diff options
| -rw-r--r-- | Documentation/lguest/Makefile | 27 | ||||
| -rw-r--r-- | Documentation/lguest/lguest.c | 1012 | ||||
| -rw-r--r-- | Documentation/lguest/lguest.txt | 129 |
3 files changed, 1168 insertions, 0 deletions
diff --git a/Documentation/lguest/Makefile b/Documentation/lguest/Makefile new file mode 100644 index 0000000..b9b9427 --- /dev/null +++ b/Documentation/lguest/Makefile @@ -0,0 +1,27 @@ +# This creates the demonstration utility "lguest" which runs a Linux guest. + +# For those people that have a separate object dir, look there for .config +KBUILD_OUTPUT := ../.. +ifdef O + ifeq ("$(origin O)", "command line") + KBUILD_OUTPUT := $(O) + endif +endif +# We rely on CONFIG_PAGE_OFFSET to know where to put lguest binary. +include $(KBUILD_OUTPUT)/.config +LGUEST_GUEST_TOP := ($(CONFIG_PAGE_OFFSET) - 0x08000000) + +CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 \ + -static -DLGUEST_GUEST_TOP="$(LGUEST_GUEST_TOP)" -Wl,-T,lguest.lds +LDLIBS:=-lz + +all: lguest.lds lguest + +# The linker script on x86 is so complex the only way of creating one +# which will link our binary in the right place is to mangle the +# default one. +lguest.lds: + $(LD) --verbose | awk '/^==========/ { PRINT=1; next; } /SIZEOF_HEADERS/ { gsub(/0x[0-9A-F]*/, "$(LGUEST_GUEST_TOP)") } { if (PRINT) print $$0; }' > $@ + +clean: + rm -f lguest.lds lguest diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c new file mode 100644 index 0000000..1432b50 --- /dev/null +++ b/Documentation/lguest/lguest.c @@ -0,0 +1,1012 @@ +/* Simple program to layout "physical" memory for new lguest guest. + * Linked high to avoid likely physical memory. */ +#define _LARGEFILE64_SOURCE +#define _GNU_SOURCE +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <err.h> +#include <stdint.h> +#include <stdlib.h> +#include <elf.h> +#include <sys/mman.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <fcntl.h> +#include <stdbool.h> +#include <errno.h> +#include <ctype.h> +#include <sys/socket.h> +#include <sys/ioctl.h> +#include <sys/time.h> +#include <time.h> +#include <netinet/in.h> +#include <net/if.h> +#include <linux/sockios.h> +#include <linux/if_tun.h> +#include <sys/uio.h> +#include <termios.h> +#include <getopt.h> +#include <zlib.h> +typedef unsigned long long u64; +typedef uint32_t u32; +typedef uint16_t u16; +typedef uint8_t u8; +#include "../../include/linux/lguest_launcher.h" +#include "../../include/asm-i386/e820.h" + +#define PAGE_PRESENT 0x7 /* Present, RW, Execute */ +#define NET_PEERNUM 1 +#define BRIDGE_PFX "bridge:" +#ifndef SIOCBRADDIF +#define SIOCBRADDIF 0x89a2 /* add interface to bridge */ +#endif + +static bool verbose; +#define verbose(args...) \ + do { if (verbose) printf(args); } while(0) +static int waker_fd; + +struct device_list +{ + fd_set infds; + int max_infd; + + struct device *dev; + struct device **lastdev; +}; + +struct device +{ + struct device *next; + struct lguest_device_desc *desc; + void *mem; + + /* Watch this fd if handle_input non-NULL. */ + int fd; + bool (*handle_input)(int fd, struct device *me); + + /* Watch DMA to this key if handle_input non-NULL. */ + unsigned long watch_key; + u32 (*handle_output)(int fd, const struct iovec *iov, + unsigned int num, struct device *me); + + /* Device-specific data. */ + void *priv; +}; + +static int open_or_die(const char *name, int flags) +{ + int fd = open(name, flags); + if (fd < 0) + err(1, "Failed to open %s", name); + return fd; +} + +static void *map_zeroed_pages(unsigned long addr, unsigned int num) +{ + static int fd = -1; + + if (fd == -1) + fd = open_or_die("/dev/zero", O_RDONLY); + + if (mmap((void *)addr, getpagesize() * num, + PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, 0) + != (void *)addr) + err(1, "Mmaping %u pages of /dev/zero @%p", num, (void *)addr); + return (void *)addr; +} + +/* Find magic string marking entry point, return entry point. */ +static unsigned long entry_point(void *start, void *end, + unsigned long page_offset) +{ + void *p; + + for (p = start; p < end; p++) + if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0) + return (long)p + strlen("GenuineLguest") + page_offset; + + err(1, "Is