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Sun, 18 Oct 2020 17:40:44 +0000 Subject: Re: [PATCH v26 07/17] vfio: Register SaveVMHandlers for VFIO device To: Alex Williamson References: <1600817059-26721-1-git-send-email-kwankhede@nvidia.com> <1600817059-26721-8-git-send-email-kwankhede@nvidia.com> <20200925142046.7c9eca89@x1.home> X-Nvconfidentiality: public From: Kirti Wankhede Message-ID: <9e965cfb-f5f9-aa88-32c8-8623ee917529@nvidia.com> Date: Sun, 18 Oct 2020 23:10:40 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200925142046.7c9eca89@x1.home> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1603042846; bh=EDJ/D6M5/4FSlcAnB1s3zU9GibIQUX4lGrRTwwnjp2E=; h=Subject:To:CC:References:X-Nvconfidentiality:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=RVUJ0i/jhkRXpFWv91ymSM2Ab2PLyNBRJTHuPluGvxKNs7vdYH2gFGX4UihGHFa9Y U+RU5ktuVCYPIuNbP+m2m2b7qCqD+vKPTYwRTVGGMGx0LFkj2zPWAFL0goGKgY4kyr WaZ3i4rbmSfjUieIQa/dQswWYghP3jZraImsNi4vkRBsZ8lPvBf98gZiXZvYjawzYx ajNDP7oRWLQ5xe2bNmN8JNoZffgsLxUZFYPkvo4M75SIzZDhvhE1jEcF9ywOqcZwoz eUH/APwwKEkOVtUbyMLOqDQ7hc/ZyJAFPjtDoH0mWA0uukdD9TaFzAbDp9Q7u108Nt cQxXYF6g9t1fg== Received-SPF: pass client-ip=216.228.121.65; envelope-from=kwankhede@nvidia.com; helo=hqnvemgate26.nvidia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/18 13:40:59 X-ACL-Warn: Detected OS = Windows 7 or 8 [fuzzy] X-Spam_score_int: -70 X-Spam_score: -7.1 X-Spam_bar: ------- X-Spam_report: (-7.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: cohuck@redhat.com, cjia@nvidia.com, aik@ozlabs.ru, Zhengxiao.zx@Alibaba-inc.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, peterx@redhat.com, eauger@redhat.com, yi.l.liu@intel.com, quintela@redhat.com, ziye.yang@intel.com, armbru@redhat.com, mlevitsk@redhat.com, pasic@linux.ibm.com, felipe@nutanix.com, zhi.a.wang@intel.com, kevin.tian@intel.com, yan.y.zhao@intel.com, dgilbert@redhat.com, changpeng.liu@intel.com, eskultet@redhat.com, Ken.Xue@amd.com, jonathan.davies@nutanix.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/26/2020 1:50 AM, Alex Williamson wrote: > On Wed, 23 Sep 2020 04:54:09 +0530 > Kirti Wankhede wrote: > >> Define flags to be used as delimeter in migration file stream. >> Added .save_setup and .save_cleanup functions. Mapped & unmapped migration >> region from these functions at source during saving or pre-copy phase. >> Set VFIO device state depending on VM's state. During live migration, VM is >> running when .save_setup is called, _SAVING | _RUNNING state is set for VFIO >> device. During save-restore, VM is paused, _SAVING state is set for VFIO device. >> >> Signed-off-by: Kirti Wankhede >> Reviewed-by: Neo Jia >> --- >> hw/vfio/migration.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++ >> hw/vfio/trace-events | 2 ++ >> 2 files changed, 93 insertions(+) >> >> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c >> index f650fe9fc3c8..8e8adaa25779 100644 >> --- a/hw/vfio/migration.c >> +++ b/hw/vfio/migration.c >> @@ -8,12 +8,15 @@ >> */ >> >> #include "qemu/osdep.h" >> +#include "qemu/main-loop.h" >> +#include "qemu/cutils.h" >> #include >> >> #include "sysemu/runstate.h" >> #include "hw/vfio/vfio-common.h" >> #include "cpu.h" >> #include "migration/migration.h" >> +#include "migration/vmstate.h" >> #include "migration/qemu-file.h" >> #include "migration/register.h" >> #include "migration/blocker.h" >> @@ -25,6 +28,17 @@ >> #include "trace.h" >> #include "hw/hw.h" >> >> +/* >> + * Flags used as delimiter: >> + * 0xffffffff => MSB 32-bit all 1s >> + * 0xef10 => emulated (virtual) function IO >> + * 0x0000 => 16-bits reserved for flags >> + */ >> +#define VFIO_MIG_FLAG_END_OF_STATE (0xffffffffef100001ULL) >> +#define VFIO_MIG_FLAG_DEV_CONFIG_STATE (0xffffffffef100002ULL) >> +#define VFIO_MIG_FLAG_DEV_SETUP_STATE (0xffffffffef100003ULL) >> +#define VFIO_MIG_FLAG_DEV_DATA_STATE (0xffffffffef100004ULL) >> + >> static inline int vfio_mig_access(VFIODevice *vbasedev, void *val, int count, >> off_t off, bool iswrite) >> { >> @@ -166,6 +180,65 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask, >> return 0; >> } >> >> +/* ---------------------------------------------------------------------- */ >> + >> +static int vfio_save_setup(QEMUFile *f, void *opaque) >> +{ >> + VFIODevice *vbasedev = opaque; >> + VFIOMigration *migration = vbasedev->migration; >> + int