has it. */
1052 close(vq->eventfd);
1053}
1054
1055static void start_device(struct device *dev)
1056{
1057 unsigned int i;
1058 struct virtqueue *vq;
1059
1060 verbose("Device %s OK: offered", dev->name);
1061 for (i = 0; i < dev->feature_len; i++)
1062 verbose(" %02x", get_feature_bits(dev)[i]);
1063 verbose(", accepted");
1064 for (i = 0; i < dev->feature_len; i++)
1065 verbose(" %02x", get_feature_bits(dev)
1066 [dev->feature_len+i]);
1067
1068 for (vq = dev->vq; vq; vq = vq->next) {
1069 if (vq->service)
1070 create_thread(vq);
1071 }
1072 dev->running = true;
1073}
1074
1075static void cleanup_devices(void)
1076{
1077 struct device *dev;
1078
1079 for (dev = devices.dev; dev; dev = dev->next)
1080 reset_device(dev);
1081
1082 /* If we saved off the original terminal settings, restore them now. */
1083 if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
1084 tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
1085}
1086
1087/* When the Guest tells us they updated the status field, we handle it. */
1088static void update_device_status(struct device *dev)
1089{
1090 /* A zero status is a reset, otherwise it's a set of flags. */
1091 if (dev->desc->status == 0)
1092 reset_device(dev);
1093 else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) {
1094 warnx("Device %s configuration FAILED", dev->name);
1095 if (dev->running)
1096 reset_device(dev);
1097 } else {
1098 if (dev->running)
1099 err(1, "Device %s features finalized twice", dev->name);
1100 start_device(dev);
1101 }
1102}
1103
1104/*L:215
1105 * This is the generic routine we call when the Guest uses LHCALL_NOTIFY. In
1106 * particular, it's used to notify us of device status changes during boot.
1107 */
1108static void handle_output(unsigned long addr)
1109{
1110 struct device *i;
1111
1112 /* Check each device. */
1113 for (i = devices.dev; i; i = i->next) {
1114 struct virtqueue *vq;
1115
1116 /*
1117 * Notifications to device descriptors mean they updated the
1118 * device status.
1119 */
1120 if (from_guest_phys(addr) == i->desc) {
1121 update_device_status(i);
1122 return;
1123 }
1124
1125 /* Devices should not be used before features are finalized. */
1126 for (vq = i->vq; vq; vq = vq->next) {
1127 if (addr != vq->config.pfn*getpagesize())
1128 continue;
1129 errx(1, "Notification on %s before setup!", i->name);
1130 }
1131 }
1132
1133 /*
1134 * Early console write is done using notify on a nul-terminated string
1135 * in Guest memory. It's also great for hacking debugging messages
1136 * into a Guest.
1137 */
1138 if (addr >= guest_limit)
1139 errx(1, "Bad NOTIFY %#lx", addr);
1140
1141 write(STDOUT_FILENO, from_guest_phys(addr),
1142 strnlen(from_guest_phys(addr), guest_limit - addr));
1143}
1144
1145/*L:190
1146 * Device Setup
1147 *
1148 * All devices need a descriptor so the Guest knows it exists, and a "struct
1149 * device" so the Launcher can keep track of it. We have common helper
1150 * routines to allocate and manage them.
1151 */
1152
1153/*
1154 * The layout of the device page is a "struct lguest_device_desc" followed by a
1155 * number of virtqueue descriptors, then two sets of feature bits, then an
1156 * array of configuration bytes. This routine returns the configuration
1157 * pointer.
1158 */
1159static u8 *device_config(const struct device *dev)
1160{
1161 return (void *)(dev->desc + 1)
1162 + dev->num_vq * sizeof(struct lguest_vqconfig)
1163 + dev->feature_len * 2;
1164}
1165
1166/*
1167 * This routine allocates a new "struct lguest_device_desc" from descriptor
1168 * table page just above the Guest's normal memory. It returns a pointer to
1169 * that descriptor.
1170 */
1171static struct lguest_device_desc *new_dev_desc(u16 type)
1172{
1173 struct lguest_device_desc d = { .type = type };
1174 void *p;
1175
1176 /* Figure out where the next device config is, based on the last one. */
1177 if (devices.lastdev)
1178 p = device_config(devices.lastdev)
1179 + devices.lastdev->desc->config_len;
1180 else
1181 p = devices.descpage;
1182
1183 /* We only have one page for all the descriptors. */
1184 if (p + sizeof(d) > (void *)devices.descpage + getpagesize())
1185 errx(1, "Too many devices");
1186
1187 /* p might not be aligned, so we memcpy in. */
1188 return memcpy(p, &d, sizeof(d));
1189}
1190
1191/*
1192 * Each device descriptor is followed by the description of its virtqueues. We
1193 * specify how many descriptors the virtqueue is to have.
