On Sun, Jun 30, 2024 at 12:40:25PM -0700, Steve Sistare wrote: > CPR must save state that is needed after QEMU is restarted, when devices > are realized. Thus the extra state cannot be saved in the migration stream, > as objects must already exist before that stream can be loaded. Instead, > define auxilliary state structures and vmstate descriptions, not associated > with any registered object, and serialize the aux state to a cpr-specific > stream in cpr_state_save. Deserialize in cpr_state_load after QEMU > restarts, before devices are realized. > > Provide accessors for clients to register file descriptors for saving. > The mechanism for passing the fd's to the new process will be specific > to each migration mode, and added in subsequent patches. > > Signed-off-by: Steve Sistare <steven.sist...@oracle.com> > --- > include/migration/cpr.h | 21 ++++++ > migration/cpr.c | 188 > ++++++++++++++++++++++++++++++++++++++++++++++++ > migration/meson.build | 1 + > migration/migration.c | 6 ++ > migration/trace-events | 5 ++ > system/vl.c | 3 + > 6 files changed, 224 insertions(+) > create mode 100644 include/migration/cpr.h > create mode 100644 migration/cpr.c > > diff --git a/include/migration/cpr.h b/include/migration/cpr.h > new file mode 100644 > index 0000000..8e7e705 > --- /dev/null > +++ b/include/migration/cpr.h > @@ -0,0 +1,21 @@ > +/* > + * Copyright (c) 2021, 2024 Oracle and/or its affiliates. > + * > + * This work is licensed under the terms of the GNU GPL, version 2 or later. > + * See the COPYING file in the top-level directory. > + */ > + > +#ifndef MIGRATION_CPR_H > +#define MIGRATION_CPR_H > + > +typedef int (*cpr_walk_fd_cb)(int fd); > +void cpr_save_fd(const char *name, int id, int fd); > +void cpr_delete_fd(const char *name, int id); > +int cpr_find_fd(const char *name, int id); > +int cpr_walk_fd(cpr_walk_fd_cb cb); > +void cpr_resave_fd(const char *name, int id, int fd); > + > +int cpr_state_save(Error **errp); > +int cpr_state_load(Error **errp); > + > +#endif > diff --git a/migration/cpr.c b/migration/cpr.c > new file mode 100644 > index 0000000..313e74e > --- /dev/null > +++ b/migration/cpr.c > @@ -0,0 +1,188 @@ > +/* > + * Copyright (c) 2021-2024 Oracle and/or its affiliates. > + * > + * This work is licensed under the terms of the GNU GPL, version 2 or later. > + * See the COPYING file in the top-level directory. > + */ > + > +#include "qemu/osdep.h" > +#include "qapi/error.h" > +#include "migration/cpr.h" > +#include "migration/misc.h" > +#include "migration/qemu-file.h" > +#include "migration/savevm.h" > +#include "migration/vmstate.h" > +#include "sysemu/runstate.h" > +#include "trace.h" > + > +/*************************************************************************/ > +/* cpr state container for all information to be saved. */ > + > +typedef QLIST_HEAD(CprFdList, CprFd) CprFdList; > + > +typedef struct CprState { > + CprFdList fds; > +} CprState; > + > +static CprState cpr_state; > + > +/****************************************************************************/ > + > +typedef struct CprFd { > + char *name; > + unsigned int namelen; > + int id; > + int fd;
