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Re: [Qemu-ppc] [QEMU RFC PATCH v3 4/6] Migration: migrate QTAILQ
From: |
Jianjun Duan |
Subject: |
Re: [Qemu-ppc] [QEMU RFC PATCH v3 4/6] Migration: migrate QTAILQ |
Date: |
Tue, 31 May 2016 14:53:17 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
On 05/31/2016 12:54 PM, Paolo Bonzini wrote:
>
>
> ----- Original Message -----
>> From: "Jianjun Duan" <address@hidden>
>> To: address@hidden
>> Cc: address@hidden, address@hidden, address@hidden, "peter maydell"
>> <address@hidden>,
>> address@hidden, address@hidden, address@hidden, address@hidden,
>> address@hidden,
>> address@hidden, "amit shah" <address@hidden>, address@hidden,
>> address@hidden, address@hidden,
>> address@hidden, "leon alrae" <address@hidden>, address@hidden, "mark
>> cave-ayland"
>> <address@hidden>, address@hidden
>> Sent: Tuesday, May 31, 2016 8:02:42 PM
>> Subject: [QEMU RFC PATCH v3 4/6] Migration: migrate QTAILQ
>>
>> Currently we cannot directly transfer a QTAILQ instance because of the
>> limitation in the migration code. Here we introduce an approach to
>> transfer such structures. In our approach such a structure is tagged
>> with VMS_CSTM. We then modified vmstate_save_state and vmstate_load_state
>> so that when VMS_CSTM is encountered, put and get from VMStateInfo are
>> called respectively. This approach will be used to transfer pending_events
>> and ccs_list in spapr state.
>>
>> We also create some macros in qemu/queue.h to access a QTAILQ using pointer
>> arithmetic. This ensures that we do not depend on the implementation
>> details about QTAILQ in the migration code.
>>
>> Signed-off-by: Jianjun Duan <address@hidden>
>> ---
>> include/migration/vmstate.h | 22 +++++++++++++
>> include/qemu/queue.h | 32 ++++++++++++++++++
>> migration/vmstate.c | 79
>> +++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 133 insertions(+)
>>
>> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
>> index 56a4171..da4ef7f 100644
>> --- a/include/migration/vmstate.h
>> +++ b/include/migration/vmstate.h
>> @@ -185,6 +185,8 @@ enum VMStateFlags {
>> * to determine the number of entries in the array. Only valid in
>> * combination with one of VMS_VARRAY*. */
>> VMS_MULTIPLY_ELEMENTS = 0x4000,
>> + /* For fields which need customized handling, such as QTAILQ in
>> queue.h*/
>> + VMS_CSTM = 0x8000,
>
> Please call this VMS_LINKED. It can be adapted to other data
> structures in qemu/queue.h if there is a need later on.
>
>> };
>>
>> struct VMStateField {
>> @@ -245,6 +247,7 @@ extern const VMStateInfo vmstate_info_timer;
>> extern const VMStateInfo vmstate_info_buffer;
>> extern const VMStateInfo vmstate_info_unused_buffer;
>> extern const VMStateInfo vmstate_info_bitmap;
>> +extern const VMStateInfo vmstate_info_qtailq;
>>
>> #define type_check_2darray(t1,t2,n,m) ((t1(*)[n][m])0 - (t2*)0)
>> #define type_check_array(t1,t2,n) ((t1(*)[n])0 - (t2*)0)
>> @@ -656,6 +659,25 @@ extern const VMStateInfo vmstate_info_bitmap;
>> .offset = offsetof(_state, _field), \
>> }
>>
>> +/* For QTAILQ that need customized handling
>> + * _type: type of QTAILQ element
>> + * _next: name of QTAILQ entry field in QTAILQ element
>> + * _vmsd: VMSD for QTAILQ element
>> + * size: size of QTAILQ element
>> + * start: offset of QTAILQ entry in QTAILQ element
>> + */
>> +#define VMSTATE_QTAILQ_V(_field, _state, _version, _vmsd, _type, _next) \
>> +{ \
>> + .name = (stringify(_field)), \
>> + .version_id = (_version), \
>> + .vmsd = &(_vmsd), \
>> + .size = sizeof(_type), \
>> + .info = &vmstate_info_qtailq, \
>> + .flags = VMS_CSTM, \
>> + .offset = offsetof(_state, _field), \
>> + .start = offsetof(_type, _next), \
>> +}
>> +
>> /* _f : field name
>> _f_n : num of elements field_name
>> _n : num of elements
>> diff --git a/include/qemu/queue.h b/include/qemu/queue.h
>> index f781aa2..003e368 100644
>> --- a/include/qemu/queue.h
>> +++ b/include/qemu/queue.h
>> @@ -437,3 +437,35 @@ struct {
>> \
>> (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
>>
>> #endif /* !QEMU_SYS_QUEUE_H_ */
>> +
>> +/*
>> + * Offsets of layout of a tail queue head.
