From eb59db53a4f23420f127ec7aad2a672f787df697 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Thu, 5 Nov 2015 18:10:55 +0000 Subject: postcopy: OS support test Provide a check to see if the OS we're running on has all the bits needed for postcopy. Creates postcopy-ram.c which will get most of the other helpers we need. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Amit Shah Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/Makefile.objs | 2 +- migration/postcopy-ram.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++ migration/savevm.c | 5 ++ 3 files changed, 163 insertions(+), 1 deletion(-) create mode 100644 migration/postcopy-ram.c (limited to 'migration') diff --git a/migration/Makefile.objs b/migration/Makefile.objs index d929e969ae..0cac6d707a 100644 --- a/migration/Makefile.objs +++ b/migration/Makefile.objs @@ -1,7 +1,7 @@ common-obj-y += migration.o tcp.o common-obj-y += vmstate.o common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o -common-obj-y += xbzrle.o +common-obj-y += xbzrle.o postcopy-ram.o common-obj-$(CONFIG_RDMA) += rdma.o common-obj-$(CONFIG_POSIX) += exec.o unix.o fd.o diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c new file mode 100644 index 0000000000..cdd0168dbb --- /dev/null +++ b/migration/postcopy-ram.c @@ -0,0 +1,157 @@ +/* + * Postcopy migration for RAM + * + * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Dave Gilbert + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +/* + * Postcopy is a migration technique where the execution flips from the + * source to the destination before all the data has been copied. + */ + +#include +#include +#include + +#include "qemu-common.h" +#include "migration/migration.h" +#include "migration/postcopy-ram.h" +#include "sysemu/sysemu.h" +#include "qemu/error-report.h" +#include "trace.h" + +/* Postcopy needs to detect accesses to pages that haven't yet been copied + * across, and efficiently map new pages in, the techniques for doing this + * are target OS specific. + */ +#if defined(__linux__) + +#include +#include +#include +#include +#include /* for __u64 */ +#endif + +#if defined(__linux__) && defined(__NR_userfaultfd) +#include + +static bool ufd_version_check(int ufd) +{ + struct uffdio_api api_struct; + uint64_t ioctl_mask; + + api_struct.api = UFFD_API; + api_struct.features = 0; + if (ioctl(ufd, UFFDIO_API, &api_struct)) { + error_report("postcopy_ram_supported_by_host: UFFDIO_API failed: %s", + strerror(errno)); + return false; + } + + ioctl_mask = (__u64)1 << _UFFDIO_REGISTER | + (__u64)1 << _UFFDIO_UNREGISTER; + if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) { + error_report("Missing userfault features: %" PRIx64, + (uint64_t)(~api_struct.ioctls & ioctl_mask)); + return false; + } + + return true; +} + +bool postcopy_ram_supported_by_host(void) +{ + long pagesize = getpagesize(); + int ufd = -1; + bool ret = false; /* Error unless we change it */ + void *testarea = NULL; + struct uffdio_register reg_struct; + struct uffdio_range range_struct; + uint64_t feature_mask; + + if ((1ul << qemu_target_page_bits()) > pagesize) { + error_report("Target page size bigger than host page size"); + goto out; + } + + ufd = syscall(__NR_userfaultfd, O_CLOEXEC); + if (ufd == -1) { + error_report("%s: userfaultfd not available: %s", __func__, + strerror(errno)); + goto out; + } + + /* Version and features check */ + if (!ufd_version_check(ufd)) { + goto out; + } + + /* + * We need to check that the ops we need are supported on anon memory + * To do that we need to register a chunk and see the flags that + * are returned. + */ + testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | + MAP_ANONYMOUS, -1, 0); + if (testarea == MAP_FAILED) { + error_report("%s: Failed to map test area: %s", __func__, + strerror(errno)); + goto out; + } + g_assert(((size_t)testarea & (pagesize-1)) == 0); + + reg_struct.range.start = (uintptr_t)testarea; + reg_struct.range.len = pagesize; + reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; + + if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) { + error_report("%s userfault register: %s", __func__, strerror(errno)); + goto out; + } + + range_struct.start = (uintptr_t)testarea; + range_struct.len = pagesize; + if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) { + error_report("%s userfault unregister: %s", __func__, strerror(errno)); + goto out; + } + + feature_mask = (__u64)1 << _UFFDIO_WAKE | + (__u64)1 << _UFFDIO_COPY | + (__u64)1 << _UFFDIO_ZEROPAGE; + if ((reg_struct.ioctls & feature_mask) != feature_mask) { + error_report("Missing userfault map features: %" PRIx64, + (uint64_t)(~reg_struct.ioctls & feature_mask)); + goto out; + } + + /* Success! */ + ret = true; +out: + if (testarea) { + munmap(testarea, pagesize); + } + if (ufd != -1) { + close(ufd); + } + return ret; +} + +#else +/* No target OS support, stubs just fail */ +bool postcopy_ram_supported_by_host(void) +{ + error_report("%s: No OS support", __func__); + return false; +} + +#endif + diff --git a/migration/savevm.c b/migration/savevm.c index 7467dc0e7b..0e48a919e9 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -37,6 +37,7 @@ #include "qemu/timer.h" #include "audio/audio.h" #include "migration/migration.h" +#include "migration/postcopy-ram.h" #include "qapi/qmp/qerror.h" #include "qemu/error-report.h" #include "qemu/sockets.h" @@ -1205,6 +1206,10 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis) return -1; } + if (!postcopy_ram_supported_by_host()) { + return -1; + } + remote_hps = qemu_get_be64(mis->from_src_file); if (remote_hps != getpagesize()) { /* -- cgit v1.2.3