[1] > + QLIST_ENTRY(CprFd) next; > +} CprFd; > + > +static const VMStateDescription vmstate_cpr_fd = { > + .name = "cpr fd", > + .version_id = 1, > + .minimum_version_id = 1, > + .fields = (VMStateField[]) { > + VMSTATE_UINT32(namelen, CprFd), > + VMSTATE_VBUFFER_ALLOC_UINT32(name, CprFd, 0, NULL, namelen), > + VMSTATE_INT32(id, CprFd), > + VMSTATE_INT32(fd, CprFd), > + VMSTATE_END_OF_LIST() > + } > +}; > + > +void cpr_save_fd(const char *name, int id, int fd) > +{ > + CprFd *elem = g_new0(CprFd, 1); > + > + trace_cpr_save_fd(name, id, fd); > + elem->name = g_strdup(name); > + elem->namelen = strlen(name) + 1; > + elem->id = id; > + elem->fd = fd; > + QLIST_INSERT_HEAD(&cpr_state.fds, elem, next); > +} > + > +static CprFd *find_fd(CprFdList *head, const char *name, int id) > +{ > + CprFd *elem; > + > + QLIST_FOREACH(elem, head, next) { > + if (!strcmp(elem->name, name) && elem->id == id) { > + return elem; > + } > + } > + return NULL; > +} > + > +void cpr_delete_fd(const char *name, int id) > +{ > + CprFd *elem = find_fd(&cpr_state.fds, name, id); > + > + if (elem) { > + QLIST_REMOVE(elem, next); > + g_free(elem->name); > + g_free(elem); > + } > + > + trace_cpr_delete_fd(name, id); > +} > + > +int cpr_find_fd(const char *name, int id) > +{ > + CprFd *elem = find_fd(&cpr_state.fds, name, id); > + int fd = elem ? elem->fd : -1; > + > + trace_cpr_find_fd(name, id, fd); > + return fd; > +} > + > +int cpr_walk_fd(cpr_walk_fd_cb cb) > +{ > + CprFd *elem; > + > + QLIST_FOREACH(elem, &cpr_state.fds, next) { > + if (elem->fd >= 0 && cb(elem->fd)) { > + return 1; > + } > + } > + return 0; > +} > + > +void cpr_resave_fd(const char *name, int id, int fd) > +{ > + CprFd *elem = find_fd(&cpr_state.fds, name, id); > + int old_fd = elem ? elem->fd : -1; > + > + if (old_fd < 0) { > + cpr_save_fd(name, id, fd); I don't think I know well on when old_fd<0 would happen yet, as this series doesn't look like to use this function at all. From that POV, maybe nice to add a comment above [1] for "fd" field. Meanwhile, do we need to remove the old_fd<0 element here, or is it intended to keep that and the new CprFD? > + } else if (old_fd != fd) { > + error_setg(&error_fatal, > + "internal error: cpr fd '%s' id %d value %d " > + "already saved with a different value %d", > + name, id, fd, old_fd); > + } > +} > +/*************************************************************************/ > +#define CPR_STATE "CprState" > + > +static const VMStateDescription vmstate_cpr_state = { > + .name = CPR_STATE, > + .version_id = 1, > + .minimum_version_id = 1, > + .fields = (VMStateField[]) { > + VMSTATE_QLIST_V(fds, CprState, 1, vmstate_cpr_fd, CprFd, next), > + VMSTATE_END_OF_LIST() > + } > +}; > +/*************************************************************************/ > + > +int cpr_state_save(Error **errp) > +{ > + int ret; > + QEMUFile *f; > + > + /* set f based on mode in a later patch in this series */ > + return 0; > + > + qemu_put_be32(f, QEMU_VM_FILE_MAGIC); > + qemu_put_be32(f, QEMU_VM_FILE_VERSION); Having magic/version makes sense to me, though I'd suggest we use CPR new magic/versions, so that if we see an binary dump we know what it is, and we don't mixup a CPR image against a migration stream image. > + > + ret = vmstate_save_state(f, &vmstate_cpr_state, &cpr_state, 0); s/0/NULL/ > + if (ret) { > + error_setg(errp, "vmstate_save_state error %d", ret); > + } Can consider using vmstate_save_state_with_err(). > + > + qemu_fclose(f); > + return ret; > +} > + > +int cpr_state_load(Error **errp) > +{ > + int ret; > + uint32_t v; > + QEMUFile *f; > + > + /* set f based on mode in a