1194 */
1195static void add_virtqueue(struct device *dev, unsigned int num_descs,
1196 void (*service)(struct virtqueue *))
1197{
1198 unsigned int pages;
1199 struct virtqueue **i, *vq = malloc(sizeof(*vq));
1200 void *p;
1201
1202 /* First we need some memory for this virtqueue. */
1203 pages = (vring_size(num_descs, LGUEST_VRING_ALIGN) + getpagesize() - 1)
1204 / getpagesize();
1205 p = get_pages(pages);
1206
1207 /* Initialize the virtqueue */
1208 vq->next = NULL;
1209 vq->last_avail_idx = 0;
1210 vq->dev = dev;
1211
1212 /*
1213 * This is the routine the service thread will run, and its Process ID
1214 * once it's running.
1215 */
1216 vq->service = service;
1217 vq->thread = (pid_t)-1;
1218
1219 /* Initialize the configuration. */
1220 vq->config.num = num_descs;
1221 vq->config.irq = devices.next_irq++;
1222 vq->config.pfn = to_guest_phys(p) / getpagesize();
1223
1224 /* Initialize the vring. */
1225 vring_init(&vq->vring, num_descs, p, LGUEST_VRING_ALIGN);
1226
1227 /*
1228 * Append virtqueue to this device's descriptor. We use
1229 * device_config() to get the end of the device's current virtqueues;
1230 * we check that we haven't added any config or feature information
1231 * yet, otherwise we'd be overwriting them.
1232 */
1233 assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0);
1234 memcpy(device_config(dev), &vq->config, sizeof(vq->config));
1235 dev->num_vq++;
1236 dev->desc->num_vq++;
1237
1238 verbose("Virtqueue page %#lx\n", to_guest_phys(p));
1239
1240 /*
1241 * Add to tail of list, so dev->vq is first vq, dev->vq->next is
1242 * second.
1243 */
1244 for (i = &dev->vq; *i; i = &(*i)->next);
1245 *i = vq;
1246}
1247
1248/*
1249 * The first half of the feature bitmask is for us to advertise features. The
1250 * second half is for the Guest to accept features.
1251 */
1252static void add_feature(struct device *dev, unsigned bit)
1253{
1254 u8 *features = get_feature_bits(dev);
1255
1256 /* We can't extend the feature bits once we've added config bytes */
1257 if (dev->desc->feature_len <= bit / CHAR_BIT) {
1258 assert(dev->desc->config_len == 0);
1259 dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1;
1260 }
1261
1262 features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT));
1263}
1264
1265/*
1266 * This routine sets the configuration fields for an existing device's
1267 * descriptor. It only works for the last device, but that's OK because that's
1268 * how we use it.
1269 */
1270static void set_config(struct device *dev, unsigned len, const void *conf)
1271{
1272 /* Check we haven't overflowed our single page. */
1273 if (device_config(dev) + len > devices.descpage + getpagesize())
1274 errx(1, "Too many devices");
1275
1276 /* Copy in the config information, and store the length. */
1277 memcpy(device_config(dev), conf, len);
1278 dev->desc->config_len = len;
1279
1280 /* Size must fit in config_len field (8 bits)! */
1281 assert(dev->desc->config_len == len);
1282}
1283
1284/*
1285 * This routine does all the creation and setup of a new device, including
1286 * calling new_dev_desc() to allocate the descriptor and device memory. We
1287 * don't actually start the service threads until later.
1288 *
1289 * See what I mean about userspace being boring?
1290 */
1291static struct device *new_device(const char *name, u16 type)
1292{
1293 struct device *dev = malloc(sizeof(*dev));
1294
1295 /* Now we populate the fields one at a time. */
1296 dev->desc = new_dev_desc(type);
1297 dev->name = name;
1298 dev->vq = NULL;
1299 dev->feature_len = 0;
1300 dev->num_vq = 0;
1301 dev->running = false;
1302
1303 /*
1304 * Append to device list. Prepending to a single-linked list is
1305 * easier, but the user expects the devices to be arranged on the bus
1306 * in command-line order. The first network device on the command line
1307 * is eth0, the first block device /dev/vda, etc.
1308 */
1309 if (devices.lastdev)
1310 devices.lastdev->next = dev;
1311 else
1312 devices.dev = dev;
1313 devices.lastdev = dev;
1314
1315 return dev;
1316}
1317
1318/*
1319 * Our first setup routine is the console. It's a fairly simple device, but
1320 * UNIX tty handling makes it uglier than it could be.
1321 */
1322static void setup_console(void)
1323{
1324 struct device *dev;
1325
1326 /* If we can save the initial standard input settings... */
1327 if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
1328 struct termios term = orig_term;
1329 /*
1330 * Then we turn off echo, line buffering and ^C etc: We want a
1331 * raw input stream to the Guest.
1332 */
1333 term.c_lflag &= ~(ISIG|ICANON|ECHO);
1334 tcsetattr(STDIN_FILENO, TCSANOW, &term);
1335 }
1336
1337 dev = new_device("console", VIRTIO_ID_CONSOLE);
1338
1339 /* We store the console state in dev->priv, and initialize it. */
1340 dev->priv = malloc(sizeof(struct console_abort));
1341 ((struct console_abort *)dev->priv)->count = 0;
1342
1343 /*
1344 * The console needs two virtqueues: the input then the output. When
1345 * they put something the input queue, we make sure we're listening to
1346 * stdin. When they put something in the output queue, we write it to
1347 * stdout.