this image a genuine lguest?"); +} + +/* Returns the entry point */ +static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr, + unsigned long *page_offset) +{ + void *addr; + Elf32_Phdr phdr[ehdr->e_phnum]; + unsigned int i; + unsigned long start = -1UL, end = 0; + + /* Sanity checks. */ + if (ehdr->e_type != ET_EXEC + || ehdr->e_machine != EM_386 + || ehdr->e_phentsize != sizeof(Elf32_Phdr) + || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr)) + errx(1, "Malformed elf header"); + + if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0) + err(1, "Seeking to program headers"); + if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr)) + err(1, "Reading program headers"); + + *page_offset = 0; + /* We map the loadable segments at virtual addresses corresponding + * to their physical addresses (our virtual == guest physical). */ + for (i = 0; i < ehdr->e_phnum; i++) { + if (phdr[i].p_type != PT_LOAD) + continue; + + verbose("Section %i: size %i addr %p\n", + i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); + + /* We expect linear address space. */ + if (!*page_offset) + *page_offset = phdr[i].p_vaddr - phdr[i].p_paddr; + else if (*page_offset != phdr[i].p_vaddr - phdr[i].p_paddr) + errx(1, "Page offset of section %i different", i); + + if (phdr[i].p_paddr < start) + start = phdr[i].p_paddr; + if (phdr[i].p_paddr + phdr[i].p_filesz > end) + end = phdr[i].p_paddr + phdr[i].p_filesz; + + /* We map everything private, writable. */ + addr = mmap((void *)phdr[i].p_paddr, + phdr[i].p_filesz, + PROT_READ|PROT_WRITE|PROT_EXEC, + MAP_FIXED|MAP_PRIVATE, + elf_fd, phdr[i].p_offset); + if (addr != (void *)phdr[i].p_paddr) + err(1, "Mmaping vmlinux seg %i gave %p not %p", + i, addr, (void *)phdr[i].p_paddr); + } + + return entry_point((void *)start, (void *)end, *page_offset); +} + +/* This is amazingly reliable. */ +static unsigned long intuit_page_offset(unsigned char *img, unsigned long len) +{ + unsigned int i, possibilities[256] = { 0 }; + + for (i = 0; i + 4 < len; i++) { + /* mov 0xXXXXXXXX,%eax */ + if (img[i] == 0xA1 && ++possibilities[img[i+4]] > 3) + return (unsigned long)img[i+4] << 24; + } + errx(1, "could not determine page offset"); +} + +static unsigned long unpack_bzimage(int fd, unsigned long *page_offset) +{ + gzFile f; + int ret, len = 0; + void *img = (void *)0x100000; + + f = gzdopen(fd, "rb"); + while ((ret = gzread(f, img + len, 65536)) > 0) + len += ret; + if (ret < 0) + err(1, "reading image from bzImage"); + + verbose("Unpacked size %i addr %p\n", len, img); + *page_offset = intuit_page_offset(img, len); + + return entry_point(img, img + len, *page_offset); +} + +static unsigned long load_bzimage(int fd, unsigned long *page_offset) +{ + unsigned char c; + int state = 0; + + /* Ugly brute force search for gzip header. */ + while (read(fd, &c, 1) == 1) { + switch (state) { + case 0: + if (c == 0x1F) + state++; + break; + case 1: + if (c == 0x8B) + state++; + else + state = 0; + break; + case 2 ... 8: + state++; + break; + case 9: + lseek(fd, -10, SEEK_CUR); + if (c != 0x03) /* Compressed under UNIX. */ + state = -1; + else + return unpack_bzimage(fd, page_offset); + } + } + errx(1, "Could not find kernel in bzImage"); +} + +static unsigned long load_kernel(int fd, unsigned long *page_offset) +{ + Elf32_Ehdr hdr; + + if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) + err(1, "Reading kernel"); + + if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0) + return map_elf(fd, &hdr, page_offset); + + return load_bzimage(fd, page_offset); +} + +static inline unsigned long page_align(unsigned long addr) +{ + return ((addr + getpagesize()-1) & ~(getpagesize()-1)); +} + +/* initrd gets loaded at top of memory: return length. */ +static unsigned long load_initrd(const char *name, unsigned long mem) +{ + int ifd; + struct stat st; + unsigned long len; + void *iaddr; + + ifd = open_or_die(name, O_RDONLY); + if (fstat(ifd, &st) < 0) + err(1, "fstat() on initrd '%s'", name); + + len = page_align(st.st_size); + iaddr = mmap((void *)mem - len, st.st_size, + PROT_READ|PROT_EXEC|PROT_WRITE, + MAP_FIXED|MAP_PRIVATE, ifd, 0); + if (iaddr != (void *)mem - len) + err(1, "Mmaping initrd '%s' returned %p not %p", + name, iaddr, (void *)mem - len); + close(ifd); + verbose("mapped initrd %s size=%lu @ %p\n", name, st.st_size, iaddr); + return len; +} + +static unsigned long setup_pagetables(unsigned long mem, + unsigned long initrd_size, + unsigned long page_offset) +{ + u32 *pgdir, *linear; + unsigned int mapped_pages, i, linear_pages; + unsigned int ptes_per_page = getpagesize()/sizeof(u32); + + /* If we can map all of memory above page_offset, we do so. */ + if (mem <= -page_offset) + mapped_pages = mem/getpagesize(); + else + mapped_pages = -page_offset/getpagesize(); + + /* Each linear PTE page can map ptes_per_page pages. */ + linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page; + + /* We lay out top-level then linear mapping immediately below initrd */ + pgdir = (void *)mem - initrd_size - getpagesize(); + linear = (void *)pgdir - linear_pages*getpagesize(); + + for (i = 0; i < mapped_pages; i++) + linear[i] = ((i * getpagesize()) | PAGE_PRESENT); + + /* Now set up pgd so that this memory is at page_offset */ + for (i = 0; i < mapped_pages; i += ptes_per_page) { + pgdir[(i + page_offset/getpagesize())/ptes_per_page] + = (((u32)linear + i*sizeof(u32)) | PAGE_PRESENT); + } + + verbose("Linear mapping of %u pages in %u pte pages at %p\n", + mapped_pages, linear_pages, linear); + + return (unsigned long)pgdir; +} + +static void concat(char *dst, char *args[]) +{ + unsigned int i, len = 0; + + for (i = 0; args[i]; i++) { + strcpy(dst+len, args[i]); + strcat(dst+len, " "); + len += strlen(args[i]) + 1; + } + /* In case it's empty. */ + dst[len] = '\0'; +} + +static int tell_kernel(u32 pgdir, u32 start, u32 page_offset) +{ + u32 args[] = { LHREQ_INITIALIZE, + LGUEST_GUEST_TOP/getpagesize(), /* Just below us */ + pgdir, start, page_offset }; + int fd; + + fd = open_or_die("/dev/lguest", O_RDWR); + if (write(fd, args, sizeof(args)) < 0) + err(1, "Writing to /dev/lguest"); + return fd; +} + +static void set_fd(int fd, struct device_list *devices) +{ + FD_SET(fd, &devices->infds); + if (fd > devices->max_infd) + devices->max_infd = fd; +} + +/* When input arrives, we tell the kernel to kick lguest out with -EAGAIN. */ +static void wake_parent(int pipefd, int lguest_fd, struct device_list *devices) +{ + set_fd(pipefd, devices); + + for (;;) { + fd_set rfds = devices->infds; + u32 args[] = { LHREQ_BREAK, 1 }; + + select(devices->max_infd+1, &rfds, NULL, NULL, NULL); + if (FD_ISSET(pipefd, &rfds)) { + int ignorefd; + if (read(pipefd, &ignorefd, sizeof(ignorefd)) == 0) + exit(0); + FD_CLR(ignorefd, &devices->infds); + } else + write(lguest_fd, args, sizeof(args)); + } +} + +static int setup_waker(int lguest_fd, struct device_list *device_list) +{ + int pipefd[2], child; + + pipe(pipefd); + child = fork(); + if (child == -1) + err(1, "forking"); + + if (child == 0) { + close(pipefd[1]); + wake_parent(pipefd[0], lguest_fd, device_list); + } + close(pipefd[0]); + + return pipefd[1]; +} + +static void *_check_pointer(unsigned long addr, unsigned int size, + unsigned int line) +{ + if (addr >= LGUEST_GUEST_TOP || addr + size >= LGUEST_GUEST_TOP) + errx(1, "%s:%i: Invalid address %li", __FILE__, line, addr); + return (void *)addr; +} +#define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) + +/* Returns pointer to dma->used_len */ +static u32 *dma2iov(unsigned long dma, struct iovec iov[], unsigned *num) +{ + unsigned int i; + struct lguest_dma *udma; + + udma = check_pointer(dma, sizeof(*udma)); + for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) { + if (!udma->len[i]) + break; + + iov[i].iov_base = check_pointer(udma->addr[i], udma->len[i]); + iov[i].iov_len = udma->len[i]; + } + *num = i; + return &udma->used_len; +} + +static u32 *get_dma_buffer(int fd, void *key, + struct iovec iov[], unsigned int *num, u32 *irq) +{ + u32 buf[] = { LHREQ_GETDMA, (u32)key }; + unsigned long udma; + u32 *res; + + udma = write(fd, buf, sizeof(buf)); + if (udma == (unsigned long)-1) + return NULL; + + /* Kernel stashes irq in ->used_len. */ + res = dma2iov(udma, iov, num); + *irq = *res; + return res; +} + +static