This patch introduces helper function for postcopy to access umem char device and to communicate between incoming-qemu and umemd.
Signed-off-by: Isaku Yamahata <yamah...@valinux.co.jp> --- changes v2 -> v3: - error check, don't abort - typedef - #ifdef CONFIG_LINUX - code simplification changes v1 -> v2: - code simplification - make fault trigger more robust - introduce struct umem_pages --- umem.c | 291 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ umem.h | 88 ++++++++++++++++++++ 2 files changed, 379 insertions(+) create mode 100644 umem.c create mode 100644 umem.h diff --git a/umem.c b/umem.c new file mode 100644 index 0000000..b05377b --- /dev/null +++ b/umem.c @@ -0,0 +1,291 @@ +/* + * umem.c: user process backed memory module for postcopy livemigration + * + * Copyright (c) 2011 + * National Institute of Advanced Industrial Science and Technology + * + * https://sites.google.com/site/grivonhome/quick-kvm-migration + * Author: Isaku Yamahata <yamahata at valinux co jp> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <sys/ioctl.h> +#include <sys/mman.h> + +#include "config-host.h" +#ifdef CONFIG_LINUX +#include <linux/uvmem.h> +#endif + +#include "bitops.h" +#include "sysemu.h" +#include "hw/hw.h" +#include "umem.h" + +//#define DEBUG_UMEM +#ifdef DEBUG_UMEM +#define DPRINTF(format, ...) \ + do { \ + printf("%s:%d "format, __func__, __LINE__, ## __VA_ARGS__); \ + } while (0) +#else +#define DPRINTF(format, ...) do { } while (0) +#endif + +#define DEV_UMEM "/dev/uvmem" + +int umem_new(void *hostp, size_t size, UMem** umemp) +{ +#ifdef CONFIG_LINUX + struct uvmem_init uinit = { + .size = size, + .shmem_fd = -1, + }; + UMem *umem; + int error; + + assert((size % getpagesize()) == 0); + umem = g_new(UMem, 1); + umem->fd = open(DEV_UMEM, O_RDWR); + if (umem->fd < 0) { + error = -errno; + perror("can't open "DEV_UMEM); + goto error; + } + + if (ioctl(umem->fd, UVMEM_INIT, &uinit) < 0) { + error = -errno; + perror("UMEM_INIT failed"); + goto error; + } + if (ftruncate(uinit.shmem_fd, uinit.size) < 0) { + error = -errno; + perror("truncate(\"shmem_fd\") failed"); + goto error; + } + + umem->nbits = 0; + umem->nsets = 0; + umem->faulted = NULL; + umem->page_shift = ffs(getpagesize()) - 1; + umem->shmem_fd = uinit.shmem_fd; + umem->size = uinit.size; + umem->umem = mmap(hostp, size, PROT_EXEC | PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_FIXED, umem->fd, 0); + if (umem->umem == MAP_FAILED) { + error = -errno; + perror("mmap(UMem) failed"); + goto error; + } + *umemp = umem; + return 0; + +error: + if (umem->fd >= 0) { + close(umem->fd); + } + if (uinit.shmem_fd >= 0) { + close(uinit.shmem_fd); + } + g_free(umem); + return error; +#else + perror("postcopy migration is not supported"); + return -ENOSYS; +#endif +} + +void umem_destroy(UMem *umem) +{ + if (umem->fd != -1) { + close(umem->fd); + } + if (umem->shmem_fd != -1) { + close(umem->shmem_fd); + } + g_free(umem->faulted); + g_free(umem); +} + +size_t umem_pages_size(uint64_t nr) +{ + return sizeof(UMemPages) + nr * sizeof(uint64_t); +} + +int umem_get_page_request(UMem *umem, UMemPages *page_request) +{ + ssize_t ret = read(umem->fd, page_request->pgoffs, + page_request->nr * sizeof(page_request->pgoffs[0])); + if (ret < 0) { + if (errno != EINTR) { + perror("daemon: umem read failed"); + return -errno; + } + ret = 0; + } + page_request->nr = ret / sizeof(page_request->pgoffs[0]); + return 0; +} + +int umem_mark_page_cached(UMem *umem, UMemPages *page_cached) +{ + const void *buf = page_cached->pgoffs; + size_t size = page_cached->nr * sizeof(page_cached->pgoffs[0]); + ssize_t ret; + + ret = qemu_write_full(umem->fd, buf, size); + if (ret != size) { + perror("daemon: umem write"); + return -errno; + } + return 0; +} + +void umem_unmap(UMem *umem) +{ + munmap(umem->umem, umem->size); + umem->umem = NULL; +} + +void umem_close(UMem *umem) +{ + close(umem->fd); + umem->fd = -1; +} + +int umem_map_shmem(UMem *umem) +{ + umem->nbits = umem->size >> umem->page_shift; + umem->nsets = 0; + umem->faulted = g_new0(unsigned long, BITS_TO_LONGS(umem->nbits)); + + umem->shmem = mmap(NULL, umem->size, PROT_READ | PROT_WRITE, MAP_SHARED, + umem->shmem_fd, 0); + if (umem->shmem == MAP_FAILED) { + perror("daemon: mmap(\"shmem\")"); + return -errno; + } + return 0; +} + +void umem_unmap_shmem(UMem *umem) +{ + if (umem->shmem) { + munmap(umem->shmem, umem->size); + umem->shmem = NULL; + } +} + +void umem_remove_shmem(UMem *umem, size_t offset, size_t size) +{ + size_t s = offset >> umem->page_shift; + size_t e = (offset + size) >> umem->page_shift; + size_t i; + + for (i = s; i < e; i++) { + if (!test_and_set_bit(i, umem->faulted)) { + umem->nsets++; + qemu_madvise(umem->shmem + offset, size, QEMU_MADV_REMOVE); + } + } +} + +bool umem_shmem_finished(const UMem *umem) +{ + return umem->nsets == umem->nbits; +} + +void umem_close_shmem(UMem *umem) +{ + close(umem->shmem_fd); + umem->shmem_fd = -1; +} + +/***************************************************************************/ +/* qemu main loop <-> umem thread communication */ + +static int umem_write_cmd(int fd, uint8_t cmd) +{ + ssize_t size; + + DPRINTF("write cmd %c\n", cmd); + size = qemu_write_full(fd, &cmd, sizeof(cmd)); + if (size == 0) { + if (errno == EPIPE) { + perror("pipe is closed"); + DPRINTF("write cmd %c %d: pipe is closed\n", cmd, errno); + return 0; + } + perror("fail to write to pipe"); + DPRINTF("write cmd %c %d\n", cmd, errno); + return -1; + } + return 0; +} + +static int umem_read_cmd(int fd, uint8_t expect) +{ + ssize_t size; + uint8_t cmd; + + size = qemu_read_full(fd, &cmd, sizeof(cmd)); + if (size == 0) { + DPRINTF("read cmd %c: pipe is closed\n", cmd); + return -1; + } + + DPRINTF("read cmd %c\n", cmd); + if (cmd != expect) { + DPRINTF("cmd %c expect %d\n", cmd, expect); + return -1; + } + return 0; +} + +/* umem thread -> qemu main loop */ +int umem_daemon_ready(int to_qemu_fd) +{ + return umem_write_cmd(to_qemu_fd, UMEM_DAEMON_READY); +} + +int umem_daemon_wait_for_qemu(int from_qemu_fd) +{ + return umem_read_cmd(from_qemu_fd, UMEM_QEMU_READY); +} + +void umem_daemon_quit(QEMUFile *to_qemu) +{ + qemu_put_byte(to_qemu, UMEM_DAEMON_QUIT); +} + +void umem_daemon_error(QEMUFile *to_qemu) +{ + qemu_put_byte(to_qemu, UMEM_DAEMON_ERROR); +} + +/* qemu main loop -> umem thread */ +int umem_qemu_wait_for_daemon(int from_umemd_fd) +{ + return umem_read_cmd(from_umemd_fd, UMEM_DAEMON_READY); +} + +int umem_qemu_ready(int to_umemd_fd) +{ + return umem_write_cmd(to_umemd_fd, UMEM_QEMU_READY); +} + +void umem_qemu_quit(QEMUFile *to_umemd) +{ + qemu_put_byte(to_umemd, UMEM_QEMU_QUIT); +} diff --git a/umem.h b/umem.h new file mode 100644 index 0000000..dbc965c --- /dev/null +++ b/umem.h @@ -0,0 +1,88 @@ +/* + * umem.h: user process backed memory module for postcopy livemigration + * + * Copyright (c) 2011 + * National Institute of Advanced Industrial Science and Technology + * + * https://sites.google.com/site/grivonhome/quick-kvm-migration + * Author: Isaku Yamahata <yamahata at valinux co jp> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef QEMU_UMEM_H +#define QEMU_UMEM_H + +#include "qemu-common.h" + +typedef struct UMemDev UMemDev; + +struct UMem { + void *umem; + int fd; + void *shmem; + int shmem_fd; + uint64_t size; + + /* indexed by host page size */ + int page_shift; + int nbits; + int nsets; + unsigned long *faulted; +}; +typedef struct UMem UMem; + +struct UMemPages { + uint64_t nr; + uint64_t pgoffs[0]; +}; +typedef struct UMemPages UMemPages; + +int umem_new(void *hostp, size_t size, UMem** umemp); +void umem_destroy(UMem *umem); + +/* umem device operations */ +size_t umem_pages_size(uint64_t nr); +int umem_get_page_request(UMem *umem, UMemPages *page_request); +int umem_mark_page_cached(UMem *umem, UMemPages *page_cached); +void umem_unmap(UMem *umem); +void umem_close(UMem *umem); + +/* umem shmem operations */ +int umem_map_shmem(UMem *umem); +void umem_unmap_shmem(UMem *umem); +void umem_remove_shmem(UMem *umem, size_t offset, size_t size); +bool umem_shmem_finished(const UMem *umem); +void umem_close_shmem(UMem *umem); + +/* umem thread -> qemu main loop */ +#define UMEM_DAEMON_READY 'R' +#define UMEM_DAEMON_QUIT 'Q' +#define UMEM_DAEMON_ERROR 'E' + +/* qemu main loop -> umem thread */ +#define UMEM_QEMU_READY 'r' +#define UMEM_QEMU_QUIT 'q' + +/* for umem thread */ +int umem_daemon_ready(int to_qemu_fd); +int umem_daemon_wait_for_qemu(int from_qemu_fd); +void umem_daemon_quit(QEMUFile *to_qemu); +void umem_daemon_error(QEMUFile *to_qemu); + +/* for qemu main loop */ +int umem_qemu_wait_for_daemon(int from_umemd_fd); +int umem_qemu_ready(int to_umemd_fd); +void umem_qemu_quit(QEMUFile *to_umemd); + +#endif /* QEMU_UMEM_H */ -- 1.7.10.4
