| /*P:100 This is the Launcher code, a simple program which lays out the |
| * "physical" memory for the new Guest by mapping the kernel image and the |
| * virtual devices, then reads repeatedly from /dev/lguest to run the Guest. |
| :*/ |
| #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/param.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> |
| #include <assert.h> |
| #include <sched.h> |
| #include "linux/lguest_launcher.h" |
| #include "linux/virtio_config.h" |
| #include "linux/virtio_net.h" |
| #include "linux/virtio_blk.h" |
| #include "linux/virtio_console.h" |
| #include "linux/virtio_ring.h" |
| #include "asm-x86/bootparam.h" |
| /*L:110 We can ignore the 38 include files we need for this program, but I do |
| * want to draw attention to the use of kernel-style types. |
| * |
| * As Linus said, "C is a Spartan language, and so should your naming be." I |
| * like these abbreviations, so we define them here. Note that u64 is always |
| * unsigned long long, which works on all Linux systems: this means that we can |
| * use %llu in printf for any u64. */ |
| typedef unsigned long long u64; |
| typedef uint32_t u32; |
| typedef uint16_t u16; |
| typedef uint8_t u8; |
| /*:*/ |
| |
| #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 |
| /* We can have up to 256 pages for devices. */ |
| #define DEVICE_PAGES 256 |
| /* This fits nicely in a single 4096-byte page. */ |
| #define VIRTQUEUE_NUM 127 |
| |
| /*L:120 verbose is both a global flag and a macro. The C preprocessor allows |
| * this, and although I wouldn't recommend it, it works quite nicely here. */ |
| static bool verbose; |
| #define verbose(args...) \ |
| do { if (verbose) printf(args); } while(0) |
| /*:*/ |
| |
| /* The pipe to send commands to the waker process */ |
| static int waker_fd; |
| /* The pointer to the start of guest memory. */ |
| static void *guest_base; |
| /* The maximum guest physical address allowed, and maximum possible. */ |
| static unsigned long guest_limit, guest_max; |
| |
| /* This is our list of devices. */ |
| struct device_list |
| { |
| /* Summary information about the devices in our list: ready to pass to |
| * select() to ask which need servicing.*/ |
| fd_set infds; |
| int max_infd; |
| |
| /* Counter to assign interrupt numbers. */ |
| unsigned int next_irq; |
| |
| /* Counter to print out convenient device numbers. */ |
| unsigned int device_num; |
| |
| /* The descriptor page for the devices. */ |
| u8 *descpage; |
| |
| /* The tail of the last descriptor. */ |
| unsigned int desc_used; |
| |
| /* A single linked list of devices. */ |
| struct device *dev; |
| /* ... And an end pointer so we can easily append new devices */ |
| struct device **lastdev; |
| }; |
| |
| /* The list of Guest devices, based on command line arguments. */ |
| static struct device_list devices; |
| |
| /* The device structure describes a single device. */ |
| struct device |
| { |
| /* The linked-list pointer. */ |
| struct device *next; |
| |
| /* The this device's descriptor, as mapped into the Guest. */ |
| struct lguest_device_desc *desc; |
| |
| /* The name of this device, for --verbose. */ |
| const char *name; |
| |
| /* If handle_input is set, it wants to be called when this file |
| * descriptor is ready. */ |
| int fd; |
| bool (*handle_input)(int fd, struct device *me); |
| |
| /* Any queues attached to this device */ |
| struct virtqueue *vq; |
| |
| /* Device-specific data. */ |
| void *priv; |
| }; |
| |
| /* The virtqueue structure describes a queue attached to a device. */ |
| struct virtqueue |
| { |
| struct virtqueue *next; |
| |
| /* Which device owns me. */ |
| struct device *dev; |
| |
| /* The configuration for this queue. */ |
| struct lguest_vqconfig config; |
| |
| /* The actual ring of buffers. */ |
| struct vring vring; |
| |
| /* Last available index we saw. */ |
| u16 last_avail_idx; |
| |
| /* The routine to call when the Guest pings us. */ |
| void (*handle_output)(int fd, struct virtqueue *me); |
| }; |
| |
| /* Since guest is UP and we don't run at the same time, we don't need barriers. |
| * But I include them in the code in case others copy it. */ |
| #define wmb() |
| |
| /* Convert an iovec element to the given type. |
| * |
| * This is a fairly ugly trick: we need to know the size of the type and |
| * alignment requirement to check the pointer is kosher. It's also nice to |
| * have the name of the type in case we report failure. |
| * |
| * Typing those three things all the time is cumbersome and error prone, so we |
| * have a macro which sets them all up and passes to the real function. */ |
| #define convert(iov, type) \ |
| ((type *)_convert((iov), sizeof(type), __alignof__(type), #type)) |
| |
| static void *_convert(struct iovec *iov, size_t size, size_t align, |
| const char *name) |
| { |
| if (iov->iov_len != size) |
| errx(1, "Bad iovec size %zu for %s", iov->iov_len, name); |
| if ((unsigned long)iov->iov_base % align != 0) |
| errx(1, "Bad alignment %p for %s", iov->iov_base, name); |
| return iov->iov_base; |
| } |
| |
| /* The virtio configuration space is defined to be little-endian. x86 is |
| * little-endian too, but it's nice to be explicit so we have these helpers. */ |
| #define cpu_to_le16(v16) (v16) |
| #define cpu_to_le32(v32) (v32) |
| #define cpu_to_le64(v64) (v64) |
| #define le16_to_cpu(v16) (v16) |
| #define le32_to_cpu(v32) (v32) |
| #define le64_to_cpu(v32) (v64) |
| |
| /*L:100 The Launcher code itself takes us out into userspace, that scary place |
| * where pointers run wild and free! Unfortunately, like most userspace |
| * programs, it's quite boring (which is why everyone likes to hack on the |
| * kernel!). Perhaps if you make up an Lguest Drinking Game at this point, it |
| * will get you through this section. Or, maybe not. |
| * |
| * The Launcher sets up a big chunk of memory to be the Guest's "physical" |
| * memory and stores it in "guest_base". In other words, Guest physical == |
| * Launcher virtual with an offset. |
| * |
| * This can be tough to get your head around, but usually it just means that we |
| * use these trivial conversion functions when the Guest gives us it's |
| * "physical" addresses: */ |
| static void *from_guest_phys(unsigned long addr) |
| { |
| return guest_base + addr; |
| } |
| |
| static unsigned long to_guest_phys(const void *addr) |
| { |
| return (addr - guest_base); |
| } |
| |
| /*L:130 |
| * Loading the Kernel. |
| * |
| * We start with couple of simple helper routines. open_or_die() avoids |
| * error-checking code cluttering the callers: */ |
| 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; |
| } |
| |
| /* map_zeroed_pages() takes a number of pages. */ |
| static void *map_zeroed_pages(unsigned int num) |
| { |
| int fd = open_or_die("/dev/zero", O_RDONLY); |
| void *addr; |
| |
| /* We use a private mapping (ie. if we write to the page, it will be |
| * copied). */ |
| addr = mmap(NULL, getpagesize() * num, |
| PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, fd, 0); |
| if (addr == MAP_FAILED) |
| err(1, "Mmaping %u pages of /dev/zero", num); |
| |
| return addr; |
| } |
| |
| /* Get some more pages for a device. */ |
| static void *get_pages(unsigned int num) |
