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(unknown [2a02:6bf:8080:a89::1:23]) by mail-nwsmtp-smtp-corp-main-80.iva.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id xdPFQ30FtmI0-7AA8UpLt; Fri, 10 Oct 2025 20:40:15 +0300 Precedence: bulk X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1760118015; bh=4QZahEI9jXh4SY0arLFmkWwqBvNmEl03FiavUfOzMw4=; h=Message-ID:Date:In-Reply-To:Cc:Subject:References:To:From; b=P79CGupdtdmTnEvoM7CQzh6iNbipS2j1A1KGRVPfX97PQf/OvuR+Llf7wFLDfaw1L LZkXx171rLL36NuijXBEN7z16HBQaRkkgqNUcixXJLfVzuP5fgLmtlJkRIV5QrhLWb wW5+bNFaxsFwxbwcqmdtViTVMpCVhqashE6p+mJQ= Authentication-Results: mail-nwsmtp-smtp-corp-main-80.iva.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: mst@redhat.com, jasowang@redhat.com Cc: peterx@redhat.com, farosas@suse.de, sw@weilnetz.de, eblake@redhat.com, armbru@redhat.com, thuth@redhat.com, philmd@linaro.org, berrange@redhat.com, qemu-devel@nongnu.org, michael.roth@amd.com, steven.sistare@oracle.com, leiyang@redhat.com, davydov-max@yandex-team.ru, yc-core@yandex-team.ru, vsementsov@yandex-team.ru, raphael.s.norwitz@gmail.com Subject: [PATCH v7 16/19] qapi: add interface for backend-transfer virtio-net/tap migration Date: Fri, 10 Oct 2025 20:39:54 +0300 Message-ID: <20251010173957.166759-17-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251010173957.166759-1-vsementsov@yandex-team.ru> References: <20251010173957.166759-1-vsementsov@yandex-team.ru> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=178.154.239.72; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1a.mail.yandex.net X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, 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: 2.1.29 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @yandex-team.ru) X-ZM-MESSAGEID: 1760118326228158500 Content-Type: text/plain; charset="utf-8" To migrate virtio-net TAP device backend (including open fds) locally, user should simply set migration parameter backend-transfer =3D ["virtio-net-tap"] Why not simple boolean? To simplify migration to further versions, when more devices will support backend-transfer migration. Alternatively, we may add per-device option to disable backend-transfer migration, but still: 1. It's more comfortable to set same capabilities/parameters on both source and target QEMU, than care about each device. 2. To not break the design, that machine-type + device options + migration capabilities and parameters are fully define the resulting migration stream. We'll break this if add in future more backend-transfer support in devices under same backend-transfer=3Dtrue parameter. The commit only brings the interface, the realization will come in later commit. That's why we add a temporary not-implemented error in migrate_params_check(). Signed-off-by: Vladimir Sementsov-Ogievskiy --- migration/options.c | 39 +++++++++++++++++++++++++++++++++++++++ migration/options.h | 2 ++ qapi/migration.json | 42 ++++++++++++++++++++++++++++++++++++------ 3 files changed, 77 insertions(+), 6 deletions(-) diff --git a/migration/options.c b/migration/options.c index 5183112775..76709af3ab 100644 --- a/migration/options.c +++ b/migration/options.c @@ -13,6 +13,7 @@ =20 #include "qemu/osdep.h" #include "qemu/error-report.h" +#include "qapi/util.h" #include "exec/target_page.h" #include "qapi/clone-visitor.h" #include "qapi/error.h" @@ -262,6 +263,20 @@ bool migrate_mapped_ram(void) return s->capabilities[MIGRATION_CAPABILITY_MAPPED_RAM]; } =20 +bool migrate_virtio_net_tap(void) +{ + MigrationState *s =3D migrate_get_current(); + BackendTransferList *el =3D s->parameters.backend_transfer; + + for ( ; el; el =3D el->next) { + if (el->value =3D=3D BACKEND_TRANSFER_VIRTIO_NET_TAP) { + return true; + } + } + + return false; +} + bool migrate_ignore_shared(void) { MigrationState *s =3D migrate_get_current(); @@ -963,6 +978,12 @@ MigrationParameters *qmp_query_migrate_parameters(Erro= r **errp) params->cpr_exec_command =3D QAPI_CLONE(strList, s->parameters.cpr_exec_command); =20 + if (s->parameters.backend_transfer) { + params->has_backend_transfer =3D true; + params->backend_transfer =3D QAPI_CLONE(BackendTransferList, + s->parameters.backend_transf= er); + } + return params; } =20 @@ -997,6 +1018,7 @@ void migrate_params_init(MigrationParameters *params) params->has_zero_page_detection =3D true; params->has_direct_io =3D true; params->has_cpr_exec_command =3D true; + params->has_backend_transfer =3D