>> + */
>> +#define QTAILQ_FIRST_OFFSET 0
>> +#define QTAILQ_LAST_OFFSET (sizeof(void *))
>> +
>> +/*
>> + * Offsets of layout of a tail queue element.
>> + */
>> +#define QTAILQ_NEXT_OFFSET 0
>> +#define QTAILQ_PREV_OFFSET (sizeof(void *))
>> +
>> +/*
>> + * Tail queue tranversal using pointer arithmetic.
>> + */
>> +#define QTAILQ_RAW_FOREACH(elm, head, entry)
>> \
>> + for ((elm) = *((void **) ((char *) (head) + QTAILQ_FIRST_OFFSET));
>> \
>> + (elm);
>> \
>> + (elm) =
>> \
>> + *((void **) ((char *) (elm) + (entry) +
>> QTAILQ_NEXT_OFFSET)))
>> +/*
>> + * Tail queue insertion using pointer arithmetic.
>> + */
>> +#define QTAILQ_RAW_INSERT_TAIL(head, elm, entry) do {
>> \
>> + *((void **) ((char *) (elm) + (entry) + QTAILQ_NEXT_OFFSET)) = NULL;
>> \
>> + *((void **) ((char *) (elm) + (entry) + QTAILQ_PREV_OFFSET)) =
>> \
>> + *((void **) ((char *) (head) +QTAILQ_LAST_OFFSET));
>> \
>> + **((void ***)((char *) (head) +QTAILQ_LAST_OFFSET)) = (elm);
>> \
>> + *((void **) ((char *) (head) + QTAILQ_LAST_OFFSET)) =
>> \
>> + (void *) ((char *) (elm) + (entry) + QTAILQ_NEXT_OFFSET);
>> \
>> +} while (/*CONSTCOND*/0)
>> diff --git a/migration/vmstate.c b/migration/vmstate.c
>> index 644ba1f..ff56650 100644
>> --- a/migration/vmstate.c
>> +++ b/migration/vmstate.c
>> @@ -5,7 +5,9 @@
>> #include "migration/vmstate.h"
>> #include "qemu/bitops.h"
>> #include "qemu/error-report.h"
>> +#include "qemu/queue.h"
>> #include "trace.h"
>> +#include "migration/qjson.h"
>>
>> static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription
>> *vmsd,
>> void *opaque, QJSON *vmdesc);
>> @@ -120,6 +122,8 @@ int vmstate_load_state(QEMUFile *f, const
>> VMStateDescription *vmsd,
>> if (field->flags & VMS_STRUCT) {
>> ret = vmstate_load_state(f, field->vmsd, addr,
>> field->vmsd->version_id);
>> + } else if (field->flags & VMS_CSTM) {
>> + ret = field->info->get(f, addr, size, field);
>> } else {
>> ret = field->info->get(f, addr, size, NULL);
>>
>> @@ -192,6 +196,8 @@ static const char *vmfield_get_type_name(VMStateField
>> *field)
>>
>> if (field->flags & VMS_STRUCT) {
>> type = "struct";
>> + } else if (field->flags & VMS_CSTM) {
>> + type = "customized";
>> } else if (field->info->name) {
>> type = field->info->name;
>> }
>> @@ -326,6 +332,8 @@ void vmstate_save_state(QEMUFile *f, const
>> VMStateDescription *vmsd,
>> }
>> if (field->flags & VMS_STRUCT) {
>> vmstate_save_state(f, field->vmsd, addr, vmdesc_loop);
>> + } else if (field->flags & VMS_CSTM) {
>> + field->info->put(f, addr, size, field, vmdesc_loop);
>> } else {
>> field->info->put(f, addr, size, NULL, NULL);
>> }
>> @@ -938,3 +946,74 @@ const VMStateInfo vmstate_info_bitmap = {
>> .get = get_bitmap,
>> .put = put_bitmap,
>> };
>> +
>> +/*get for QTAILQ */
>> +static int get_qtailq(QEMUFile *f, void *pv, size_t unused_size,
>> + VMStateField *field)
>> +{
>> + bool link;