ret; >> + >> + trace_vfio_save_setup(vbasedev->name); >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_SETUP_STATE); >> + >> + if (migration->region.mmaps) { >> + qemu_mutex_lock_iothread(); >> + ret = vfio_region_mmap(&migration->region); >> + qemu_mutex_unlock_iothread(); > > Please add a comment identifying why the iothread mutex lock is > necessary here. > >> + if (ret) { >> + error_report("%s: Failed to mmap VFIO migration region %d: %s", >> + vbasedev->name, migration->region.nr, > > We don't support multiple migration regions, is it useful to include > the region index here? > Ok. Removing region.nr >> + strerror(-ret)); >> + error_report("%s: Falling back to slow path", vbasedev->name); >> + } >> + } >> + >> + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_MASK, >> + VFIO_DEVICE_STATE_SAVING); >> + if (ret) { >> + error_report("%s: Failed to set state SAVING", vbasedev->name); >> + return ret; >> + } > > Again, doesn't match the function semantics that success only means the > device is in a non-error state, maybe the one that was asked for. > Fixed in patch 05. >> + >> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE); > > What's the overall purpose of writing these markers into the migration > stream? vfio_load_state() doesn't do anything with this other than > validate that the end-of-state immediately follows. Is this a > placeholder for something in the future? > Its not placeholder, it is used in vfio_load_state() to determine upto what point to loop to fetch data for each state, otherwise how would we know when to stop reading data from stream for that VFIO device. >> + >> + ret = qemu_file_get_error(f); >> + if (ret) { >> + return ret; >> + } >> + >> + return 0; >> +} >> + >> +static void vfio_save_cleanup(void *opaque) >> +{ >> + VFIODevice *vbasedev = opaque; >> + VFIOMigration *migration = vbasedev->migration; >> + >> + if (migration->region.mmaps) { >> + vfio_region_unmap(&migration->region); >> + } >> + trace_vfio_save_cleanup(vbasedev->name); >> +} >> + >> +static SaveVMHandlers savevm_vfio_handlers = { >> + .save_setup = vfio_save_setup, >> + .save_cleanup = vfio_save_cleanup, >> +}; >> + >> +/* ---------------------------------------------------------------------- */ >> + >> static void vfio_vmstate_change(void *opaque, int running, RunState state) >> { >> VFIODevice *vbasedev = opaque; >> @@ -225,6 +298,8 @@ static int vfio_migration_init(VFIODevice *vbasedev, >> struct vfio_region_info *info) >> { >> int ret = -EINVAL; >> + char id[256] = ""; >> + Object *obj; >> >> if (!vbasedev->ops->vfio_get_object) { >> return ret; >> @@ -241,6 +316,22 @@ static int vfio_migration_init(VFIODevice *vbasedev, >> return ret; >> } >> >> + obj = vbasedev->ops->vfio_get_object(vbasedev); >> + >> + if (obj) { >> + DeviceState *dev = DEVICE(obj); >> + char *oid = vmstate_if_get_id(VMSTATE_IF(dev)); >> + >> + if (oid) { >> + pstrcpy(id, sizeof(id), oid); >> + pstrcat(id, sizeof(id), "/"); >> + g_free(oid); >> + } >> + } > > Here's where vfio_migration_init() starts using vfio_get_object() as I > referenced back on patch 04. We might as well get the object before > calling vfio_migration_region_init() and then pass the object. The > conditional branch to handle obj is strange here too, it's fatal if > vfio_migration_region_init() doesn't find an object, why do we handle > it as optional here? Also, what is this doing? Comments would be > nice... Thanks, > Changing it as I mentioned in other patch reply. Thanks. > Alex > >> + pstrcat(id, sizeof(id), "vfio"); >> + >> + register_savevm_live(id, VMSTATE_INSTANCE_ID_ANY, 1, &savevm_vfio_handlers, >> + vbasedev); >> vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change, >> vbasedev); >> vbasedev->migration_state.notify = vfio_migration_state_notifier; >> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events >> index bcb3fa7314d7..982d8dccb219 100644 >> --- a/hw/vfio/trace-events >> +++ b/hw/vfio/trace-events >> @@ -152,3 +152,5 @@ vfio_migration_probe(const char *name, uint32_t index) " (%s) Region %d" >> vfio_migration_set_state(const char *name, uint32_t state) " (%s) state %d" >> vfio_vmstate_change(const char *name, int running, const char *reason, uint32_t dev_state) " (%s) running %d reason %s device state %d" >> vfio_migration_state_notifier(const char *name, const char *state) " (%s) state %s" >> +vfio_save_setup(const char *name) " (%s)" >> +vfio_save_cleanup(const char *name) " (%s)" >