1348 */
1349 add_virtqueue(dev, VIRTQUEUE_NUM, console_input);
1350 add_virtqueue(dev, VIRTQUEUE_NUM, console_output);
1351
1352 verbose("device %u: console\n", ++devices.device_num);
1353}
1354/*:*/
1355
1356/*M:010
1357 * Inter-guest networking is an interesting area. Simplest is to have a
1358 * --sharenet=<name> option which opens or creates a named pipe. This can be
1359 * used to send packets to another guest in a 1:1 manner.
1360 *
1361 * More sophisticated is to use one of the tools developed for project like UML
1362 * to do networking.
1363 *
1364 * Faster is to do virtio bonding in kernel. Doing this 1:1 would be
1365 * completely generic ("here's my vring, attach to your vring") and would work
1366 * for any traffic. Of course, namespace and permissions issues need to be
1367 * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
1368 * multiple inter-guest channels behind one interface, although it would
1369 * require some manner of hotplugging new virtio channels.
1370 *
1371 * Finally, we could use a virtio network switch in the kernel, ie. vhost.
1372:*/
1373
1374static u32 str2ip(const char *ipaddr)
1375{
1376 unsigned int b[4];
1377
1378 if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
1379 errx(1, "Failed to parse IP address '%s'", ipaddr);
1380 return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
1381}
1382
1383static void str2mac(const char *macaddr, unsigned char mac[6])
1384{
1385 unsigned int m[6];
1386 if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
1387 &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
1388 errx(1, "Failed to parse mac address '%s'", macaddr);
1389 mac[0] = m[0];
1390 mac[1] = m[1];
1391 mac[2] = m[2];
1392 mac[3] = m[3];
1393 mac[4] = m[4];
1394 mac[5] = m[5];
1395}
1396
1397/*
1398 * This code is "adapted" from libbridge: it attaches the Host end of the
1399 * network device to the bridge device specified by the command line.
1400 *
1401 * This is yet another James Morris contribution (I'm an IP-level guy, so I
1402 * dislike bridging), and I just try not to break it.
1403 */
1404static void add_to_bridge(int fd, const char *if_name, const char *br_name)
1405{
1406 int ifidx;
1407 struct ifreq ifr;
1408
1409 if (!*br_name)
1410 errx(1, "must specify bridge name");
1411
1412 ifidx = if_nametoindex(if_name);
1413 if (!ifidx)
1414 errx(1, "interface %s does not exist!", if_name);
1415
1416 strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
1417 ifr.ifr_name[IFNAMSIZ-1] = '\0';
1418 ifr.ifr_ifindex = ifidx;
1419 if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
1420 err(1, "can't add %s to bridge %s", if_name, br_name);
1421}
1422
1423/*
1424 * This sets up the Host end of the network device with an IP address, brings
1425 * it up so packets will flow, the copies the MAC address into the hwaddr
1426 * pointer.
1427 */
1428static void configure_device(int fd, const char *tapif, u32 ipaddr)
1429{
1430 struct ifreq ifr;
1431 struct sockaddr_in sin;
1432
1433 memset(&ifr, 0, sizeof(ifr));
1434 strcpy(ifr.ifr_name, tapif);
1435
1436 /* Don't read these incantations. Just cut & paste them like I did! */
1437 sin.sin_family = AF_INET;
1438 sin.sin_addr.s_addr = htonl(ipaddr);
1439 memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
1440 if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
1441 err(1, "Setting %s interface address", tapif);
1442 ifr.ifr_flags = IFF_UP;
1443 if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
1444 err(1, "Bringing interface %s up", tapif);
1445}
1446
1447static int get_tun_device(char tapif[IFNAMSIZ])
1448{
1449 struct ifreq ifr;
1450 int netfd;
1451
1452 /* Start with this zeroed. Messy but sure. */
1453 memset(&ifr, 0, sizeof(ifr));
1454
1455 /*
1456 * We open the /dev/net/tun device and tell it we want a tap device. A
1457 * tap device is like a tun device, only somehow different. To tell
1458 * the truth, I completely blundered my way through this code, but it
1459 * works now!
1460 */
1461 netfd = open_or_die("/dev/net/tun", O_RDWR);
1462 ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
1463 strcpy(ifr.ifr_name, "tap%d");
1464 if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
1465 err(1, "configuring /dev/net/tun");
1466
1467 if (ioctl(netfd, TUNSETOFFLOAD,
1468 TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
1469 err(1, "Could not set features for tun device");
1470
1471 /*
1472 * We don't need checksums calculated for packets coming in this
1473 * device: trust us!
1474 */
1475 ioctl(netfd, TUNSETNOCSUM, 1);
1476
1477 memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
1478 return netfd;
1479}
1480
1481/*L:195
1482 * Our network is a Host<->Guest network. This can either use bridging or
1483 * routing, but the principle is the same: it uses the "tun" device to inject
1484 * packets into the Host as if they came in from a normal network card. We
1485 * just shunt packets between the Guest and the tun device.