| { |
| void *addr = from_guest_phys(guest_limit); |
| |
| guest_limit += num * getpagesize(); |
| if (guest_limit > guest_max) |
| errx(1, "Not enough memory for devices"); |
| return addr; |
| } |
| |
| /* This routine is used to load the kernel or initrd. It tries mmap, but if |
| * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), |
| * it falls back to reading the memory in. */ |
| static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) |
| { |
| ssize_t r; |
| |
| /* We map writable even though for some segments are marked read-only. |
| * The kernel really wants to be writable: it patches its own |
| * instructions. |
| * |
| * MAP_PRIVATE means that the page won't be copied until a write is |
| * done to it. This allows us to share untouched memory between |
| * Guests. */ |
| if (mmap(addr, len, PROT_READ|PROT_WRITE|PROT_EXEC, |
| MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED) |
| return; |
| |
| /* pread does a seek and a read in one shot: saves a few lines. */ |
| r = pread(fd, addr, len, offset); |
| if (r != len) |
| err(1, "Reading offset %lu len %lu gave %zi", offset, len, r); |
| } |
| |
| /* This routine takes an open vmlinux image, which is in ELF, and maps it into |
| * the Guest memory. ELF = Embedded Linking Format, which is the format used |
| * by all modern binaries on Linux including the kernel. |
| * |
| * The ELF headers give *two* addresses: a physical address, and a virtual |
| * address. We use the physical address; the Guest will map itself to the |
| * virtual address. |
| * |
| * We return the starting address. */ |
| static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) |
| { |
| Elf32_Phdr phdr[ehdr->e_phnum]; |
| unsigned int i; |
| |
| /* Sanity checks on the main ELF header: an x86 executable with a |
| * reasonable number of correctly-sized program headers. */ |
| 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"); |
| |
| /* An ELF executable contains an ELF header and a number of "program" |
| * headers which indicate which parts ("segments") of the program to |
| * load where. */ |
| |
| /* We read in all the program headers at once: */ |
| 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"); |
| |
| /* Try all the headers: there are usually only three. A read-only one, |
| * a read-write one, and a "note" section which isn't loadable. */ |
| for (i = 0; i < ehdr->e_phnum; i++) { |
| /* If this isn't a loadable segment, we ignore it */ |
| 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 map this section of the file at its physical address. */ |
| map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), |
| phdr[i].p_offset, phdr[i].p_filesz); |
| } |
| |
| /* The entry point is given in the ELF header. */ |
| return ehdr->e_entry; |
| } |
| |
| /*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're |
| * supposed to jump into it and it will unpack itself. We used to have to |
| * perform some hairy magic because the unpacking code scared me. |
| * |
| * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote |
| * a small patch to jump over the tricky bits in the Guest, so now we just read |
| * the funky header so we know where in the file to load, and away we go! */ |
| static unsigned long load_bzimage(int fd) |
| { |
| struct boot_params boot; |
| int r; |
| /* Modern bzImages get loaded at 1M. */ |
| void *p = from_guest_phys(0x100000); |
| |
| /* Go back to the start of the file and read the header. It should be |
| * a Linux boot header (see Documentation/i386/boot.txt) */ |
| lseek(fd, 0, SEEK_SET); |
| read(fd, &boot, sizeof(boot)); |
| |
| /* Inside the setup_hdr, we expect the magic "HdrS" */ |
| if (memcmp(&boot.hdr.header, "HdrS", 4) != 0) |
| errx(1, "This doesn't look like a bzImage to me"); |
| |
| /* Skip over the extra sectors of the header. */ |
| lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET); |
| |
| /* Now read everything into memory. in nice big chunks. */ |
| while ((r = read(fd, p, 65536)) > 0) |
| p += r; |
| |
| /* Finally, code32_start tells us where to enter the kernel. */ |
| return boot.hdr.code32_start; |
| } |
| |
| /*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels |
| * come wrapped up in the self-decompressing "bzImage" format. With a little |
| * work, we can load those, too. */ |
| static unsigned long load_kernel(int fd) |
| { |
| Elf32_Ehdr hdr; |
| |
| /* Read in the first few bytes. */ |
| if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) |
| err(1, "Reading kernel"); |
| |
| /* If it's an ELF file, it starts with "\177ELF" */ |
| if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0) |
| return map_elf(fd, &hdr); |
| |
| /* Otherwise we assume it's a bzImage, and try to unpack it */ |
| return load_bzimage(fd); |
| } |
| |
| /* This is a trivial little helper to align pages. Andi Kleen hated it because |
| * it calls getpagesize() twice: "it's dumb code." |
| * |
| * Kernel guys get really het up about optimization, even when it's not |
| * necessary. I leave this code as a reaction against that. */ |
| static inline unsigned long page_align(unsigned long addr) |
| { |
| /* Add upwards and truncate downwards. */ |
| return ((addr + getpagesize()-1) & ~(getpagesize()-1)); |
| } |
| |
| /*L:180 An "initial ram disk" is a disk image loaded into memory along with |
| * the kernel which the kernel can use to boot from without needing any |
| * drivers. Most distributions now use this as standard: the initrd contains |
| * the code to load the appropriate driver modules for the current machine. |
| * |
| * Importantly, James Morris works for RedHat, and Fedora uses initrds for its |
| * kernels. He sent me this (and tells me when I break it). */ |
| static unsigned long load_initrd(const char *name, unsigned long mem) |
| { |
| int ifd; |
| struct stat st; |
| unsigned long len; |
| |
| ifd = open_or_die(name, O_RDONLY); |
| /* fstat() is needed to get the file size. */ |
| if (fstat(ifd, &st) < 0) |
| err(1, "fstat() on initrd '%s'", name); |
| |
| /* We map the initrd at the top of memory, but mmap wants it to be |
| * page-aligned, so we round the size up for that. */ |
| len = page_align(st.st_size); |
| map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); |
| /* Once a file is mapped, you can close the file descriptor. It's a |
| * little odd, but quite useful. */ |
| close(ifd); |
| verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len); |
| |
| /* We return the initrd size. */ |
| return len; |
| } |
| |
| /* Once we know how much memory we have, we can construct simple linear page |
| * tables which set virtual == physical which will get the Guest far enough |
| * into the boot to create its own. |
| * |
| * We lay them out of the way, just below the initrd (which is why we need to |
| * know its size). */ |
| static unsigned long setup_pagetables(unsigned long mem, |
| unsigned long initrd_size) |
| { |
| unsigned long *pgdir, *linear; |
| unsigned int mapped_pages, i, linear_pages; |
| unsigned int ptes_per_page = getpagesize()/sizeof(void *); |
| |
| mapped_pages = mem/getpagesize(); |
| |
| /* Each PTE page can map ptes_per_page pages: how many do we need? */ |
| linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page; |
| |
| /* We put the toplevel page directory page at the top of memory. */ |
| pgdir = from_guest_phys(mem) - initrd_size - getpagesize(); |
| |
| /* Now we use the next linear_pages pages as pte pages */ |
| linear = (void *)pgdir - linear_pages*getpagesize(); |
| |
| /* Linear mapping is easy: put every page's address into the mapping in |
| * order. PAGE_PRESENT contains the flags Present, Writable and |
| * Executable. */ |
| for (i = 0; i < mapped_pages; i++) |
| linear[i] = ((i * getpagesize()) | PAGE_PRESENT); |
| |
| /* The top level points to the linear page table pages above. */ |
| for (i = 0; i < mapped_pages; i += ptes_per_page) { |
| pgdir[i/ptes_per_page] |
| = ((to_guest_phys(linear) + i*sizeof(void *)) |
| | PAGE_PRESENT); |
| } |
| |
| verbose("Linear mapping of %u pages in %u pte pages at %#lx\n", |
| mapped_pages, linear_pages, to_guest_phys(linear)); |
| |
| /* We return the top level (guest-physical) address: the kernel needs |
| * to know where it is. */ |
| return to_guest_phys(pgdir); |
| } |
| /*:*/ |
| |
| /* Simple routine to roll all the commandline arguments together with spaces |
| * between them. */ |
| 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'; |
| } |
| |
| /*L:185 This is where we actually tell the kernel to initialize the Guest. We |
| * saw the arguments it expects when we looked at initialize() in lguest_user.c: |
| * the base of Guest "physical" memory, the top physical page to allow, the |
| * top level pagetable and the entry point for the Guest. */ |
| static int tell_kernel(unsigned long pgdir, unsigned long start) |
| { |
| unsigned long args[] = { LHREQ_INITIALIZE, |
| (unsigned long)guest_base, |
| guest_limit / getpagesize(), pgdir, start }; |
| int fd; |
| |
| verbose("Guest: %p - %p (%#lx)\n", |
| guest_base, guest_base + guest_limit, guest_limit); |
| fd = open_or_die("/dev/lguest", O_RDWR); |
| if (write(fd, args, sizeof(args)) < 0) |
| err(1, "Writing to /dev/lguest"); |
| |
| /* We return the /dev/lguest file descriptor to control this Guest */ |
| return fd; |
| } |
| /*:*/ |
| |
| static void add_device_fd(int fd) |
| { |
| FD_SET(fd, &devices.infds); |
| if (fd > devices.max_infd) |
| devices.max_infd = fd; |
| } |
| |
| /*L:200 |
| * The Waker. |
| * |
| * With console, block and network devices, we can have lots of input which we |
| * need to process. We could try to tell the kernel what file descriptors to |
| * watch, but handing a file descriptor mask through to the kernel is fairly |
| * icky. |
| * |
| * Instead, we fork off a process which watches the file descriptors and writes |
| * the LHREQ_BREAK command to the /dev/lguest file descriptor to tell the Host |
| * stop running the Guest. This causes the Launcher to return from the |
| * /dev/lguest read with -EAGAIN, where it will write to /dev/lguest to reset |
| * the LHREQ_BREAK and wake us up again. |
| * |
| * This, of course, is merely a different *kind* of icky. |
| */ |
| static void wake_parent(int pipefd, int lguest_fd) |
| { |
| /* Add the pipe from the Launcher to the fdset in the device_list, so |
| * we watch it, too. */ |
| add_device_fd(pipefd); |
| |
| for (;;) { |
| fd_set rfds = devices.infds; |
| unsigned long args[] = { LHREQ_BREAK, 1 }; |
| |
| /* Wait until input is ready from one of the devices. */ |
| select(devices.max_infd+1, &rfds, NULL, NULL, NULL); |
| /* Is it a message from the Launcher? */ |
| if (FD_ISSET(pipefd, &rfds)) { |
| int fd; |
| /* If read() returns 0, it means the Launcher has |
| * exited. We silently follow. */ |
| if (read(pipefd, &fd, sizeof(fd)) == 0) |
| exit(0); |
| /* Otherwise it's telling us to change what file |
| * descriptors we're to listen to. Positive means |
| * listen to a new one, negative means stop |
| * listening. */ |
| if (fd >= 0) |
| FD_SET(fd, &devices.infds); |
| else |
| FD_CLR(-fd - 1, &devices.infds); |
| } else /* Send LHREQ_BREAK command. */ |
| write(lguest_fd, args, sizeof(args)); |
| } |
| } |
| |
| /* This routine just sets up a pipe to the Waker process. */ |
| static int setup_waker(int lguest_fd) |
| { |
| int pipefd[2], child; |
| |
| /* We create a pipe to talk to the Waker, and also so it knows when the |
| * Launcher dies (and closes pipe). */ |
| pipe(pipefd); |
| child = fork(); |
| if (child == -1) |
| err(1, "forking"); |
| |
| if (child == 0) { |
| /* We are the Waker: close the "writing" end of our copy of the |
| * pipe and start waiting for input. */ |
| close(pipefd[1]); |
| wake_parent(pipefd[0], lguest_fd); |
| } |
| /* Close the reading end of our copy of the pipe. */ |
| close(pipefd[0]); |
| |
| /* Here is the fd used to talk to the waker. */ |
| return pipefd[1]; |
| } |
| |
| /* |
| * Device Handling. |
| * |
| * When the Guest gives us a buffer, it sends an array of addresses and sizes. |
| * We need to make sure it's not trying to reach into the Launcher itself, so |
| * we have a convenient routine which checks it and exits with an error message |
| * if something funny is going on: |
| */ |
| static void *_check_pointer(unsigned long addr, unsigned int size, |
| unsigned int line) |
| { |
| /* We have to separately check addr and addr+size, because size could |
| * be huge and addr + size might wrap around. */ |
| if (addr >= guest_limit || addr + size >= guest_limit) |
| errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr); |
| /* We return a pointer for the caller's convenience, now we know it's |
| * safe to use. */ |
| return from_guest_phys(addr); |
| } |
| /* A macro which transparently hands the line number to the real function. */ |
| #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) |
| |
| /* Each buffer in the virtqueues is actually a chain of descriptors. This |
| * function returns the next descriptor in the chain, or vq->vring.num if we're |
| * at the end. */ |
| static unsigned next_desc(struct virtqueue *vq, unsigned int i) |
| { |
| unsigned int next; |
| |
| /* If this descriptor says it doesn't chain, we're done. */ |
| if (!(vq->vring.desc[i].flags & VRING_DESC_F_NEXT)) |
| return vq->vring.num; |
| |
| /* Check they're not leading us off end of descriptors. */ |
| next = vq->vring.desc[i].next; |
| /* Make sure compiler knows to grab that: we don't want it changing! */ |
| wmb(); |
| |
| if (next >= vq->vring.num) |
| errx(1, "Desc next is %u", next); |
| |
| return next; |
| } |
| |
| /* This looks in the virtqueue and for the first available buffer, and converts |
| * it to an iovec for convenient access. Since descriptors consist of some |
| * number of output then some number of input descriptors, it's actually two |
| * iovecs, but we pack them into one and note how many of each there were. |
| * |
| * This function returns the descriptor number found, or vq->vring.num (which |
| * is never a valid descriptor number) if none was found. */ |
| static unsigned get_vq_desc(struct virtqueue *vq, |
| struct iovec iov[], |
| unsigned int *out_num, unsigned int *in_num) |
| { |
| unsigned int i, head; |
| |
| /* Check it isn't doing very strange things with descriptor numbers. */ |
| if ((u16)(vq->vring.avail->idx - vq->last_avail_idx) > vq->vring.num) |