later patch in this series */ > + return 0; > + > + v = qemu_get_be32(f); > + if (v != QEMU_VM_FILE_MAGIC) { > + error_setg(errp, "Not a migration stream (bad magic %x)", v); > + qemu_fclose(f); > + return -EINVAL; > + } > + v = qemu_get_be32(f); > + if (v != QEMU_VM_FILE_VERSION) { > + error_setg(errp, "Unsupported migration stream version %d", v); > + qemu_fclose(f); > + return -ENOTSUP; > + } > + > + ret = vmstate_load_state(f, &vmstate_cpr_state, &cpr_state, 1); > + if (ret) { > + error_setg(errp, "vmstate_load_state error %d", ret); > + } Simiarly, can use vmstate_save_state_with_err(). > + > + qemu_fclose(f); > + return ret; > +} > + > diff --git a/migration/meson.build b/migration/meson.build > index 5ce2acb4..87feb4c 100644 > --- a/migration/meson.build > +++ b/migration/meson.build > @@ -13,6 +13,7 @@ system_ss.add(files( > 'block-dirty-bitmap.c', > 'channel.c', > 'channel-block.c', > + 'cpr.c', > 'dirtyrate.c', > 'exec.c', > 'fd.c', > diff --git a/migration/migration.c b/migration/migration.c > index 3dea06d..e394ad7 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -27,6 +27,7 @@ > #include "sysemu/cpu-throttle.h" > #include "rdma.h" > #include "ram.h" > +#include "migration/cpr.h" > #include "migration/global_state.h" > #include "migration/misc.h" > #include "migration.h" > @@ -2118,6 +2119,10 @@ void qmp_migrate(const char *uri, bool has_channels, > } > } > > + if (cpr_state_save(&local_err)) { > + goto out; > + } > + > if (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) { > SocketAddress *saddr = &addr->u.socket; > if (saddr->type == SOCKET_ADDRESS_TYPE_INET || > @@ -2142,6 +2147,7 @@ void qmp_migrate(const char *uri, bool has_channels, > MIGRATION_STATUS_FAILED); > } > > +out: > if (local_err) { > if (!resume_requested) { > yank_unregister_instance(MIGRATION_YANK_INSTANCE); > diff --git a/migration/trace-events b/migration/trace-events > index 0b7c332..173f2c0 100644 > --- a/migration/trace-events > +++ b/migration/trace-events > @@ -340,6 +340,11 @@ colo_receive_message(const char *msg) "Receive '%s' > message" > # colo-failover.c > colo_failover_set_state(const char *new_state) "new state %s" > > +# cpr.c > +cpr_save_fd(const char *name, int id, int fd) "%s, id %d, fd %d" > +cpr_delete_fd(const char *name, int id) "%s, id %d" > +cpr_find_fd(const char *name, int id, int fd) "%s, id %d returns %d" > + > # block-dirty-bitmap.c > send_bitmap_header_enter(void) "" > send_bitmap_bits(uint32_t flags, uint64_t start_sector, uint32_t nr_sectors, > uint64_t data_size) "flags: 0x%x, start_sector: %" PRIu64 ", nr_sectors: %" > PRIu32 ", data_size: %" PRIu64 > diff --git a/system/vl.c b/system/vl.c > index 03951be..6521ee3 100644 > --- a/system/vl.c > +++ b/system/vl.c > @@ -77,6 +77,7 @@ > #include "hw/block/block.h" > #include "hw/i386/x86.h" > #include "hw/i386/pc.h" > +#include "migration/cpr.h" > #include "migration/misc.h" > #include "migration/snapshot.h" > #include "sysemu/tpm.h" > @@ -3713,6 +3714,8 @@ void qemu_init(int argc, char **argv) > > qemu_create_machine(machine_opts_dict); > > + cpr_state_load(&error_fatal); Might be good to add a rich comment here explaining the decision on why loading here; I think most of the tricks lie here. E.g., it needs to be before XXX and it needs to be after YYY. Thanks, > + > suspend_mux_open(); > > qemu_disable_default_devices(); > -- > 1.8.3.1 > -- Peter Xu