1486 */
1487static void setup_tun_net(char *arg)
1488{
1489 struct device *dev;
1490 struct net_info *net_info = malloc(sizeof(*net_info));
1491 int ipfd;
1492 u32 ip = INADDR_ANY;
1493 bool bridging = false;
1494 char tapif[IFNAMSIZ], *p;
1495 struct virtio_net_config conf;
1496
1497 net_info->tunfd = get_tun_device(tapif);
1498
1499 /* First we create a new network device. */
1500 dev = new_device("net", VIRTIO_ID_NET);
1501 dev->priv = net_info;
1502
1503 /* Network devices need a recv and a send queue, just like console. */
1504 add_virtqueue(dev, VIRTQUEUE_NUM, net_input);
1505 add_virtqueue(dev, VIRTQUEUE_NUM, net_output);
1506
1507 /*
1508 * We need a socket to perform the magic network ioctls to bring up the
1509 * tap interface, connect to the bridge etc. Any socket will do!
1510 */
1511 ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
1512 if (ipfd < 0)
1513 err(1, "opening IP socket");
1514
1515 /* If the command line was --tunnet=bridge:<name> do bridging. */
1516 if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
1517 arg += strlen(BRIDGE_PFX);
1518 bridging = true;
1519 }
1520
1521 /* A mac address may follow the bridge name or IP address */
1522 p = strchr(arg, ':');
1523 if (p) {
1524 str2mac(p+1, conf.mac);
1525 add_feature(dev, VIRTIO_NET_F_MAC);
1526 *p = '\0';
1527 }
1528
1529 /* arg is now either an IP address or a bridge name */
1530 if (bridging)
1531 add_to_bridge(ipfd, tapif, arg);
1532 else
1533 ip = str2ip(arg);
1534
1535 /* Set up the tun device. */
1536 configure_device(ipfd, tapif, ip);
1537
1538 /* Expect Guest to handle everything except UFO */
1539 add_feature(dev, VIRTIO_NET_F_CSUM);
1540 add_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
1541 add_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
1542 add_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
1543 add_feature(dev, VIRTIO_NET_F_GUEST_ECN);
1544 add_feature(dev, VIRTIO_NET_F_HOST_TSO4);
1545 add_feature(dev, VIRTIO_NET_F_HOST_TSO6);
1546 add_feature(dev, VIRTIO_NET_F_HOST_ECN);
1547 /* We handle indirect ring entries */
1548 add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
1549 set_config(dev, sizeof(conf), &conf);
1550
1551 /* We don't need the socket any more; setup is done. */
1552 close(ipfd);
1553
1554 devices.device_num++;
1555
1556 if (bridging)
1557 verbose("device %u: tun %s attached to bridge: %s\n",
1558 devices.device_num, tapif, arg);
1559 else
1560 verbose("device %u: tun %s: %s\n",
1561 devices.device_num, tapif, arg);
1562}
1563/*:*/
1564
1565/* This hangs off device->priv. */
1566struct vblk_info {
1567 /* The size of the file. */
1568 off64_t len;
1569
1570 /* The file descriptor for the file. */
1571 int fd;
1572
1573};
1574
1575/*L:210
1576 * The Disk
1577 *
1578 * The disk only has one virtqueue, so it only has one thread. It is really
1579 * simple: the Guest asks for a block number and we read or write that position
1580 * in the file.
1581 *
1582 * Before we serviced each virtqueue in a separate thread, that was unacceptably
1583 * slow: the Guest waits until the read is finished before running anything
1584 * else, even if it could have been doing useful work.
1585 *
1586 * We could have used async I/O, except it's reputed to suck so hard that
1587 * characters actually go missing from your code when you try to use it.
1588 */
1589static void blk_request(struct virtqueue *vq)
1590{
1591 struct vblk_info *vblk = vq->dev->priv;
1592 unsigned int head, out_num, in_num, wlen;
1593 int ret;
1594 u8 *in;
1595 struct virtio_blk_outhdr *out;
1596 struct iovec iov[vq->vring.num];
1597 off64_t off;
1598
1599 /*
1600 * Get the next request, where we normally wait. It triggers the
1601 * interrupt to acknowledge previously serviced requests (if any).
1602 */
1603 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
1604
1605 /*
1606 * Every block request should contain at least one output buffer
1607 * (detailing the location on disk and the type of request) and one
1608 * input buffer (to hold the result).
1609 */
1610 if (out_num == 0 || in_num == 0)
1611 errx(1, "Bad virtblk cmd %u out=%u in=%u",
1612 head, out_num, in_num);
1613
1614 out = convert(&iov[0], struct virtio_blk_outhdr);
1615 in = convert(&iov[out_num+in_num-1], u8);
1616 /*
1617 * For historical reasons, block operations are expressed in 512 byte
1618 * "sectors".
1619 */
1620 off = out->sector * 512;
1621
1622 /*
1623 * In general the virtio block driver is allowed to try SCSI commands.
1624 * It'd be nice if we supported eject, for example, but we don't.