void trigger_irq(int fd, u32 irq) +{ + u32 buf[] = { LHREQ_IRQ, irq }; + if (write(fd, buf, sizeof(buf)) != 0) + err(1, "Triggering irq %i", irq); +} + +static void discard_iovec(struct iovec *iov, unsigned int *num) +{ + static char discard_buf[1024]; + *num = 1; + iov->iov_base = discard_buf; + iov->iov_len = sizeof(discard_buf); +} + +static struct termios orig_term; +static void restore_term(void) +{ + tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); +} + +struct console_abort +{ + int count; + struct timeval start; +}; + +/* We DMA input to buffer bound at start of console page. */ +static bool handle_console_input(int fd, struct device *dev) +{ + u32 irq = 0, *lenp; + int len; + unsigned int num; + struct iovec iov[LGUEST_MAX_DMA_SECTIONS]; + struct console_abort *abort = dev->priv; + + lenp = get_dma_buffer(fd, dev->mem, iov, &num, &irq); + if (!lenp) { + warn("console: no dma buffer!"); + discard_iovec(iov, &num); + } + + len = readv(dev->fd, iov, num); + if (len <= 0) { + warnx("Failed to get console input, ignoring console."); + len = 0; + } + + if (lenp) { + *lenp = len; + trigger_irq(fd, irq); + } + + /* Three ^C within one second? Exit. */ + if (len == 1 && ((char *)iov[0].iov_base)[0] == 3) { + if (!abort->count++) + gettimeofday(&abort->start, NULL); + else if (abort->count == 3) { + struct timeval now; + gettimeofday(&now, NULL); + if (now.tv_sec <= abort->start.tv_sec+1) { + /* Make sure waker is not blocked in BREAK */ + u32 args[] = { LHREQ_BREAK, 0 }; + close(waker_fd); + write(fd, args, sizeof(args)); + exit(2); + } + abort->count = 0; + } + } else + abort->count = 0; + + if (!len) { + restore_term(); + return false; + } + return true; +} + +static u32 handle_console_output(int fd, const struct iovec *iov, + unsigned num, struct device*dev) +{ + return writev(STDOUT_FILENO, iov, num); +} + +static u32 handle_tun_output(int fd, const struct iovec *iov, + unsigned num, struct device *dev) +{ + /* Now we've seen output, we should warn if we can't get buffers. */ + *(bool *)dev->priv = true; + return writev(dev->fd, iov, num); +} + +static unsigned long peer_offset(unsigned int peernum) +{ + return 4 * peernum; +} + +static bool handle_tun_input(int fd, struct device *dev) +{ + u32 irq = 0, *lenp; + int len; + unsigned num; + struct iovec iov[LGUEST_MAX_DMA_SECTIONS]; + + lenp = get_dma_buffer(fd, dev->mem+peer_offset(NET_PEERNUM), iov, &num, + &irq); + if (!lenp) { + if (*(bool *)dev->priv) + warn("network: no dma buffer!"); + discard_iovec(iov, &num); + } + + len = readv(dev->fd, iov, num); + if (len <= 0) + err(1, "reading network"); + if (lenp) { + *lenp = len; + trigger_irq(fd, irq); + } + verbose("tun input packet len %i [%02x %02x] (%s)\n", len, + ((u8 *)iov[0].iov_base)[0], ((u8 *)iov[0].iov_base)[1], + lenp ? "sent" : "discarded"); + return true; +} + +static u32 handle_block_output(int fd, const struct iovec *iov, + unsigned num, struct device *dev) +{ + struct lguest_block_page *p = dev->mem; + u32 irq, *lenp; + unsigned int len, reply_num; + struct iovec reply[LGUEST_MAX_DMA_SECTIONS]; + off64_t device_len, off = (off64_t)p->sector * 512; + + device_len = *(off64_t *)dev->priv; + + if (off >= device_len) + err(1, "Bad offset %llu vs %llu", off, device_len); + if (lseek64(dev->fd, off, SEEK_SET) != off) + err(1, "Bad seek to sector %i", p->sector); + + verbose("Block: %s at offset %llu\n", p->type ? "WRITE" : "READ", off); + + lenp = get_dma_buffer(fd, dev->mem, reply, &reply_num, &irq); + if (!lenp) + err(1, "Block request didn't give us a dma buffer"); + + if (p->type) { + len = writev(dev->fd, iov, num); + if (off + len > device_len) { + ftruncate(dev->fd, device_len); + errx(1, "Write past end %llu+%u", off, len); + } + *lenp = 0; + } else { + len = readv(dev->fd, reply, reply_num); + *lenp = len; + } + + p->result = 1 + (p->bytes != len); + trigger_irq(fd, irq); + return 0; +} + +static void handle_output(int fd, unsigned long dma, unsigned long key, + struct device_list *devices) +{ + struct device *i; + u32 *lenp; + struct iovec iov[LGUEST_MAX_DMA_SECTIONS]; + unsigned num = 0; + + lenp = dma2iov(dma, iov, &num); + for (i = devices->dev; i; i = i->next) { + if (i->handle_output && key == i->watch_key) { + *lenp = i->handle_output(fd, iov, num, i); + return; + } + } + warnx("Pending dma %p, key %p", (void *)dma, (void *)key); +} + +static void handle_input(int fd, struct device_list *devices) +{ + struct timeval poll = { .tv_sec = 0, .tv_usec = 0 }; + + for (;;) { + struct device *i; + fd_set fds = devices->infds; + + if (select(devices->max_infd+1, &fds, NULL, NULL, &poll) == 0) + break; + + for (i = devices->dev; i; i = i->next) { + if (i->handle_input && FD_ISSET(i->fd, &fds)) { + if (!i->handle_input(fd, i)) { + FD_CLR(i->fd, &devices->infds); + /* Tell waker to ignore it too... */ + write(waker_fd, &i->fd, sizeof(i->fd)); + } + } + } + } +} + +static struct lguest_device_desc *new_dev_desc(u16 type, u16 features, + u16 num_pages) +{ + static unsigned long top = LGUEST_GUEST_TOP; + struct lguest_device_desc *desc; + + desc = malloc(sizeof(*desc)); + desc->type = type; + desc->num_pages = num_pages; + desc->features = features; + desc->status = 0; + if (num_pages) { + top -= num_pages*getpagesize(); + map_zeroed_pages(top, num_pages); + desc->pfn = top / getpagesize(); + } else + desc->pfn = 0; + return desc; +} + +static struct device *new_device(struct device_list *devices, + u16 type, u16 num_pages, u16 features, + int fd, + bool (*handle_input)(int, struct device *), + unsigned long watch_off, + u32 (*handle_output)(int, + const struct iovec *, + unsigned, + struct device *)) +{ + struct device *dev = malloc(sizeof(*dev)); + + /* Append to device list. */ + *devices->lastdev = dev; + dev->next = NULL; + devices->lastdev = &dev->next; + + dev->fd = fd; + if (handle_input) + set_fd(dev->fd, devices); + dev->desc = new_dev_desc(type, features, num_pages); + dev->mem = (void *)(dev->desc->pfn * getpagesize()); + dev->handle_input = handle_input; + dev->watch_key = (unsigned long)dev->mem + watch_off; + dev->handle_output = handle_output; + return dev; +} + +static void setup_console(struct device_list *devices) +{ + struct device *dev; + + if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { + struct termios term = orig_term; + term.c_lflag &= ~(ISIG|ICANON|ECHO); + tcsetattr(STDIN_FILENO, TCSANOW, &term); + atexit(restore_term); + } + + /* We don't currently require a page for the console. */ + dev = new_device(devices, LGUEST_DEVICE_T_CONSOLE, 0, 0, + STDIN_FILENO, handle_console_input, + LGUEST_CONSOLE_DMA_KEY, handle_console_output); + dev->priv = malloc(sizeof(struct console_abort)); + ((struct console_abort *)dev->priv)->count = 0; + verbose("device %p: console\n", + (void *)(dev->desc->pfn * getpagesize())); +} + +static void setup_block_file(const char *filename, struct device_list *devices) +{ + int fd; + struct device *dev; + off64_t *device_len; + struct lguest_block_page *p; + + fd = open_or_die(filename, O_RDWR|O_LARGEFILE|O_DIRECT); + dev = new_device(devices, LGUEST_DEVICE_T_BLOCK, 1, + LGUEST_DEVICE_F_RANDOMNESS, + fd, NULL, 0, handle_block_output); + device_len = dev->priv = malloc(sizeof(*device_len)); + *device_len = lseek64(fd, 0, SEEK_END); + p = dev->mem; + + p->num_sectors = *device_len/512; + verbose("device %p: block %i sectors\n", + (void *)(dev->desc->pfn * getpagesize()), p->num_sectors); +} + +/* We use fnctl locks to reserve network slots (autocleanup!) */ +static unsigned int find_slot(int netfd, const char *filename) +{ + struct flock fl; + + fl.l_type = F_WRLCK; + fl.l_whence = SEEK_SET; + fl.l_len = 1; + for (fl.l_start = 0; + fl.l_start < getpagesize()/sizeof(struct lguest_net); + fl.l_start++) { + if (fcntl(netfd, F_SETLK, &fl) == 0) + return fl.l_start; + } + errx(1, "No free slots in network file %s", filename); +} + +static void setup_net_file(const char *filename, + struct device_list *devices) +{ + int netfd; + struct device *dev; + + netfd = open(filename, O_RDWR, 0); + if (netfd < 0) { + if (errno == ENOENT) { + netfd = open(filename, O_RDWR|O_CREAT, 0600); + if (netfd >= 0) { + char page[getpagesize()]; + memset(page, 0, sizeof(page)); + write(netfd, page, sizeof(page)); + } + } + if (netfd < 0) + err(1, "cannot open net file '%s'", filename); + } + + dev = new_device(devices, LGUEST_DEVICE_T_NET, 1, + find_slot(netfd, filename)|LGUEST_NET_F_NOCSUM, + -1, NULL, 0, NULL); + + /* We overwrite the /dev/zero mapping with the actual file. */ + if (mmap(dev->mem, getpagesize(), PROT_READ|PROT_WRITE, + MAP_FIXED|MAP_SHARED, netfd, 0) != dev->mem) + err(1, "could not mmap '%s'", filename); + verbose("device %p: shared net %s, peer %i\n", + (void *)(dev->desc->pfn * getpagesize()), filename, + dev->desc->features & ~LGUEST_NET_F_NOCSUM); +} + +static u32 str2ip(const char *ipaddr) +{ + unsigned int byte[4]; + + sscanf(ipaddr, "%u.