| errx(1, "Guest moved used index from %u to %u", |
| vq->last_avail_idx, vq->vring.avail->idx); |
| |
| /* If there's nothing new since last we looked, return invalid. */ |
| if (vq->vring.avail->idx == vq->last_avail_idx) |
| return vq->vring.num; |
| |
| /* Grab the next descriptor number they're advertising, and increment |
| * the index we've seen. */ |
| head = vq->vring.avail->ring[vq->last_avail_idx++ % vq->vring.num]; |
| |
| /* If their number is silly, that's a fatal mistake. */ |
| if (head >= vq->vring.num) |
| errx(1, "Guest says index %u is available", head); |
| |
| /* When we start there are none of either input nor output. */ |
| *out_num = *in_num = 0; |
| |
| i = head; |
| do { |
| /* Grab the first descriptor, and check it's OK. */ |
| iov[*out_num + *in_num].iov_len = vq->vring.desc[i].len; |
| iov[*out_num + *in_num].iov_base |
| = check_pointer(vq->vring.desc[i].addr, |
| vq->vring.desc[i].len); |
| /* If this is an input descriptor, increment that count. */ |
| if (vq->vring.desc[i].flags & VRING_DESC_F_WRITE) |
| (*in_num)++; |
| else { |
| /* If it's an output descriptor, they're all supposed |
| * to come before any input descriptors. */ |
| if (*in_num) |
| errx(1, "Descriptor has out after in"); |
| (*out_num)++; |
| } |
| |
| /* If we've got too many, that implies a descriptor loop. */ |
| if (*out_num + *in_num > vq->vring.num) |
| errx(1, "Looped descriptor"); |
| } while ((i = next_desc(vq, i)) != vq->vring.num); |
| |
| return head; |
| } |
| |
| /* After we've used one of their buffers, we tell them about it. We'll then |
| * want to send them an interrupt, using trigger_irq(). */ |
| static void add_used(struct virtqueue *vq, unsigned int head, int len) |
| { |
| struct vring_used_elem *used; |
| |
| /* The virtqueue contains a ring of used buffers. Get a pointer to the |
| * next entry in that used ring. */ |
| used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num]; |
| used->id = head; |
| used->len = len; |
| /* Make sure buffer is written before we update index. */ |
| wmb(); |
| vq->vring.used->idx++; |
| } |
| |
| /* This actually sends the interrupt for this virtqueue */ |
| static void trigger_irq(int fd, struct virtqueue *vq) |
| { |
| unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; |
| |
| /* If they don't want an interrupt, don't send one. */ |
| if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) |
| return; |
| |
| /* Send the Guest an interrupt tell them we used something up. */ |
| if (write(fd, buf, sizeof(buf)) != 0) |
| err(1, "Triggering irq %i", vq->config.irq); |
| } |
| |
| /* And here's the combo meal deal. Supersize me! */ |
| static void add_used_and_trigger(int fd, struct virtqueue *vq, |
| unsigned int head, int len) |
| { |
| add_used(vq, head, len); |
| trigger_irq(fd, vq); |
| } |
| |
| /* |
| * The Console |
| * |
| * Here is the input terminal setting we save, and the routine to restore them |
| * on exit so the user gets their terminal back. */ |
| static struct termios orig_term; |
| static void restore_term(void) |
| { |
| tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); |
| } |
| |
| /* We associate some data with the console for our exit hack. */ |
| struct console_abort |
| { |
| /* How many times have they hit ^C? */ |
| int count; |
| /* When did they start? */ |
| struct timeval start; |
| }; |
| |
| /* This is the routine which handles console input (ie. stdin). */ |
| static bool handle_console_input(int fd, struct device *dev) |
| { |
| int len; |
| unsigned int head, in_num, out_num; |
| struct iovec iov[dev->vq->vring.num]; |
| struct console_abort *abort = dev->priv; |
| |
| /* First we need a console buffer from the Guests's input virtqueue. */ |
| head = get_vq_desc(dev->vq, iov, &out_num, &in_num); |
| |
| /* If they're not ready for input, stop listening to this file |
| * descriptor. We'll start again once they add an input buffer. */ |
| if (head == dev->vq->vring.num) |
| return false; |
| |
| if (out_num) |
| errx(1, "Output buffers in console in queue?"); |
| |
| /* This is why we convert to iovecs: the readv() call uses them, and so |
| * it reads straight into the Guest's buffer. */ |
| len = readv(dev->fd, iov, in_num); |
| if (len <= 0) { |
| /* This implies that the console is closed, is /dev/null, or |
| * something went terribly wrong. */ |
| warnx("Failed to get console input, ignoring console."); |
| /* Put the input terminal back. */ |
| restore_term(); |
| /* Remove callback from input vq, so it doesn't restart us. */ |
| dev->vq->handle_output = NULL; |
| /* Stop listening to this fd: don't call us again. */ |
| return false; |
| } |
| |
| /* Tell the Guest about the new input. */ |
| add_used_and_trigger(fd, dev->vq, head, len); |
| |
| /* Three ^C within one second? Exit. |
| * |
| * This is such a hack, but works surprisingly well. Each ^C has to be |
| * in a buffer by itself, so they can't be too fast. But we check that |
| * we get three within about a second, so they can't be too slow. */ |
| 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) { |
| unsigned long args[] = { LHREQ_BREAK, 0 }; |
| /* Close the fd so Waker will know it has to |
| * exit. */ |
| close(waker_fd); |
| /* Just in case waker is blocked in BREAK, send |
| * unbreak now. */ |
| write(fd, args, sizeof(args)); |
| exit(2); |
| } |
| abort->count = 0; |
| } |
| } else |
| /* Any other key resets the abort counter. */ |
| abort->count = 0; |
| |
| /* Everything went OK! */ |
| return true; |
| } |
| |
| /* Handling output for console is simple: we just get all the output buffers |
| * and write them to stdout. */ |
| static void handle_console_output(int fd, struct virtqueue *vq) |
| { |
| unsigned int head, out, in; |
| int len; |
| struct iovec iov[vq->vring.num]; |
| |
| /* Keep getting output buffers from the Guest until we run out. */ |
| while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { |
| if (in) |
| errx(1, "Input buffers in output queue?"); |
| len = writev(STDOUT_FILENO, iov, out); |
| add_used_and_trigger(fd, vq, head, len); |
| } |
| } |
| |
| /* |
| * The Network |
| * |
| * Handling output for network is also simple: we get all the output buffers |
| * and write them (ignoring the first element) to this device's file descriptor |
| * (stdout). */ |
| static void handle_net_output(int fd, struct virtqueue *vq) |
| { |
| unsigned int head, out, in; |
| int len; |
| struct iovec iov[vq->vring.num]; |
| |
| /* Keep getting output buffers from the Guest until we run out. */ |
| while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { |
| if (in) |
| errx(1, "Input buffers in output queue?"); |
| /* Check header, but otherwise ignore it (we told the Guest we |
| * supported no features, so it shouldn't have anything |
| * interesting). */ |
| (void)convert(&iov[0], struct virtio_net_hdr); |
| len = writev(vq->dev->fd, iov+1, out-1); |
| add_used_and_trigger(fd, vq, head, len); |
| } |
| } |
| |
| /* This is where we handle a packet coming in from the tun device to our |
| * Guest. */ |
| static bool handle_tun_input(int fd, struct device *dev) |
| { |
| unsigned int head, in_num, out_num; |
| int len; |
| struct iovec iov[dev->vq->vring.num]; |