1625 */
1626 if (out->type & VIRTIO_BLK_T_SCSI_CMD) {
1627 fprintf(stderr, "Scsi commands unsupported\n");
1628 *in = VIRTIO_BLK_S_UNSUPP;
1629 wlen = sizeof(*in);
1630 } else if (out->type & VIRTIO_BLK_T_OUT) {
1631 /*
1632 * Write
1633 *
1634 * Move to the right location in the block file. This can fail
1635 * if they try to write past end.
1636 */
1637 if (lseek64(vblk->fd, off, SEEK_SET) != off)
1638 err(1, "Bad seek to sector %llu", out->sector);
1639
1640 ret = writev(vblk->fd, iov+1, out_num-1);
1641 verbose("WRITE to sector %llu: %i\n", out->sector, ret);
1642
1643 /*
1644 * Grr... Now we know how long the descriptor they sent was, we
1645 * make sure they didn't try to write over the end of the block
1646 * file (possibly extending it).
1647 */
1648 if (ret > 0 && off + ret > vblk->len) {
1649 /* Trim it back to the correct length */
1650 ftruncate64(vblk->fd, vblk->len);
1651 /* Die, bad Guest, die. */
1652 errx(1, "Write past end %llu+%u", off, ret);
1653 }
1654
1655 wlen = sizeof(*in);
1656 *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
1657 } else if (out->type & VIRTIO_BLK_T_FLUSH) {
1658 /* Flush */
1659 ret = fdatasync(vblk->fd);
1660 verbose("FLUSH fdatasync: %i\n", ret);
1661 wlen = sizeof(*in);
1662 *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
1663 } else {
1664 /*
1665 * Read
1666 *
1667 * Move to the right location in the block file. This can fail
1668 * if they try to read past end.
1669 */
1670 if (lseek64(vblk->fd, off, SEEK_SET) != off)
1671 err(1, "Bad seek to sector %llu", out->sector);
1672
1673 ret = readv(vblk->fd, iov+1, in_num-1);
1674 verbose("READ from sector %llu: %i\n", out->sector, ret);
1675 if (ret >= 0) {
1676 wlen = sizeof(*in) + ret;
1677 *in = VIRTIO_BLK_S_OK;
1678 } else {
1679 wlen = sizeof(*in);
1680 *in = VIRTIO_BLK_S_IOERR;
1681 }
1682 }
1683
1684 /* Finished that request. */
1685 add_used(vq, head, wlen);
1686}
1687
1688/*L:198 This actually sets up a virtual block device. */
1689static void setup_block_file(const char *filename)
1690{
1691 struct device *dev;
1692 struct vblk_info *vblk;
1693 struct virtio_blk_config conf;
1694
1695 /* Creat the device. */
1696 dev = new_device("block", VIRTIO_ID_BLOCK);
1697
1698 /* The device has one virtqueue, where the Guest places requests. */
1699 add_virtqueue(dev, VIRTQUEUE_NUM, blk_request);
1700
1701 /* Allocate the room for our own bookkeeping */
1702 vblk = dev->priv = malloc(sizeof(*vblk));
1703
1704 /* First we open the file and store the length. */
1705 vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
1706 vblk->len = lseek64(vblk->fd, 0, SEEK_END);
1707
1708 /* We support FLUSH. */
1709 add_feature(dev, VIRTIO_BLK_F_FLUSH);
1710
1711 /* Tell Guest how many sectors this device has. */
1712 conf.capacity = cpu_to_le64(vblk->len / 512);
1713
1714 /*
1715 * Tell Guest not to put in too many descriptors at once: two are used
1716 * for the in and out elements.
1717 */
1718 add_feature(dev, VIRTIO_BLK_F_SEG_MAX);
1719 conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
1720
1721 /* Don't try to put whole struct: we have 8 bit limit. */
1722 set_config(dev, offsetof(struct virtio_blk_config, geometry), &conf);
1723
1724 verbose("device %u: virtblock %llu sectors\n",
1725 ++devices.device_num, le64_to_cpu(conf.capacity));
1726}
1727
1728/*L:211
1729 * Our random number generator device reads from /dev/random into the Guest's
1730 * input buffers. The usual case is that the Guest doesn't want random numbers
1731 * and so has no buffers although /dev/random is still readable, whereas
1732 * console is the reverse.
1733 *
1734 * The same logic applies, however.
1735 */
1736struct rng_info {
1737 int rfd;
1738};
1739
1740static void rng_input(struct virtqueue *vq)
1741{
1742 int len;
1743 unsigned int head, in_num, out_num, totlen = 0;
1744 struct rng_info *rng_info = vq->dev->priv;
1745 struct iovec iov[vq->vring.num];
1746
1747 /* First we need a buffer from the Guests's virtqueue. */
1748 head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
1749 if (out_num)
1750 errx(1, "Output buffers in rng?");
1751
1752 /*
1753 * Just like the console write, we loop to cover the whole iovec.
1754 * In this case, short reads actually happen quite a bit.