%u.%u.%u", &byte[0], &byte[1], &byte[2], &byte[3]); + return (byte[0] << 24) | (byte[1] << 16) | (byte[2] << 8) | byte[3]; +} + +/* adapted from libbridge */ +static void add_to_bridge(int fd, const char *if_name, const char *br_name) +{ + int ifidx; + struct ifreq ifr; + + if (!*br_name) + errx(1, "must specify bridge name"); + + ifidx = if_nametoindex(if_name); + if (!ifidx) + errx(1, "interface %s does not exist!", if_name); + + strncpy(ifr.ifr_name, br_name, IFNAMSIZ); + ifr.ifr_ifindex = ifidx; + if (ioctl(fd, SIOCBRADDIF, &ifr) < 0) + err(1, "can't add %s to bridge %s", if_name, br_name); +} + +static void configure_device(int fd, const char *devname, u32 ipaddr, + unsigned char hwaddr[6]) +{ + struct ifreq ifr; + struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr; + + memset(&ifr, 0, sizeof(ifr)); + strcpy(ifr.ifr_name, devname); + sin->sin_family = AF_INET; + sin->sin_addr.s_addr = htonl(ipaddr); + if (ioctl(fd, SIOCSIFADDR, &ifr) != 0) + err(1, "Setting %s interface address", devname); + ifr.ifr_flags = IFF_UP; + if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0) + err(1, "Bringing interface %s up", devname); + + if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0) + err(1, "getting hw address for %s", devname); + + memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6); +} + +static void setup_tun_net(const char *arg, struct device_list *devices) +{ + struct device *dev; + struct ifreq ifr; + int netfd, ipfd; + u32 ip; + const char *br_name = NULL; + + netfd = open_or_die("/dev/net/tun", O_RDWR); + memset(&ifr, 0, sizeof(ifr)); + ifr.ifr_flags = IFF_TAP | IFF_NO_PI; + strcpy(ifr.ifr_name, "tap%d"); + if (ioctl(netfd, TUNSETIFF, &ifr) != 0) + err(1, "configuring /dev/net/tun"); + ioctl(netfd, TUNSETNOCSUM, 1); + + /* You will be peer 1: we should create enough jitter to randomize */ + dev = new_device(devices, LGUEST_DEVICE_T_NET, 1, + NET_PEERNUM|LGUEST_DEVICE_F_RANDOMNESS, netfd, + handle_tun_input, peer_offset(0), handle_tun_output); + dev->priv = malloc(sizeof(bool)); + *(bool *)dev->priv = false; + + ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); + if (ipfd < 0) + err(1, "opening IP socket"); + + if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) { + ip = INADDR_ANY; + br_name = arg + strlen(BRIDGE_PFX); + add_to_bridge(ipfd, ifr.ifr_name, br_name); + } else + ip = str2ip(arg); + + /* We are peer 0, ie. first slot. */ + configure_device(ipfd, ifr.ifr_name, ip, dev->mem); + + /* Set "promisc" bit: we want every single packet. */ + *((u8 *)dev->mem) |= 0x1; + + close(ipfd); + + verbose("device %p: tun net %u.%u.%u.%u\n", + (void *)(dev->desc->pfn * getpagesize()), + (u8)(ip>>24), (u8)(ip>>16), (u8)(ip>>8), (u8)ip); + if (br_name) + verbose("attached to bridge: %s\n", br_name); +} + +/* Now we know how much memory we have, we copy in device descriptors */ +static void map_device_descriptors(struct device_list *devs, unsigned long mem) +{ + struct device *i; + unsigned int num; + struct lguest_device_desc *descs; + + /* Device descriptor array sits just above top of normal memory */ + descs = map_zeroed_pages(mem, 1); + + for (i = devs->dev, num = 0; i; i = i->next, num++) { + if (num == LGUEST_MAX_DEVICES) + errx(1, "too many devices"); + verbose("Device %i: %s\n", num, + i->desc->type == LGUEST_DEVICE_T_NET ? "net" + : i->desc->type == LGUEST_DEVICE_T_CONSOLE ? "console" + : i->desc->type == LGUEST_DEVICE_T_BLOCK ? "block" + : "unknown"); + descs[num] = *i->desc; + free(i->desc); + i->desc = &descs[num]; + } +} + +static void __attribute__((noreturn)) +run_guest(int