Re: [RFC V1 10/12] migration/ram: old host address

[Steven Sistare <steven.sistare@oracle.com>]

On 8/16/2024 1:57 PM, Fabiano Rosas wrote:
> Steve Sistare <steven.sistare@oracle.com> writes:
> 
>> Remember the RAMBlock host address as host_old during migration, for use
>> by CPR.  The iommufd interface to update the virtual address of DMA
>> mappings requires it.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> ---
>>   hw/core/machine.c       | 6 ++++++
>>   include/exec/ramblock.h | 1 +
>>   migration/migration.h   | 2 ++
>>   migration/options.c     | 2 ++
>>   migration/ram.c         | 7 +++++++
>>   5 files changed, 18 insertions(+)
>>
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index 9676953..0ac16b8 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -35,6 +35,12 @@
>>   #include "hw/virtio/virtio-iommu.h"
>>   #include "audio/audio.h"
>>   
>> +/* TBD: register hw_compat_9_1 with machines */
>> +GlobalProperty hw_compat_9_1[] = {
>> +    { "migration", "send-host-old", "off"},
>> +};
>> +const size_t hw_compat_9_1_len = G_N_ELEMENTS(hw_compat_9_1);
>> +
>>   GlobalProperty hw_compat_9_0[] = {
>>       {"arm-cpu", "backcompat-cntfrq", "true" },
>>       {"scsi-disk-base", "migrate-emulated-scsi-request", "false" },
>> diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
>> index 64484cd..8f1c535 100644
>> --- a/include/exec/ramblock.h
>> +++ b/include/exec/ramblock.h
>> @@ -28,6 +28,7 @@ struct RAMBlock {
>>       struct rcu_head rcu;
>>       struct MemoryRegion *mr;
>>       uint8_t *host;
>> +    uint64_t host_old;
>>       uint8_t *colo_cache; /* For colo, VM's ram cache */
>>       ram_addr_t offset;
>>       ram_addr_t used_length;
>> diff --git a/migration/migration.h b/migration/migration.h
>> index 38aa140..b5e3151 100644
>> --- a/migration/migration.h
>> +++ b/migration/migration.h
>> @@ -442,6 +442,8 @@ struct MigrationState {
>>        */
>>       uint8_t clear_bitmap_shift;
>>   
>> +    bool send_host_old;
>> +
>>       /*
>>        * This save hostname when out-going migration starts
>>        */
>> diff --git a/migration/options.c b/migration/options.c
>> index 7526f9f..197cb86 100644
>> --- a/migration/options.c
>> +++ b/migration/options.c
>> @@ -92,6 +92,8 @@ Property migration_properties[] = {
>>                         clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT),
>>       DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState,
>>                        preempt_pre_7_2, false),
>> +    DEFINE_PROP_BOOL("send-host-old", MigrationState,
>> +                     send_host_old, true),
>>   
>>       /* Migration parameters */
>>       DEFINE_PROP_UINT8("x-throttle-trigger-threshold", MigrationState,
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 1e1e05e..8644917 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -3030,6 +3030,9 @@ static int ram_save_setup(QEMUFile *f, void *opaque, Error **errp)
>>               qemu_put_byte(f, strlen(block->idstr));
>>               qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
>>               qemu_put_be64(f, block->used_length);
>> +            if (migrate_get_current()->send_host_old) {
>> +                qemu_put_be64(f, (uint64_t)block->host);
>> +            }
> 
> This requires an update of scripts/analyze-migration.py. Could be done
> on the side.

Indeed.  Thanks.

- Steve

>>               if (migrate_postcopy_ram() &&
>>                   block->page_size != max_hg_page_size) {
>>                   qemu_put_be64(f, block->page_size);
>> @@ -4021,6 +4024,10 @@ static int parse_ramblock(QEMUFile *f, RAMBlock *block, ram_addr_t length)
>>   
>>       assert(block);
>>   
>> +    if (migrate_get_current()->send_host_old) {
>> +        block->host_old = qemu_get_be64(f);
>> +    }
>> +
>>       if (migrate_mapped_ram()) {
>>           parse_ramblock_mapped_ram(f, block, length, &local_err);
>>           if (local_err) {