On Fri, Feb 14, 2025 at 04:44:40PM -0500, Steven Sistare wrote:
> On 2/14/2025 4:21 PM, David Hildenbrand wrote:
> > On 14.02.25 21:12, Steve Sistare wrote:
> > > Unlike cpr-reboot mode, cpr-transfer mode cannot save volatile ram blocks
> > > in the migration stream file and recreate them later, because the physical
> > > memory for the blocks is pinned and registered for vfio. Add a blocker
> > > for volatile ram blocks.
> > >
> > > Also add a blocker for RAM_GUEST_MEMFD. Preserving guest_memfd may be
> > > sufficient for CPR, but it has not been tested yet.
> > >
> > > Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> > > Reviewed-by: Fabiano Rosas <faro...@suse.de>
> > > ---
> > > include/exec/memory.h | 3 +++
> > > include/exec/ramblock.h | 1 +
> > > migration/savevm.c | 2 ++
> > > system/physmem.c | 68
> > > +++++++++++++++++++++++++++++++++++++++++++++++++
> > > 4 files changed, 74 insertions(+)
> > >
> > > diff --git a/include/exec/memory.h b/include/exec/memory.h
> > > index 9f73b59..ea5d33a 100644
> > > --- a/include/exec/memory.h
> > > +++ b/include/exec/memory.h
> > > @@ -3184,6 +3184,9 @@ bool ram_block_discard_is_disabled(void);
> > > */
> > > bool ram_block_discard_is_required(void);
> > > +void ram_block_add_cpr_blocker(RAMBlock *rb, Error **errp);
> > > +void ram_block_del_cpr_blocker(RAMBlock *rb);
> > > +
> > > #endif
> > > #endif
> > > diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
> > > index 0babd10..64484cd 100644
> > > --- a/include/exec/ramblock.h
> > > +++ b/include/exec/ramblock.h
> > > @@ -39,6 +39,7 @@ struct RAMBlock {
> > > /* RCU-enabled, writes protected by the ramlist lock */
> > > QLIST_ENTRY(RAMBlock) next;
> > > QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
> > > + Error *cpr_blocker;
> > > int fd;
> > > uint64_t fd_offset;
> > > int guest_memfd;
> > > diff --git a/migration/savevm.c b/migration/savevm.c
> > > index bc375db..85a3559 100644
> > > --- a/migration/savevm.c
> > > +++ b/migration/savevm.c
> > > @@ -3315,12 +3315,14 @@ void vmstate_register_ram(MemoryRegion *mr,
> > > DeviceState *dev)
> > > qemu_ram_set_idstr(mr->ram_block,
> > > memory_region_name(mr), dev);
> > > qemu_ram_set_migratable(mr->ram_block);
> > > + ram_block_add_cpr_blocker(mr->ram_block, &error_fatal);
> > > }
> > > void vmstate_unregister_ram(MemoryRegion *mr, DeviceState *dev)
> > > {
> > > qemu_ram_unset_idstr(mr->ram_block);
> > > qemu_ram_unset_migratable(mr->ram_block);
> > > + ram_block_del_cpr_blocker(mr->ram_block);
> > > }
> > > void vmstate_register_ram_global(MemoryRegion *mr)
> > > diff --git a/system/physmem.c b/system/physmem.c
> > > index 67c9db9..c416068 100644
> > > --- a/system/physmem.c
> > > +++ b/system/physmem.c
> > > @@ -70,7 +70,10 @@
> > > #include "qemu/pmem.h"
> > > +#include "qapi/qapi-types-migration.h"
> > > +#include "migration/blocker.h"
> > > #include "migration/cpr.h"
> > > +#include "migration/options.h"
> > > #include "migration/vmstate.h"
> > > #include "qemu/range.h"
> > > @@ -1899,6 +1902,14 @@ static void ram_block_add(RAMBlock *new_block,
> > > Error **errp)
> > > qemu_mutex_unlock_ramlist();
> > > goto out_free;
> > > }
> > > +
> > > + error_setg(&new_block->cpr_blocker,
> > > + "Memory region %s uses guest_memfd, "
> > > + "which is not supported with CPR.",
> > > + memory_region_name(new_block->mr));
> > > + migrate_add_blocker_modes(&new_block->cpr_blocker, errp,
> > > + MIG_MODE_CPR_TRANSFER,
> > > + -1);
> > > }
> > > ram_size = (new_block->offset + new_block->max_length) >>
> > > TARGET_PAGE_BITS;
> > > @@ -4059,3 +4070,60 @@ bool ram_block_discard_is_required(void)
> > > return qatomic_read(&ram_block_discard_required_cnt) ||
> > > qatomic_read(&ram_block_coordinated_discard_required_cnt);
> > > }
> > > +
> > > +/*
> > > + * Return true if ram contents would be lost during CPR. Do not exclude
> > > rom,
> > > + * because the rom file could change in new QEMU.
> > > + */
> > > +static bool ram_is_volatile(RAMBlock *rb)
> >
> > Can we call this
> >
> > ram_is_cpr_compatible() / ram_is_cpr_incompatible() or sth. instead?
> >
> > Talking about RAM and "volatile" is misleading, and the function is
> > specific to CPR already (e.g., comment :) ).
>
> Will do, thanks - steve
With that, feel free to take:
Reviewed-by: Peter Xu <pet...@redhat.com>
--
Peter Xu