lguest_fd, struct device_list *device_list) +{ + for (;;) { + u32 args[] = { LHREQ_BREAK, 0 }; + unsigned long arr[2]; + int readval; + + /* We read from the /dev/lguest device to run the Guest. */ + readval = read(lguest_fd, arr, sizeof(arr)); + + if (readval == sizeof(arr)) { + handle_output(lguest_fd, arr[0], arr[1], device_list); + continue; + } else if (errno == ENOENT) { + char reason[1024] = { 0 }; + read(lguest_fd, reason, sizeof(reason)-1); + errx(1, "%s", reason); + } else if (errno != EAGAIN) + err(1, "Running guest failed"); + handle_input(lguest_fd, device_list); + if (write(lguest_fd, args, sizeof(args)) < 0) + err(1, "Resetting break"); + } +} + +static struct option opts[] = { + { "verbose", 0, NULL, 'v' }, + { "sharenet", 1, NULL, 's' }, + { "tunnet", 1, NULL, 't' }, + { "block", 1, NULL, 'b' }, + { "initrd", 1, NULL, 'i' }, + { NULL }, +}; +static void usage(void) +{ + errx(1, "Usage: lguest [--verbose] " + "[--sharenet=<filename>|--tunnet=(<ipaddr>|bridge:<bridgename>)\n" + "|--block=<filename>|--initrd=<filename>]...\n" + "<mem-in-mb> vmlinux [args...]"); +} + +int main(int argc, char *argv[]) +{ + unsigned long mem, pgdir, start, page_offset, initrd_size = 0; + int c, lguest_fd; + struct device_list device_list; + void *boot = (void *)0; + const char *initrd_name = NULL; + + device_list.max_infd = -1; + device_list.dev = NULL; + device_list.lastdev = &device_list.dev; + FD_ZERO(&device_list.infds); + + while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) { + switch (c) { + case 'v': + verbose = true; + break; + case 's': + setup_net_file(optarg, &device_list); + break; + case 't': + setup_tun_net(optarg, &device_list); + break; + case 'b': + setup_block_file(optarg, &device_list); + break; + case 'i': + initrd_name = optarg; + break; + default: + warnx("Unknown argument %s", argv[optind]); + usage(); + } + } + if (optind + 2 > argc) + usage(); + + /* We need a console device */ + setup_console(&device_list); + + /* First we map /dev/zero over all of guest-physical memory. */ + mem = atoi(argv[optind]) * 1024 * 1024; + map_zeroed_pages(0, mem / getpagesize()); + + /* Now we load the kernel */ + start = load_kernel(open_or_die(argv[optind+1], O_RDONLY), + &page_offset); + + /* Write the device descriptors into memory. */ + map_device_descriptors(&device_list, mem); + + /* Map the initrd image if requested */ + if (initrd_name) { + initrd_size = load_initrd(initrd_name, mem); + *(unsigned long *)(boot+0x218) = mem - initrd_size; + *(unsigned long *)(boot+0x21c) = initrd_size; + *(unsigned char *)(boot+0x210) = 0xFF; + } + + /* Set up the initial linar pagetables. */ + pgdir = setup_pagetables(mem, initrd_size, page_offset); + + /* E820 memory map: ours is a simple, single region. */ + *(char*)(boot+E820NR) = 1; + *((struct e820entry *)(boot+E820MAP)) + = ((struct e820entry) { 0, mem, E820_RAM }); + /* Command line pointer and command line (at 4096) */ + *(void **)(boot + 0x228) = boot + 4096; + concat(boot + 4096, argv+optind+2); + /* Paravirt type: 1 == lguest */ + *(int *)(boot + 0x23c) = 1; + + lguest_fd = tell_kernel(pgdir, start, page_offset); + waker_fd = setup_waker(lguest_fd, &device_list); + + run_guest(lguest_fd, &device_list); +} diff --git a/Documentation/lguest/lguest.txt b/Documentation/lguest/lguest.txt new file mode 100644 index 0000000..821617b --- /dev/null +++ b/Documentation/lguest/lguest.txt @@ -0,0 +1,129 @@ +Rusty's Remarkably Unreliable Guide to Lguest + - or, A Young Coder's Illustrated Hypervisor +http://lguest.ozlabs.org + +Lguest is designed to be a minimal hypervisor for the Linux kernel, for +Linux developers and users to experiment with virtualization with the +minimum of complexity. Nonetheless, it should have sufficient +features to make it useful for specific tasks, and, of course, you are +encouraged to fork and enhance it. + +Features: + +- Kernel module which runs in a normal kernel. +- Simple I/O model for communication. +- Simple program to create new guests. +- Logo contains cute puppies: http://lguest.ozlabs.org + +Developer features: + +- Fun to hack on. +- No ABI: being tied to a specific kernel anyway, you