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Violators will be prosecuted for from ; Wed, 26 Apr 2017 07:06:07 -0300 References: <20170424220828.1472-1-danielhb@linux.vnet.ibm.com> <20170424220828.1472-2-danielhb@linux.vnet.ibm.com> <149315920012.25359.9652547359202749316@loki> From: Daniel Henrique Barboza Date: Wed, 26 Apr 2017 07:05:58 -0300 MIME-Version: 1.0 In-Reply-To: <149315920012.25359.9652547359202749316@loki> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Message-Id: <861bf961-ac4b-ec03-f98e-3a15cc0454b4@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 1/4] migration: alternative way to set instance_id in SaveStateEntry List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth , qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au On 04/25/2017 07:26 PM, Michael Roth wrote: > Quoting Daniel Henrique Barboza (2017-04-24 17:08:25) >> From: Jianjun Duan >> >> In QOM (QEMU Object Model) migrated objects are identified with instance_id >> which is calculated automatically using their path in the QOM composition >> tree. For some objects, this path could change from source to target in >> migration. To migrate such objects, we need to make sure the instance_id does >> not change from source to target. We add a hook in DeviceClass to do customized >> instance_id calculation in such cases. > When I tried to pluck a subset of these patches for another series it > was noticed that we don't actually need this patch anymore: > > https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05475.html > > hw/ppc/spapr_iommu.c already implements an approach for registering DRCs > that would work for our case as well since DRCs are bus-less and do not sit > on a BusClass that implements bc->get_dev_path, so using > vmstate_register(DEVICE(drc), drck->get_index(drc), ...) will work in > the same way this patch expects it to. Good to know. I'll see if I can get rid of this whole patch and use this approach instead. > >> As a result, in these cases compat will not be set in the concerned >> SaveStateEntry. This will prevent the inconsistent idstr to be sent over in >> migration. We could have set alias_id in a similar way. But that will be >> overloading the purpose of alias_id. >> >> The first application will be setting instance_id for pseries DRC objects using >> its unique index. Doing this makes the instance_id of DRC to be consistent >> across migration and supports flexible management of DRC objects in migration. >> >> Signed-off-by: Jianjun Duan >> Signed-off-by: Daniel Henrique Barboza >> --- >> include/hw/qdev-core.h | 6 ++++++ >> migration/savevm.c | 6 ++++++ >> 2 files changed, 12 insertions(+) >> >> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h >> index 4bf86b0..9b3914c 100644 >> --- a/include/hw/qdev-core.h >> +++ b/include/hw/qdev-core.h >> @@ -127,6 +127,12 @@ typedef struct DeviceClass { >> qdev_initfn init; /* TODO remove, once users are converted to realize */ >> qdev_event exit; /* TODO remove, once users are converted to unrealize */ >> const char *bus_type; >> + >> + /* When this field is set, qemu will use it to get an unique instance_id >> + * instead of calculating an auto idstr and instance_id for the relevant >> + * SaveStateEntry >> + */ >> + int (*dev_get_instance_id)(DeviceState *dev); >> } DeviceClass; >> >> typedef struct NamedGPIOList NamedGPIOList; >> diff --git a/migration/savevm.c b/migration/savevm.c >> index 03ae1bd..5d8135f 100644 >> --- a/migration/savevm.c >> +++ b/migration/savevm.c >> @@ -606,6 +606,9 @@ int register_savevm_live(DeviceState *dev, >> calculate_compat_instance_id(idstr) : instance_id; >> instance_id = -1; >> } >> + if (DEVICE_GET_CLASS(dev)->dev_get_instance_id) { >> + instance_id = DEVICE_GET_CLASS(dev)->dev_get_instance_id(dev); >> + } >> } >> pstrcat(se->idstr, sizeof(se->idstr), idstr); >> >> @@ -696,6 +699,9 @@ int vmstate_register_with_alias_id(DeviceState *dev, int instance_id, >> calculate_compat_instance_id(vmsd->name) : instance_id; >> instance_id = -1; >> } >> + if (DEVICE_GET_CLASS(dev)->dev_get_instance_id) { >> + instance_id = DEVICE_GET_CLASS(dev)->dev_get_instance_id(dev); >> + } >> } >> pstrcat(se->idstr, sizeof(se->idstr), vmsd->name); >> >> -- >> 2.9.3 >> >> >