1755 */
1756 while (!iov_empty(iov, in_num)) {
1757 len = readv(rng_info->rfd, iov, in_num);
1758 if (len <= 0)
1759 err(1, "Read from /dev/random gave %i", len);
1760 iov_consume(iov, in_num, len);
1761 totlen += len;
1762 }
1763
1764 /* Tell the Guest about the new input. */
1765 add_used(vq, head, totlen);
1766}
1767
1768/*L:199
1769 * This creates a "hardware" random number device for the Guest.
1770 */
1771static void setup_rng(void)
1772{
1773 struct device *dev;
1774 struct rng_info *rng_info = malloc(sizeof(*rng_info));
1775
1776 /* Our device's privat info simply contains the /dev/random fd. */
1777 rng_info->rfd = open_or_die("/dev/random", O_RDONLY);
1778
1779 /* Create the new device. */
1780 dev = new_device("rng", VIRTIO_ID_RNG);
1781 dev->priv = rng_info;
1782
1783 /* The device has one virtqueue, where the Guest places inbufs. */
1784 add_virtqueue(dev, VIRTQUEUE_NUM, rng_input);
1785
1786 verbose("device %u: rng\n", devices.device_num++);
1787}
1788/* That's the end of device setup. */
1789
1790/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
1791static void __attribute__((noreturn)) restart_guest(void)
1792{
1793 unsigned int i;
1794
1795 /*
1796 * Since we don't track all open fds, we simply close everything beyond
1797 * stderr.
1798 */
1799 for (i = 3; i < FD_SETSIZE; i++)
1800 close(i);
1801
1802 /* Reset all the devices (kills all threads). */
1803 cleanup_devices();
1804
1805 execv(main_args[0], main_args);
1806 err(1, "Could not exec %s", main_args[0]);
1807}
1808
1809/*L:220
1810 * Finally we reach the core of the Launcher which runs the Guest, serves
1811 * its input and output, and finally, lays it to rest.
1812 */
1813static void __attribute__((noreturn)) run_guest(void)
1814{
1815 for (;;) {
1816 unsigned long notify_addr;
1817 int readval;
1818
1819 /* We read from the /dev/lguest device to run the Guest. */
1820 readval = pread(lguest_fd, &notify_addr,
1821 sizeof(notify_addr), cpu_id);
1822
1823 /* One unsigned long means the Guest did HCALL_NOTIFY */
1824 if (readval == sizeof(notify_addr)) {
1825 verbose("Notify on address %#lx\n", notify_addr);
1826 handle_output(notify_addr);
1827 /* ENOENT means the Guest died. Reading tells us why. */
1828 } else if (errno == ENOENT) {
1829 char reason[1024] = { 0 };
1830 pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
1831 errx(1, "%s", reason);
1832 /* ERESTART means that we need to reboot the guest */
1833 } else if (errno == ERESTART) {
1834 restart_guest();
1835 /* Anything else means a bug or incompatible change. */
1836 } else
1837 err(1, "Running guest failed");
1838 }
1839}
1840/*L:240
1841 * This is the end of the Launcher. The good news: we are over halfway
1842 * through! The bad news: the most fiendish part of the code still lies ahead
1843 * of us.
1844 *
1845 * Are you ready? Take a deep breath and join me in the core of the Host, in
1846 * "make Host".
1847:*/
1848
1849static struct option opts[] = {
1850 { "verbose", 0, NULL, 'v' },
1851 { "tunnet", 1, NULL, 't' },
1852 { "block", 1, NULL, 'b' },
1853 { "rng", 0, NULL, 'r' },
1854 { "initrd", 1, NULL, 'i' },
1855 { "username", 1, NULL, 'u' },
1856 { "chroot", 1, NULL, 'c' },
1857 { NULL },
1858};
1859static void usage(void)
1860{
1861 errx(1, "Usage: lguest [--verbose] "
1862 "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
1863 "|--block=<filename>|--initrd=<filename>]...\n"
1864 "<mem-in-mb> vmlinux [args...]");
1865}
1866
1867/*L:105 The main routine is where the real work begins: */
1868int main(int argc, char *argv[])
1869{
1870 /* Memory, code startpoint and size of the (optional) initrd. */
1871 unsigned long mem = 0, start, initrd_size = 0;
1872 /* Two temporaries. */
1873 int i, c;
1874 /* The boot information for the Guest. */
1875 struct boot_params *boot;
1876 /* If they specify an initrd file to load. */
1877 const char *initrd_name = NULL;
1878
1879 /* Password structure for initgroups/setres[gu]id */
1880 struct passwd *user_details = NULL;
1881
1882 /* Directory to chroot to */
1883 char *chroot_path = NULL;
1884
1885 /* Save the args: we "reboot" by execing ourselves again. */
1886 main_args = argv;
1887
1888 /*
1889 * First we initialize the device list. We keep a pointer to the last
1890 * device, and the next interrupt number to use for devices (1:
1891 * remember that 0 is used by the timer).
1892 */
1893 devices.lastdev = NULL;
1894 devices.next_irq = 1;
1895
1896 /* We're CPU 0. In fact, that's the only CPU possible right now. */
1897 cpu_id = 0;
1898
1899 /*
1900 * We need to know how much memory so we can set up the device
1901 * descriptor and memory pages for the devices as we parse the command
1902 * line. So we quickly look through the arguments to find the amount
1903 * of memory now.