| struct virtio_net_hdr *hdr; |
| |
| /* First we need a network buffer from the Guests's recv virtqueue. */ |
| head = get_vq_desc(dev->vq, iov, &out_num, &in_num); |
| if (head == dev->vq->vring.num) { |
| /* Now, it's expected that if we try to send a packet too |
| * early, the Guest won't be ready yet. Wait until the device |
| * status says it's ready. */ |
| /* FIXME: Actually want DRIVER_ACTIVE here. */ |
| if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) |
| warn("network: no dma buffer!"); |
| /* We'll turn this back on if input buffers are registered. */ |
| return false; |
| } else if (out_num) |
| errx(1, "Output buffers in network recv queue?"); |
| |
| /* First element is the header: we set it to 0 (no features). */ |
| hdr = convert(&iov[0], struct virtio_net_hdr); |
| hdr->flags = 0; |
| hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE; |
| |
| /* Read the packet from the device directly into the Guest's buffer. */ |
| len = readv(dev->fd, iov+1, in_num-1); |
| if (len <= 0) |
| err(1, "reading network"); |
| |
| /* Tell the Guest about the new packet. */ |
| add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len); |
| |
| verbose("tun input packet len %i [%02x %02x] (%s)\n", len, |
| ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1], |
| head != dev->vq->vring.num ? "sent" : "discarded"); |
| |
| /* All good. */ |
| return true; |
| } |
| |
| /*L:215 This is the callback attached to the network and console input |
| * virtqueues: it ensures we try again, in case we stopped console or net |
| * delivery because Guest didn't have any buffers. */ |
| static void enable_fd(int fd, struct virtqueue *vq) |
| { |
| add_device_fd(vq->dev->fd); |
| /* Tell waker to listen to it again */ |
| write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd)); |
| } |
| |
| /* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */ |
| static void handle_output(int fd, unsigned long addr) |
| { |
| struct device *i; |
| struct virtqueue *vq; |
| |
| /* Check each virtqueue. */ |
| for (i = devices.dev; i; i = i->next) { |
| for (vq = i->vq; vq; vq = vq->next) { |
| if (vq->config.pfn == addr/getpagesize() |
| && vq->handle_output) { |
| verbose("Output to %s\n", vq->dev->name); |
| vq->handle_output(fd, vq); |
| return; |
| } |
| } |
| } |
| |
| /* Early console write is done using notify on a nul-terminated string |
| * in Guest memory. */ |
| if (addr >= guest_limit) |
| errx(1, "Bad NOTIFY %#lx", addr); |
| |
| write(STDOUT_FILENO, from_guest_phys(addr), |
| strnlen(from_guest_phys(addr), guest_limit - addr)); |
| } |
| |
| /* This is called when the Waker wakes us up: check for incoming file |
| * descriptors. */ |
| static void handle_input(int fd) |
| { |
| /* select() wants a zeroed timeval to mean "don't wait". */ |
| struct timeval poll = { .tv_sec = 0, .tv_usec = 0 }; |
| |
| for (;;) { |
| struct device *i; |
| fd_set fds = devices.infds; |
| |
| /* If nothing is ready, we're done. */ |
| if (select(devices.max_infd+1, &fds, NULL, NULL, &poll) == 0) |
| break; |
| |
| /* Otherwise, call the device(s) which have readable |
| * file descriptors and a method of handling them. */ |
| for (i = devices.dev; i; i = i->next) { |
| if (i->handle_input && FD_ISSET(i->fd, &fds)) { |
| int dev_fd; |
| if (i->handle_input(fd, i)) |
| continue; |
| |
| /* If handle_input() returns false, it means we |
| * should no longer service it. Networking and |
| * console do this when there's no input |
| * buffers to deliver into. Console also uses |
| * it when it discovers that stdin is |
| * closed. */ |
| FD_CLR(i->fd, &devices.infds); |
| /* Tell waker to ignore it too, by sending a |
| * negative fd number (-1, since 0 is a valid |
| * FD number). */ |
| dev_fd = -i->fd - 1; |
| write(waker_fd, &dev_fd, sizeof(dev_fd)); |
| } |
| } |
| } |
| } |
| |
| /*L:190 |
| * Device Setup |
| * |
| * All devices need a descriptor so the Guest knows it exists, and a "struct |
| * device" so the Launcher can keep track of it. We have common helper |
| * routines to allocate them. |
| * |
| * This routine allocates a new "struct lguest_device_desc" from descriptor |
| * table just above the Guest's normal memory. It returns a pointer to that |
| * descriptor. */ |
| static struct lguest_device_desc *new_dev_desc(u16 type) |
| { |
| struct lguest_device_desc *d; |
| |
| /* We only have one page for all the descriptors. */ |
| if (devices.desc_used + sizeof(*d) > getpagesize()) |
| errx(1, "Too many devices"); |
| |
| /* We don't need to set config_len or status: page is 0 already. */ |
| d = (void *)devices.descpage + devices.desc_used; |
| d->type = type; |
| devices.desc_used += sizeof(*d); |
| |
| return d; |
| } |
| |
| /* Each device descriptor is followed by some configuration information. |
| * Each configuration field looks like: u8 type, u8 len, [... len bytes...]. |
| * |
| * This routine adds a new field to an existing device's descriptor. It only |
| * works for the last device, but that's OK because that's how we use it. */ |
| static void add_desc_field(struct device *dev, u8 type, u8 len, const void *c) |
| { |
| /* This is the last descriptor, right? */ |
| assert(devices.descpage + devices.desc_used |
| == (u8 *)(dev->desc + 1) + dev->desc->config_len); |
| |
| /* We only have one page of device descriptions. */ |
| if (devices.desc_used + 2 + len > getpagesize()) |
| errx(1, "Too many devices"); |
| |
| /* Copy in the new config header: type then length. */ |
| devices.descpage[devices.desc_used++] = type; |
| devices.descpage[devices.desc_used++] = len; |
| memcpy(devices.descpage + devices.desc_used, c, len); |
| devices.desc_used += len; |
| |
| /* Update the device descriptor length: two byte head then data. */ |
| dev->desc->config_len += 2 + len; |
| } |
| |
| /* This routine adds a virtqueue to a device. We specify how many descriptors |
| * the virtqueue is to have. */ |
| static void add_virtqueue(struct device *dev, unsigned int num_descs, |
| void (*handle_output)(int fd, struct virtqueue *me)) |
| { |
| unsigned int pages; |
| struct virtqueue **i, *vq = malloc(sizeof(*vq)); |
| void *p; |
| |
| /* First we need some pages for this virtqueue. */ |
| pages = (vring_size(num_descs) + getpagesize() - 1) / getpagesize(); |
| p = get_pages(pages); |
| |
| /* Initialize the configuration. */ |
| vq->config.num = num_descs; |
| vq->config.irq = devices.next_irq++; |
| vq->config.pfn = to_guest_phys(p) / getpagesize(); |
| |
| /* Initialize the vring. */ |
| vring_init(&vq->vring, num_descs, p); |
| |
| /* Add the configuration information to this device's descriptor. */ |
| add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE, |
| sizeof(vq->config), &vq->config); |
| |
| /* Add to tail of list, so dev->vq is first vq, dev->vq->next is |
| * second. */ |
| for (i = &dev->vq; *i; i = &(*i)->next); |
| *i = vq; |
| |
| /* Link virtqueue back to device. */ |
| vq->dev = dev; |
| |
| /* Set the routine to call when the Guest does something to this |
| * virtqueue. */ |
| vq->handle_output = handle_output; |
| |
| /* Set the "Don't Notify Me" flag if we don't have a handler */ |
| if (!handle_output) |
| vq->vring.used->flags = VRING_USED_F_NO_NOTIFY; |