true; } =20 /* @@ -1183,6 +1205,12 @@ bool migrate_params_check(MigrationParameters *param= s, Error **errp) return false; } =20 + /* TODO: implement backend-transfer and remove this check */ + if (params->has_backend_transfer) { + error_setg(errp, "Not implemented"); + return false; + } + return true; } =20 @@ -1305,6 +1333,10 @@ static void migrate_params_test_apply(MigrateSetPara= meters *params, if (params->has_cpr_exec_command) { dest->cpr_exec_command =3D params->cpr_exec_command; } + + if (params->has_backend_transfer) { + dest->backend_transfer =3D params->backend_transfer; + } } =20 static void migrate_params_apply(MigrateSetParameters *params, Error **err= p) @@ -1443,6 +1475,13 @@ static void migrate_params_apply(MigrateSetParameter= s *params, Error **errp) s->parameters.cpr_exec_command =3D QAPI_CLONE(strList, params->cpr_exec_command); } + + if (params->has_backend_transfer) { + qapi_free_BackendTransferList(s->parameters.backend_transfer); + + s->parameters.backend_transfer =3D QAPI_CLONE(BackendTransferList, + params->backend_transf= er); + } } =20 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp) diff --git a/migration/options.h b/migration/options.h index 82d839709e..55c0345433 100644 --- a/migration/options.h +++ b/migration/options.h @@ -87,6 +87,8 @@ const char *migrate_tls_hostname(void); uint64_t migrate_xbzrle_cache_size(void); ZeroPageDetection migrate_zero_page_detection(void); =20 +bool migrate_virtio_net_tap(void); + /* parameters helpers */ =20 bool migrate_params_check(MigrationParameters *params, Error **errp); diff --git a/qapi/migration.json b/qapi/migration.json index be0f3fcc12..1bfe7df191 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -770,6 +770,19 @@ '*transform': 'BitmapMigrationBitmapAliasTransform' } } =20 +## +# @BackendTransfer: +# +# @virtio-net-tap: Enable backend-transfer migration for +# virtio-net/tap. When enabled, TAP fds and all related state are +# passed to the destination in the migration channel (which must +# be a UNIX domain socket). +# +# Since: 10.2 +## +{ 'enum': 'BackendTransfer', + 'data': [ 'virtio-net-tap' ] } + ## # @BitmapMigrationNodeAlias: # @@ -951,9 +964,13 @@ # is @cpr-exec. The first list element is the program's filename, # the remainder its arguments. (Since 10.2) # +# @backend-transfer: List of targets for backend-transfer migration. +# See description in `BackendTransfer`. Default is no +# backend-transfer migration (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and +# @unstable: Members @backend-transfer, @x-checkpoint-delay and # @x-vcpu-dirty-limit-period are experimental. # # Since: 2.4 @@ -978,7 +995,8 @@ 'mode', 'zero-page-detection', 'direct-io', - 'cpr-exec-command'] } + 'cpr-exec-command', + { 'name': 'backend-transfer', 'features': ['unstable'] } ] } =20 ## # @MigrateSetParameters: @@ -1137,9 +1155,13 @@ # is @cpr-exec. The first list element is the program's filename, # the remainder its arguments. (Since 10.2) # +# @backend-transfer: List of targets for backend-transfer migration. +# See description in `BackendTransfer`. Default is no +# backend-transfer migration (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and +# @unstable: Members @backend-transfer, @x-checkpoint-delay and # @x-vcpu-dirty-limit-period are experimental. # # TODO: either fuse back into `MigrationParameters`, or make @@ -1179,7 +1201,9 @@ '*mode': 'MigMode', '*zero-page-detection': 'ZeroPageDetection', '*direct-io': 'bool', - '*cpr-exec-command': [ 'str' ]} } + '*cpr-exec-command': [ 'str' ], + '*backend-transfer': { 'type': [ 'BackendTransfer' ], + 'features': [ 'unstable' ] } } } =20 ## # @migrate-set-parameters: @@ -1352,9 +1376,13 @@ # is @cpr-exec. The first list element is the program's filename, # the remainder its arguments. (Since 10.2) # +# @backend-transfer: List of targets for backend-transfer migration. +# See description in `BackendTransfer`. Default is no +# backend-transfer migration (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and +# @unstable: Members @backend-transfer, @x-checkpoint-delay and # @x-vcpu-dirty-limit-period are experimental. # # Since: 2.4 @@ -1391,7 +1419,9 @@ '*mode': 'MigMode', '*zero-page-detection': 'ZeroPageDetection', '*direct-io': 'bool', - '*cpr-exec-command': [ 'str' ]} } + '*cpr-exec-command': [ 'str' ], + '*backend-transfer': { 'type': [ 'BackendTransfer' ], + 'features': [ 'unstable' ] } } } =20 ## # @query-migrate-parameters: --=20 2.48.1