1904 */
1905 for (i = 1; i < argc; i++) {
1906 if (argv[i][0] != '-') {
1907 mem = atoi(argv[i]) * 1024 * 1024;
1908 /*
1909 * We start by mapping anonymous pages over all of
1910 * guest-physical memory range. This fills it with 0,
1911 * and ensures that the Guest won't be killed when it
1912 * tries to access it.
1913 */
1914 guest_base = map_zeroed_pages(mem / getpagesize()
1915 + DEVICE_PAGES);
1916 guest_limit = mem;
1917 guest_max = mem + DEVICE_PAGES*getpagesize();
1918 devices.descpage = get_pages(1);
1919 break;
1920 }
1921 }
1922
1923 /* The options are fairly straight-forward */
1924 while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
1925 switch (c) {
1926 case 'v':
1927 verbose = true;
1928 break;
1929 case 't':
1930 setup_tun_net(optarg);
1931 break;
1932 case 'b':
1933 setup_block_file(optarg);
1934 break;
1935 case 'r':
1936 setup_rng();
1937 break;
1938 case 'i':
1939 initrd_name = optarg;
1940 break;
1941 case 'u':
1942 user_details = getpwnam(optarg);
1943 if (!user_details)
1944 err(1, "getpwnam failed, incorrect username?");
1945 break;
1946 case 'c':
1947 chroot_path = optarg;
1948 break;
1949 default:
1950 warnx("Unknown argument %s", argv[optind]);
1951 usage();
1952 }
1953 }
1954 /*
1955 * After the other arguments we expect memory and kernel image name,
1956 * followed by command line arguments for the kernel.
1957 */
1958 if (optind + 2 > argc)
1959 usage();
1960
1961 verbose("Guest base is at %p\n", guest_base);
1962
1963 /* We always have a console device */
1964 setup_console();
1965
1966 /* Now we load the kernel */
1967 start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
1968
1969 /* Boot information is stashed at physical address 0 */
1970 boot = from_guest_phys(0);
1971
1972 /* Map the initrd image if requested (at top of physical memory) */
1973 if (initrd_name) {
1974 initrd_size = load_initrd(initrd_name, mem);
1975 /*
1976 * These are the location in the Linux boot header where the
1977 * start and size of the initrd are expected to be found.
1978 */
1979 boot->hdr.ramdisk_image = mem - initrd_size;
1980 boot->hdr.ramdisk_size = initrd_size;
1981 /* The bootloader type 0xFF means "unknown"; that's OK. */
1982 boot->hdr.type_of_loader = 0xFF;
1983 }
1984
1985 /*
1986 * The Linux boot header contains an "E820" memory map: ours is a
1987 * simple, single region.
1988 */
1989 boot->e820_entries = 1;
1990 boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
1991 /*
1992 * The boot header contains a command line pointer: we put the command
1993 * line after the boot header.
1994 */
1995 boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
1996 /* We use a simple helper to copy the arguments separated by spaces. */
1997 concat((char *)(boot + 1), argv+optind+2);
1998
1999 /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
2000 boot->hdr.kernel_alignment = 0x1000000;
2001
2002 /* Boot protocol version: 2.07 supports the fields for lguest. */
2003 boot->hdr.version = 0x207;
2004
2005 /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
2006 boot->hdr.hardware_subarch = 1;
2007
2008 /* Tell the entry path not to try to reload segment registers. */
2009 boot->hdr.loadflags |= KEEP_SEGMENTS;
2010
2011 /* We tell the kernel to initialize the Guest. */
2012 tell_kernel(start);
2013
2014 /* Ensure that we terminate if a device-servicing child dies. */
2015 signal(SIGCHLD, kill_launcher);
2016
2017 /* If we exit via err(), this kills all the threads, restores tty. */
2018 atexit(cleanup_devices);
2019
2020 /* If requested, chroot to a directory */
2021 if (chroot_path) {
2022 if (chroot(chroot_path) != 0)
2023 err(1, "chroot(\"%s\") failed", chroot_path);
2024
2025 if (chdir("/") != 0)
2026 err(1, "chdir(\"/\") failed");
2027
2028 verbose("chroot done\n");
2029 }
2030
2031 /* If requested, drop privileges */
2032 if (user_details) {
2033 uid_t u;
2034 gid_t g;
2035
2036 u = user_details->pw_uid;
2037 g = user_details->pw_gid;
2038
2039 if (initgroups(user_details->pw_name, g) != 0)
2040 err(1, "initgroups failed");
2041
2042 if (setresgid(g, g, g) != 0)
2043 err(1, "setresgid failed");
2044
2045 if (setresuid(u, u, u) != 0)
2046 err(1, "setresuid failed");
2047
2048 verbose("Dropping privileges completed\n");
2049 }
2050
2051 /* Finally, run the Guest. This doesn't return. */
2052 run_guest();
2053}
2054/*:*/
2055
2056/*M:999
2057 * Mastery is done: you now know everything I do.