| } |
| |
| /* This routine does all the creation and setup of a new device, including |
| * calling new_dev_desc() to allocate the descriptor and device memory. */ |
| static struct device *new_device(const char *name, u16 type, int fd, |
| bool (*handle_input)(int, struct device *)) |
| { |
| struct device *dev = malloc(sizeof(*dev)); |
| |
| /* Append to device list. Prepending to a single-linked list is |
| * easier, but the user expects the devices to be arranged on the bus |
| * in command-line order. The first network device on the command line |
| * is eth0, the first block device /dev/vda, etc. */ |
| *devices.lastdev = dev; |
| dev->next = NULL; |
| devices.lastdev = &dev->next; |
| |
| /* Now we populate the fields one at a time. */ |
| dev->fd = fd; |
| /* If we have an input handler for this file descriptor, then we add it |
| * to the device_list's fdset and maxfd. */ |
| if (handle_input) |
| add_device_fd(dev->fd); |
| dev->desc = new_dev_desc(type); |
| dev->handle_input = handle_input; |
| dev->name = name; |
| return dev; |
| } |
| |
| /* Our first setup routine is the console. It's a fairly simple device, but |
| * UNIX tty handling makes it uglier than it could be. */ |
| static void setup_console(void) |
| { |
| struct device *dev; |
| |
| /* If we can save the initial standard input settings... */ |
| if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { |
| struct termios term = orig_term; |
| /* Then we turn off echo, line buffering and ^C etc. We want a |
| * raw input stream to the Guest. */ |
| term.c_lflag &= ~(ISIG|ICANON|ECHO); |
| tcsetattr(STDIN_FILENO, TCSANOW, &term); |
| /* If we exit gracefully, the original settings will be |
| * restored so the user can see what they're typing. */ |
| atexit(restore_term); |
| } |
| |
| dev = new_device("console", VIRTIO_ID_CONSOLE, |
| STDIN_FILENO, handle_console_input); |
| /* We store the console state in dev->priv, and initialize it. */ |
| dev->priv = malloc(sizeof(struct console_abort)); |
| ((struct console_abort *)dev->priv)->count = 0; |
| |
| /* The console needs two virtqueues: the input then the output. When |
| * they put something the input queue, we make sure we're listening to |
| * stdin. When they put something in the output queue, we write it to |
| * stdout. */ |
| add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); |
| add_virtqueue(dev, VIRTQUEUE_NUM, handle_console_output); |
| |
| verbose("device %u: console\n", devices.device_num++); |
| } |
| /*:*/ |
| |
| /*M:010 Inter-guest networking is an interesting area. Simplest is to have a |
| * --sharenet=<name> option which opens or creates a named pipe. This can be |
| * used to send packets to another guest in a 1:1 manner. |
| * |
| * More sopisticated is to use one of the tools developed for project like UML |
| * to do networking. |
| * |
| * Faster is to do virtio bonding in kernel. Doing this 1:1 would be |
| * completely generic ("here's my vring, attach to your vring") and would work |
| * for any traffic. Of course, namespace and permissions issues need to be |
| * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide |
| * multiple inter-guest channels behind one interface, although it would |
| * require some manner of hotplugging new virtio channels. |
| * |
| * Finally, we could implement a virtio network switch in the kernel. :*/ |
| |
| 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]; |
| } |
| |
| /* This code is "adapted" from libbridge: it attaches the Host end of the |
| * network device to the bridge device specified by the command line. |
| * |
| * This is yet another James Morris contribution (I'm an IP-level guy, so I |
| * dislike bridging), and I just try not to break it. */ |
| 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); |
| } |
| |
| /* This sets up the Host end of the network device with an IP address, brings |
| * it up so packets will flow, the copies the MAC address into the hwaddr |
| * pointer. */ |
| 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; |
| |
| /* Don't read these incantations. Just cut & paste them like I did! */ |
| 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); |
| |
| /* SIOC stands for Socket I/O Control. G means Get (vs S for Set |
| * above). IF means Interface, and HWADDR is hardware address. |
| * Simple! */ |
| if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0) |
| err(1, "getting hw address for %s", devname); |
| memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6); |
| } |
| |
| /*L:195 Our network is a Host<->Guest network. This can either use bridging or |
| * routing, but the principle is the same: it uses the "tun" device to inject |
| * packets into the Host as if they came in from a normal network card. We |
| * just shunt packets between the Guest and the tun device. */ |
| static void setup_tun_net(const char *arg) |
| { |
| struct device *dev; |
| struct ifreq ifr; |
| int netfd, ipfd; |
| u32 ip; |
| const char *br_name = NULL; |
| u8 hwaddr[6]; |
| |
| /* We open the /dev/net/tun device and tell it we want a tap device. A |
| * tap device is like a tun device, only somehow different. To tell |
| * the truth, I completely blundered my way through this code, but it |
| * works now! */ |
| 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"); |
| /* We don't need checksums calculated for packets coming in this |
| * device: trust us! */ |
| ioctl(netfd, TUNSETNOCSUM, 1); |
| |
| /* First we create a new network device. */ |
| dev = new_device("net", VIRTIO_ID_NET, netfd, handle_tun_input); |
| |
| /* Network devices need a receive and a send queue, just like |
| * console. */ |
| add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); |
| add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output); |
| |
| /* We need a socket to perform the magic network ioctls to bring up the |
| * tap interface, connect to the bridge etc. Any socket will do! */ |
| ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); |
| if (ipfd < 0) |
| err(1, "opening IP socket"); |
| |
| /* If the command line was --tunnet=bridge:<name> do bridging. */ |
| 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 /* It is an IP address to set up the device with */ |
| ip = str2ip(arg); |
| |
| /* Set up the tun device, and get the mac address for the interface. */ |
| configure_device(ipfd, ifr.ifr_name, ip, hwaddr); |
| |
| /* Tell Guest what MAC address to use. */ |
| add_desc_field(dev, VIRTIO_CONFIG_NET_MAC_F, sizeof(hwaddr), hwaddr); |
| |
| /* We don't seed the socket any more; setup is done. */ |
| close(ipfd); |
| |
| verbose("device %u: tun net %u.%u.%u.%u\n", |
| devices.device_num++, |
| (u8)(ip>>24),(u8)(ip>>16),(u8)(ip>>8),(u8)ip); |
| if (br_name) |
| verbose("attached to bridge: %s\n", br_name); |
| } |
| |
| /* Our block (disk) device should be really simple: the Guest asks for a block |
| * number and we read or write that position in the file. Unfortunately, that |
| * was amazingly slow: the Guest waits until the read is finished before |
| * running anything else, even if it could have been doing useful work. |
| * |
| * We could use async I/O, except it's reputed to suck so hard that characters |