>> + int ret = 0;
>> + const VMStateDescription *vmsd = field->vmsd;
>> + size_t size = field->size;
>> + size_t entry = field->start;
>> + int version_id = field->version_id;
>> + void *elm;
>> +
>> + trace_vmstate_load_state(vmsd->name, version_id);
>> + if (version_id > vmsd->version_id) {
>> + trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL);
>> + return -EINVAL;
>> + }
>> + if (version_id < vmsd->minimum_version_id) {
>> + trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
>> + return -EINVAL;
>> + }
>> +
>> + while (true) {
>> + vmstate_info_bool.get(f, &link, sizeof(bool), NULL);
>
> You can use qemu_get_byte here, and likewise qemu_put_byte below in
> put_qtailq.
qemu_get/put is indeed better choice.
>
>> + if (!link) {
>> + break;
>> + }
>> +
>> + elm = g_malloc(size);
>> + ret = vmstate_load_state(f, vmsd, elm, version_id);
>> + if (ret) {
>> + return ret;
>> + }
>> + QTAILQ_RAW_INSERT_TAIL(pv, elm, entry);
>> + }
>> +
>> + trace_vmstate_load_state_end(vmsd->name, "end", ret);
>> + return ret;
>> +}
>> +
>> +/* put for QTAILQ */
>> +static void put_qtailq(QEMUFile *f, void *pv, size_t unused_size,
>> + VMStateField *field, QJSON *vmdesc)
>> +{
>> + bool link = true;
>> + const VMStateDescription *vmsd = field->vmsd;
>> + size_t entry = field->start;
>> + void *elm;
>> +
>> + if (vmdesc) {
>> + json_prop_str(vmdesc, "vmsd_name", vmsd->name);
>> + json_prop_int(vmdesc, "version", vmsd->version_id);
>> + json_start_array(vmdesc, "fields");
>
> You need to store the fields exactly once here, even if there are
> 0 or >1 elements.
>
Do you mean the json entries? I think it is already doing that.
> Otherwise looks great now!
>
> Paolo
>
>> + }
>> +
>> + QTAILQ_RAW_FOREACH(elm, pv, entry) {
>> + vmstate_info_bool.put(f, &link, sizeof(bool), NULL, NULL);
>> + vmstate_save_state(f, vmsd, elm, vmdesc);
>> + }
>> + link = false;
>> + vmstate_info_bool.put(f, &link, sizeof(bool), NULL, NULL);
>> + if (vmdesc) {
>> + json_end_array(vmdesc);
>> + }
>> +}
>> +const VMStateInfo vmstate_info_qtailq = {
>> + .name = "qtailq",
>> + .get = get_qtailq,
>> + .put = put_qtailq,
>> +};
>> --
>> 1.9.1
>>
>>
>
Thanks,
Jianjun
- [Qemu-ppc] [QEMU RFC PATCH v3 0/6]Migration: ensure hotplug and migration work together, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 1/6] Migration: Defined VMStateDescription struct for spapr_drc, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 2/6] vmstate: Define VARRAY with VMS_ALLOC, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 3/6] Migration: extend VMStateInfo, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 4/6] Migration: migrate QTAILQ, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 6/6] Migration: migrate pending_events of spapr state, Jianjun Duan, 2016/05/31
- [Qemu-ppc] [QEMU RFC PATCH v3 5/6] Migration: migrate ccs_list in spapr state, Jianjun Duan, 2016/05/31