2058 *
2059 * But surely you have seen code, features and bugs in your wanderings which
2060 * you now yearn to attack? That is the real game, and I look forward to you
2061 * patching and forking lguest into the Your-Name-Here-visor.
2062 *
2063 * Farewell, and good coding!
2064 * Rusty Russell.
2065 */
diff --git a/Documentation/virtual/lguest/lguest.txt b/Documentation/virtual/lguest/lguest.txt
deleted file mode 100644
index bff0c554485d..000000000000
--- a/Documentation/virtual/lguest/lguest.txt
+++ /dev/null
@@ -1,129 +0,0 @@
1 __
2 (___()'`; Rusty's Remarkably Unreliable Guide to Lguest
3 /, /` - or, A Young Coder's Illustrated Hypervisor
4 \\"--\\ http://lguest.ozlabs.org
5
6Lguest is designed to be a minimal 32-bit x86 hypervisor for the Linux kernel,
7for Linux developers and users to experiment with virtualization with the
8minimum of complexity. Nonetheless, it should have sufficient features to
9make it useful for specific tasks, and, of course, you are encouraged to fork
10and enhance it (see drivers/lguest/README).
11
12Features:
13
14- Kernel module which runs in a normal kernel.
15- Simple I/O model for communication.
16- Simple program to create new guests.
17- Logo contains cute puppies: http://lguest.ozlabs.org
18
19Developer features:
20
21- Fun to hack on.
22- No ABI: being tied to a specific kernel anyway, you can change anything.
23- Many opportunities for improvement or feature implementation.
24
25Running Lguest:
26
27- The easiest way to run lguest is to use same kernel as guest and host.
28 You can configure them differently, but usually it's easiest not to.
29
30 You will need to configure your kernel with the following options:
31
32 "General setup":
33 "Prompt for development and/or incomplete code/drivers" = Y
34 (CONFIG_EXPERIMENTAL=y)
35
36 "Processor type and features":
37 "Paravirtualized guest support" = Y
38 "Lguest guest support" = Y
39 "High Memory Support" = off/4GB
40 "Alignment value to which kernel should be aligned" = 0x100000
41 (CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and
42 CONFIG_PHYSICAL_ALIGN=0x100000)
43
44 "Device Drivers":
45 "Block devices"
46 "Virtio block driver (EXPERIMENTAL)" = M/Y
47 "Network device support"
48 "Universal TUN/TAP device driver support" = M/Y
49 "Virtio network driver (EXPERIMENTAL)" = M/Y
50 (CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m and CONFIG_TUN=m)
51
52 "Virtualization"
53 "Linux hypervisor example code" = M/Y
54 (CONFIG_LGUEST=m)
55
56- A tool called "lguest" is available in this directory: type "make"
57 to build it. If you didn't build your kernel in-tree, use "make
58 O=<builddir>".
59
60- Create or find a root disk image. There are several useful ones
61 around, such as the xm-test tiny root image at
62 http://xm-test.xensource.com/ramdisks/initrd-1.1-i386.img
63
64 For more serious work, I usually use a distribution ISO image and
65 install it under qemu, then make multiple copies:
66
67 dd if=/dev/zero of=rootfile bs=1M count=2048
68 qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d
69
70 Make sure that you install a getty on /dev/hvc0 if you want to log in on the
71 console!
72
73- "modprobe lg" if you built it as a module.
74
75- Run an lguest as root:
76
77 Documentation/virtual/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 \
78 --block=rootfile root=/dev/vda
79
80 Explanation:
81 64: the amount of memory to use, in MB.
82
83 vmlinux: the kernel image found in the top of your build directory. You
84 can also use a standard bzImage.
85
86 --tunnet=192.168.19.1: configures a "tap" device for networking with this
87 IP address.
88
89 --block=rootfile: a file or block device which becomes /dev/vda
90 inside the guest.
91
92 root=/dev/vda: this (and anything else on the command line) are
93 kernel boot parameters.
94
95- Configuring networking. I usually have the host masquerade, using
96 "iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE" and "echo 1 >
97 /proc/sys/net/ipv4/ip_forward". In this example, I would configure
98 eth0 inside the guest at 192.168.19.2.
99
100 Another method is to bridge the tap device to an external interface
101 using --tunnet=bridge:<bridgename>, and perhaps run dhcp on the guest
102 to obtain an IP address. The bridge needs to be configured first:
103 this option simply adds the tap interface to it.
104
105 A simple example on my system:
106
107 ifconfig eth0 0.0.0.0
108 brctl addbr lg0
109 ifconfig lg0 up
110 brctl addif lg0 eth0
111 dhclient lg0
112
113 Then use --tunnet=bridge:lg0 when launching the guest.
114
115 See:
116
117 http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge
118
119 for general information on how to get bridging to work.
120
121- Random number generation. Using the --rng option will provide a
122 /dev/hwrng in the guest that will read from the host's /dev/random.
123 Use this option in conjunction with rng-tools (see ../hw_random.txt)
124 to provide entropy to the guest kernel's /dev/random.
125
126There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest
127
128Good luck!
129Rusty Russell rusty@rustcorp.com.au.
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-22 04:59:15 -0500