| * actually go missing from your code when you try to use it. |
| * |
| * So we farm the I/O out to thread, and communicate with it via a pipe. */ |
| |
| /* This hangs off device->priv. */ |
| struct vblk_info |
| { |
| /* The size of the file. */ |
| off64_t len; |
| |
| /* The file descriptor for the file. */ |
| int fd; |
| |
| /* IO thread listens on this file descriptor [0]. */ |
| int workpipe[2]; |
| |
| /* IO thread writes to this file descriptor to mark it done, then |
| * Launcher triggers interrupt to Guest. */ |
| int done_fd; |
| }; |
| /*:*/ |
| |
| /*L:210 |
| * The Disk |
| * |
| * Remember that the block device is handled by a separate I/O thread. We head |
| * straight into the core of that thread here: |
| */ |
| static bool service_io(struct device *dev) |
| { |
| struct vblk_info *vblk = dev->priv; |
| unsigned int head, out_num, in_num, wlen; |
| int ret; |
| struct virtio_blk_inhdr *in; |
| struct virtio_blk_outhdr *out; |
| struct iovec iov[dev->vq->vring.num]; |
| off64_t off; |
| |
| /* See if there's a request waiting. If not, nothing to do. */ |
| head = get_vq_desc(dev->vq, iov, &out_num, &in_num); |
| if (head == dev->vq->vring.num) |
| return false; |
| |
| /* Every block request should contain at least one output buffer |
| * (detailing the location on disk and the type of request) and one |
| * input buffer (to hold the result). */ |
| if (out_num == 0 || in_num == 0) |
| errx(1, "Bad virtblk cmd %u out=%u in=%u", |
| head, out_num, in_num); |
| |
| out = convert(&iov[0], struct virtio_blk_outhdr); |
| in = convert(&iov[out_num+in_num-1], struct virtio_blk_inhdr); |
| off = out->sector * 512; |
| |
| /* The block device implements "barriers", where the Guest indicates |
| * that it wants all previous writes to occur before this write. We |
| * don't have a way of asking our kernel to do a barrier, so we just |
| * synchronize all the data in the file. Pretty poor, no? */ |
| if (out->type & VIRTIO_BLK_T_BARRIER) |
| fdatasync(vblk->fd); |
| |
| /* In general the virtio block driver is allowed to try SCSI commands. |
| * It'd be nice if we supported eject, for example, but we don't. */ |
| if (out->type & VIRTIO_BLK_T_SCSI_CMD) { |
| fprintf(stderr, "Scsi commands unsupported\n"); |
| in->status = VIRTIO_BLK_S_UNSUPP; |
| wlen = sizeof(*in); |
| } else if (out->type & VIRTIO_BLK_T_OUT) { |
| /* Write */ |
| |
| /* Move to the right location in the block file. This can fail |
| * if they try to write past end. */ |
| if (lseek64(vblk->fd, off, SEEK_SET) != off) |
| err(1, "Bad seek to sector %llu", out->sector); |
| |
| ret = writev(vblk->fd, iov+1, out_num-1); |
| verbose("WRITE to sector %llu: %i\n", out->sector, ret); |
| |
| /* Grr... Now we know how long the descriptor they sent was, we |
| * make sure they didn't try to write over the end of the block |
| * file (possibly extending it). */ |
| if (ret > 0 && off + ret > vblk->len) { |
| /* Trim it back to the correct length */ |
| ftruncate64(vblk->fd, vblk->len); |
| /* Die, bad Guest, die. */ |
| errx(1, "Write past end %llu+%u", off, ret); |
| } |
| wlen = sizeof(*in); |
| in->status = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); |
| } else { |
| /* Read */ |
| |
| /* Move to the right location in the block file. This can fail |
| * if they try to read past end. */ |
| if (lseek64(vblk->fd, off, SEEK_SET) != off) |
| err(1, "Bad seek to sector %llu", out->sector); |
| |
| ret = readv(vblk->fd, iov+1, in_num-1); |
| verbose("READ from sector %llu: %i\n", out->sector, ret); |
| if (ret >= 0) { |
| wlen = sizeof(*in) + ret; |
| in->status = VIRTIO_BLK_S_OK; |
| } else { |
| wlen = sizeof(*in); |
| in->status = VIRTIO_BLK_S_IOERR; |
| } |
| } |
| |
| /* We can't trigger an IRQ, because we're not the Launcher. It does |
| * that when we tell it we're done. */ |
| add_used(dev->vq, head, wlen); |
| return true; |
| } |
| |
| /* This is the thread which actually services the I/O. */ |
| static int io_thread(void *_dev) |
| { |
| struct device *dev = _dev; |
| struct vblk_info *vblk = dev->priv; |
| char c; |
| |
| /* Close other side of workpipe so we get 0 read when main dies. */ |
| close(vblk->workpipe[1]); |
| /* Close the other side of the done_fd pipe. */ |
| close(dev->fd); |
| |
| /* When this read fails, it means Launcher died, so we follow. */ |
| while (read(vblk->workpipe[0], &c, 1) == 1) { |
| /* We acknowledge each request immediately to reduce latency, |
| * rather than waiting until we've done them all. I haven't |
| * measured to see if it makes any difference. */ |
| while (service_io(dev)) |
| write(vblk->done_fd, &c, 1); |
| } |
| return 0; |
| } |
| |
| /* Now we've seen the I/O thread, we return to the Launcher to see what happens |
| * when the thread tells us it's completed some I/O. */ |
| static bool handle_io_finish(int fd, struct device *dev) |
| { |
| char c; |
| |
| /* If the I/O thread died, presumably it printed the error, so we |
| * simply exit. */ |
| if (read(dev->fd, &c, 1) != 1) |
| exit(1); |
| |
| /* It did some work, so trigger the irq. */ |
| trigger_irq(fd, dev->vq); |
| return true; |
| } |
| |
| /* When the Guest submits some I/O, we just need to wake the I/O thread. */ |
| static void handle_virtblk_output(int fd, struct virtqueue *vq) |
| { |
| struct vblk_info *vblk = vq->dev->priv; |
| char c = 0; |
| |
| /* Wake up I/O thread and tell it to go to work! */ |
| if (write(vblk->workpipe[1], &c, 1) != 1) |
| /* Presumably it indicated why it died. */ |
| exit(1); |
| } |
| |
| /*L:198 This actually sets up a virtual block device. */ |
| static void setup_block_file(const char *filename) |
| { |
| int p[2]; |
| struct device *dev; |
| struct vblk_info *vblk; |
| void *stack; |
| u64 cap; |
| unsigned int val; |
| |
| /* This is the pipe the I/O thread will use to tell us I/O is done. */ |
| pipe(p); |
| |
| /* The device responds to return from I/O thread. */ |
| dev = new_device("block", VIRTIO_ID_BLOCK, p[0], handle_io_finish); |
| |
| /* The device has one virtqueue, where the Guest places requests. */ |
| add_virtqueue(dev, VIRTQUEUE_NUM, handle_virtblk_output); |
| |
| /* Allocate the room for our own bookkeeping */ |
| vblk = dev->priv = malloc(sizeof(*vblk)); |
| |
| /* First we open the file and store the length. */ |
| vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); |
| vblk->len = lseek64(vblk->fd, 0, SEEK_END); |
| |
| /* Tell Guest how many sectors this device has. */ |
| cap = cpu_to_le64(vblk->len / 512); |
| add_desc_field(dev, VIRTIO_CONFIG_BLK_F_CAPACITY, sizeof(cap), &cap); |
| |
| /* Tell Guest not to put in too many descriptors at once: two are used |
| * for the in and out elements. */ |
| val = cpu_to_le32(VIRTQUEUE_NUM - 2); |
| add_desc_field(dev, VIRTIO_CONFIG_BLK_F_SEG_MAX, sizeof(val), &val); |
| |
| /* The I/O thread writes to this end of the pipe when done. */ |
| vblk->done_fd = p[1]; |
| |
| /* This is the second pipe, which is how we tell the I/O thread about |
| * more work. */ |
| pipe(vblk->workpipe); |
| |
| /* Create stack for thread and run it */ |
| stack = malloc(32768); |
| if (clone(io_thread, stack + 32768, CLONE_VM, dev) == -1) |
| err(1, "Creating clone"); |
| |