can change anything. +- Many opportunities for improvement or feature implementation. + +Running Lguest: + +- Lguest runs the same kernel as guest and host. You can configure + them differently, but usually it's easiest not to. + + You will need to configure your kernel with the following options: + + CONFIG_HIGHMEM64G=n ("High Memory Support" "64GB")[1] + CONFIG_TUN=y/m ("Universal TUN/TAP device driver support") + CONFIG_EXPERIMENTAL=y ("Prompt for development and/or incomplete code/drivers") + CONFIG_PARAVIRT=y ("Paravirtualization support (EXPERIMENTAL)") + CONFIG_LGUEST=y/m ("Linux hypervisor example code") + + and I recommend: + CONFIG_HZ=100 ("Timer frequency")[2] + +- A tool called "lguest" is available in this directory: type "make" + to build it. If you didn't build your kernel in-tree, use "make + O=<builddir>". + +- Create or find a root disk image. There are several useful ones + around, such as the xm-test tiny root image at + http://xm-test.xensource.com/ramdisks/initrd-1.1-i386.img + + For more serious work, I usually use a distribution ISO image and + install it under qemu, then make multiple copies: + + dd if=/dev/zero of=rootfile bs=1M count=2048 + qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d + +- "modprobe lg" if you built it as a module. + +- Run an lguest as root: + + Documentation/lguest/lguest 64m vmlinux --tunnet=192.168.19.1 --block=rootfile root=/dev/lgba + + Explanation: + 64m: the amount of memory to use. + + vmlinux: the kernel image found in the top of your build directory. You + can also use a standard bzImage. + + --tunnet=192.168.19.1: configures a "tap" device for networking with this + IP address. + + --block=rootfile: a file or block device which becomes /dev/lgba + inside the guest. + + root=/dev/lgba: this (and anything else on the command line) are + kernel boot parameters. + +- Configuring networking. I usually have the host masquerade, using + "iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE" and "echo 1 > + /proc/sys/net/ipv4/ip_forward". In this example, I would configure + eth0 inside the guest at 192.168.19.2. + + Another method is to bridge the tap device to an external interface + using --tunnet=bridge:<bridgename>, and perhaps run dhcp on the guest + to obtain an IP address. The bridge needs to be configured first: + this option simply adds the tap interface to it. + + A simple example on my system: + + ifconfig eth0 0.0.0.0 + brctl addbr lg0 + ifconfig lg0 up + brctl addif lg0 eth0 + dhclient lg0 + + Then use --tunnet=bridge:lg0 when launching the guest. + + See http://linux-net.osdl.org/index.php/Bridge for general information + on how to get bridging working. + +- You can also create an inter-guest network using + "--sharenet=<filename>": any two guests using the same file are on + the same network. This file is created if it does not exist. + +Lguest I/O model: + +Lguest uses a simplified DMA model plus shared memory for I/O. Guests +can communicate with each other if they share underlying memory +(usually by the lguest program mmaping the same file), but they can +use any non-shared memory to communicate with the lguest process. + +Guests can register DMA buffers at any key (must be a valid physical +address) using the LHCALL_BIND_DMA(key, dmabufs, num<<8|irq) +hypercall. "dmabufs" is the physical address of an array of "num" +"struct lguest_dma": each contains a used_len, and an array of +physical addresses and lengths. When a transfer occurs, the +"used_len" field of one of the buffers which has used_len 0 will be +set to the length transferred and the irq will fire. + +Using an irq value of 0 unbinds the dma buffers. + +To send DMA, the LHCALL_SEND_DMA(key, dma_physaddr) hypercall is used, +and the bytes used is written to the used_len field. This can be 0 if +noone else has bound a DMA buffer to that key or some other error. +DMA buffers bound by the same guest are ignored. + +Cheers! +Rusty Russell rusty@rustcorp.com.au. + +[1] These are on various places on the TODO list, waiting for you to + get annoyed enough at the limitation to fix it. +[2] Lguest is not yet tickless when idle. See [1]. |