| /* We don't need to keep the I/O thread's end of the pipes open. */ |
| close(vblk->done_fd); |
| close(vblk->workpipe[0]); |
| |
| verbose("device %u: virtblock %llu sectors\n", |
| devices.device_num, cap); |
| } |
| /* That's the end of device setup. */ |
| |
| /*L:220 Finally we reach the core of the Launcher, which runs the Guest, serves |
| * its input and output, and finally, lays it to rest. */ |
| static void __attribute__((noreturn)) run_guest(int lguest_fd) |
| { |
| for (;;) { |
| unsigned long args[] = { LHREQ_BREAK, 0 }; |
| unsigned long notify_addr; |
| int readval; |
| |
| /* We read from the /dev/lguest device to run the Guest. */ |
| readval = read(lguest_fd, ¬ify_addr, sizeof(notify_addr)); |
| |
| /* One unsigned long means the Guest did HCALL_NOTIFY */ |
| if (readval == sizeof(notify_addr)) { |
| verbose("Notify on address %#lx\n", notify_addr); |
| handle_output(lguest_fd, notify_addr); |
| continue; |
| /* ENOENT means the Guest died. Reading tells us why. */ |
| } else if (errno == ENOENT) { |
| char reason[1024] = { 0 }; |
| read(lguest_fd, reason, sizeof(reason)-1); |
| errx(1, "%s", reason); |
| /* EAGAIN means the Waker wanted us to look at some input. |
| * Anything else means a bug or incompatible change. */ |
| } else if (errno != EAGAIN) |
| err(1, "Running guest failed"); |
| |
| /* Service input, then unset the BREAK to release the Waker. */ |
| handle_input(lguest_fd); |
| if (write(lguest_fd, args, sizeof(args)) < 0) |
| err(1, "Resetting break"); |
| } |
| } |
| /* |
| * This is the end of the Launcher. The good news: we are over halfway |
| * through! The bad news: the most fiendish part of the code still lies ahead |
| * of us. |
| * |
| * Are you ready? Take a deep breath and join me in the core of the Host, in |
| * "make Host". |
| :*/ |
| |
| static struct option opts[] = { |
| { "verbose", 0, NULL, 'v' }, |
| { "tunnet", 1, NULL, 't' }, |
| { "block", 1, NULL, 'b' }, |
| { "initrd", 1, NULL, 'i' }, |
| { NULL }, |
| }; |
| static void usage(void) |
| { |
| errx(1, "Usage: lguest [--verbose] " |
| "[--tunnet=(<ipaddr>|bridge:<bridgename>)\n" |
| "|--block=<filename>|--initrd=<filename>]...\n" |
| "<mem-in-mb> vmlinux [args...]"); |
| } |
| |
| /*L:105 The main routine is where the real work begins: */ |
| int main(int argc, char *argv[]) |
| { |
| /* Memory, top-level pagetable, code startpoint and size of the |
| * (optional) initrd. */ |
| unsigned long mem = 0, pgdir, start, initrd_size = 0; |
| /* Two temporaries and the /dev/lguest file descriptor. */ |
| int i, c, lguest_fd; |
| /* The boot information for the Guest. */ |
| struct boot_params *boot; |
| /* If they specify an initrd file to load. */ |
| const char *initrd_name = NULL; |
| |
| /* First we initialize the device list. Since console and network |
| * device receive input from a file descriptor, we keep an fdset |
| * (infds) and the maximum fd number (max_infd) with the head of the |
| * list. We also keep a pointer to the last device, for easy appending |
| * to the list. Finally, we keep the next interrupt number to hand out |
| * (1: remember that 0 is used by the timer). */ |
| FD_ZERO(&devices.infds); |
| devices.max_infd = -1; |
| devices.lastdev = &devices.dev; |
| devices.next_irq = 1; |
| |
| /* We need to know how much memory so we can set up the device |
| * descriptor and memory pages for the devices as we parse the command |
| * line. So we quickly look through the arguments to find the amount |
| * of memory now. */ |
| for (i = 1; i < argc; i++) { |
| if (argv[i][0] != '-') { |
| mem = atoi(argv[i]) * 1024 * 1024; |
| /* We start by mapping anonymous pages over all of |
| * guest-physical memory range. This fills it with 0, |
| * and ensures that the Guest won't be killed when it |
| * tries to access it. */ |
| guest_base = map_zeroed_pages(mem / getpagesize() |
| + DEVICE_PAGES); |
| guest_limit = mem; |
| guest_max = mem + DEVICE_PAGES*getpagesize(); |
| devices.descpage = get_pages(1); |
| break; |
| } |
| } |
| |
| /* The options are fairly straight-forward */ |
| while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) { |
| switch (c) { |
| case 'v': |
| verbose = true; |
| break; |
| case 't': |
| setup_tun_net(optarg); |
| break; |
| case 'b': |
| setup_block_file(optarg); |
| break; |
| case 'i': |
| initrd_name = optarg; |
| break; |
| default: |
| warnx("Unknown argument %s", argv[optind]); |
| usage(); |
| } |
| } |
| /* After the other arguments we expect memory and kernel image name, |
| * followed by command line arguments for the kernel. */ |
| if (optind + 2 > argc) |
| usage(); |
| |
| verbose("Guest base is at %p\n", guest_base); |
| |
| /* We always have a console device */ |
| setup_console(); |
| |
| /* Now we load the kernel */ |
| start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); |
| |
| /* Boot information is stashed at physical address 0 */ |
| boot = from_guest_phys(0); |
| |
| /* Map the initrd image if requested (at top of physical memory) */ |
| if (initrd_name) { |
| initrd_size = load_initrd(initrd_name, mem); |
| /* These are the location in the Linux boot header where the |
| * start and size of the initrd are expected to be found. */ |
| boot->hdr.ramdisk_image = mem - initrd_size; |
| boot->hdr.ramdisk_size = initrd_size; |
| /* The bootloader type 0xFF means "unknown"; that's OK. */ |
| boot->hdr.type_of_loader = 0xFF; |
| } |
| |
| /* Set up the initial linear pagetables, starting below the initrd. */ |
| pgdir = setup_pagetables(mem, initrd_size); |
| |
| /* The Linux boot header contains an "E820" memory map: ours is a |
| * simple, single region. */ |
| boot->e820_entries = 1; |
| boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM }); |
| /* The boot header contains a command line pointer: we put the command |
| * line after the boot header. */ |
| boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1); |
| /* We use a simple helper to copy the arguments separated by spaces. */ |
| concat((char *)(boot + 1), argv+optind+2); |
| |
| /* Boot protocol version: 2.07 supports the fields for lguest. */ |
| boot->hdr.version = 0x207; |
| |
| /* The hardware_subarch value of "1" tells the Guest it's an lguest. */ |
| boot->hdr.hardware_subarch = 1; |
| |
| /* Tell the entry path not to try to reload segment registers. */ |
| boot->hdr.loadflags |= KEEP_SEGMENTS; |
| |
| /* We tell the kernel to initialize the Guest: this returns the open |
| * /dev/lguest file descriptor. */ |
| lguest_fd = tell_kernel(pgdir, start); |
| |
| /* We fork off a child process, which wakes the Launcher whenever one |
| * of the input file descriptors needs attention. Otherwise we would |
| * run the Guest until it tries to output something. */ |
| waker_fd = setup_waker(lguest_fd); |
| |
| /* Finally, run the Guest. This doesn't return. */ |
| run_guest(lguest_fd); |
| } |
| /*:*/ |
| |
| /*M:999 |
| * Mastery is done: you now know everything I do. |
| * |
| * But surely you have seen code, features and bugs in your wanderings which |
| * you now yearn to attack? That is the real game, and I look forward to you |
| * patching and forking lguest into the Your-Name-Here-visor. |
| * |
| * Farewell, and good coding! |
| * Rusty Russell. |
| */ |