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(unknown [2a02:6bf:8080:b38::1:12]) by mail-nwsmtp-smtp-corp-main-56.klg.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id C1Ug0C0Fha60-cgescJDW; Tue, 23 Sep 2025 13:01:22 +0300 Precedence: bulk X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1758621682; bh=pBzg571zcaff+LTMRWyupFJ/ags+sUhQliNbfrNb9iQ=; h=Message-ID:Date:In-Reply-To:Cc:Subject:References:To:From; b=fgtkJ3jAaMjcf9kM+J3AYdXy3YbwKnSVS7WnxGrq/M8DE9o0QXEoJbjA6SBjj0GhA /Ak4epsjBYcG2t98q/8kk82gXjZLYG0FaLjEJhOZCvhSH4o+PlFH9aFGJXazucjksU m4iLMVNeulTqjqyRAcEU2NM+PRuT+QxNLYxuFBT0= Authentication-Results: mail-nwsmtp-smtp-corp-main-56.klg.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: mst@redhat.com Cc: qemu-devel@nongnu.org, philmd@linaro.org, thuth@redhat.com, eblake@redhat.com, michael.roth@amd.com, armbru@redhat.com, farosas@suse.de, peterx@redhat.com, berrange@redhat.com, jasowang@redhat.com, steven.sistare@oracle.com, leiyang@redhat.com, davydov-max@yandex-team.ru, yc-core@yandex-team.ru, vsementsov@yandex-team.ru Subject: [PATCH v6 16/19] qapi: add interface for backend-transfer virtio-net/tap migration Date: Tue, 23 Sep 2025 13:01:07 +0300 Message-ID: <20250923100110.70862-17-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250923100110.70862-1-vsementsov@yandex-team.ru> References: <20250923100110.70862-1-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=2a02:6b8:c41:1300:1:45:d181:df01; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1d.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, T_SPF_HELO_TEMPERROR=0.01, T_SPF_TEMPERROR=0.01 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: 1758621822317116600 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. Signed-off-by: Vladimir Sementsov-Ogievskiy --- include/qapi/util.h | 17 ++++++++++++++++ migration/options.c | 32 ++++++++++++++++++++++++++++++ migration/options.h | 2 ++ qapi/migration.json | 47 ++++++++++++++++++++++++++++++++++++--------- 4 files changed, 89 insertions(+), 9 deletions(-) diff --git a/include/qapi/util.h b/include/qapi/util.h index 29bc4eb865..b953402416 100644 --- a/include/qapi/util.h +++ b/include/qapi/util.h @@ -69,4 +69,21 @@ int parse_qapi_name(const char *name, bool complete); _len; \ }) =20 +/* + * For any GenericList @list, return true if it contains specified + * element. + */ +#define QAPI_LIST_CONTAINS(list, el) \ + ({ \ + bool _found =3D false; \ + typeof_strip_qual(list) _tail; \ + for (_tail =3D list; _tail !=3D NULL; _tail =3D _tail->next) { \ + if (_tail->value =3D=3D el) { \ + _found =3D true; \ + break; \ + } \ + } \ + _found; \ + }) + #endif diff --git a/migration/options.c b/migration/options.c index 4e923a2e07..137ca2147e 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 +263,14 @@ 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(); + + return QAPI_LIST_CONTAINS(s->parameters.backend_transfer, + BACKEND_TRANSFER_VIRTIO_NET_TAP); +} + bool migrate_ignore_shared(void) { MigrationState *s =3D migrate_get_current(); @@ -960,6 +969,12 @@ MigrationParameters *qmp_query_migrate_parameters(Erro= r **errp) params->has_direct_io =3D true; params->direct_io =3D s->parameters.direct_io; =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 @@ -993,6 +1008,7 @@ void migrate_params_init(MigrationParameters *params) params->has_mode =3D true; params->has_zero_page_detection =3D true; params->has_direct_io =3D true; + params->has_backend_transfer =3D true; } =20 /* @@ -1179,6 +1195,11 @@ bool migrate_params_check(MigrationParameters *param= s, Error **errp) return false; } =20 + if (params->has_backend_transfer) { + error_setg(errp, "Not implemented"); + return false; + } + return true; } =20 @@ -1297,6 +1318,10 @@ static void migrate_params_test_apply(MigrateSetPara= meters *params, if (params->has_direct_io) { dest->direct_io =3D params->direct_io; } + + if (params->has_backend_transfer) { + dest->backend_transfer =3D params->backend_transfer; + } } =20 static void migrate_params_apply(MigrateSetParameters *params, Error **err= p) @@ -1429,6 +1454,13 @@ static void migrate_params_apply(MigrateSetParameter= s *params, Error **errp) if (params->has_direct_io) { s->parameters.direct_io =3D params->direct_io; } + + 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 2387c21e9c..e39785dc07 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -747,6 +747,18 @@ '*transform': 'BitmapMigrationBitmapAliasTransform' } } =20 +## +# @BackendTransfer: +# +# @virtio-net-tap: Enable backend-transfer migration for virtio-net/tap. W= hen +# enabled, TAP fds and all related state is passed to target QEMU thro= ugh +# migration channel (which should be unix socket). +# +# Since: 10.2 +## +{ 'enum': 'BackendTransfer', + 'data': [ 'virtio-net-tap' ] } + ## # @BitmapMigrationNodeAlias: # @@ -924,10 +936,14 @@ # only has effect if the @mapped-ram capability is enabled. # (Since 9.1) # +# @backend-transfer: List of targets to enable backend-transfer +# migration for. This requires migration channel to be a unix +# socket (to pass fds through). (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and -# @x-vcpu-dirty-limit-period are experimental. +# @unstable: Members @x-checkpoint-delay, +# @x-vcpu-dirty-limit-period and @backend-transfer are experimental. # # Since: 2.4 ## @@ -950,7 +966,8 @@ 'vcpu-dirty-limit', 'mode', 'zero-page-detection', - 'direct-io'] } + 'direct-io', + 'backend-transfer' ] } =20 ## # @MigrateSetParameters: @@ -1105,10 +1122,14 @@ # only has effect if the @mapped-ram capability is enabled. # (Since 9.1) # +# @backend-transfer: List of targets to enable backend-transfer +# migration for. This requires migration channel to be a unix +# socket (to pass fds through). (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and -# @x-vcpu-dirty-limit-period are experimental. +# @unstable: Members @x-checkpoint-delay, +# @x-vcpu-dirty-limit-period and @backend-transfer are experimental. # # TODO: either fuse back into `MigrationParameters`, or make # `MigrationParameters` members mandatory @@ -1146,7 +1167,9 @@ '*vcpu-dirty-limit': 'uint64', '*mode': 'MigMode', '*zero-page-detection': 'ZeroPageDetection', - '*direct-io': 'bool' } } + '*direct-io': 'bool', + '*backend-transfer': { 'type': [ 'BackendTransfer' ], + 'features': [ 'unstable' ] } } } =20 ## # @migrate-set-parameters: @@ -1315,10 +1338,14 @@ # only has effect if the @mapped-ram capability is enabled. # (Since 9.1) # +# @backend-transfer: List of targets to enable backend-transfer +# migration for. This requires migration channel to be a unix +# socket (to pass fds through). (Since 10.2) +# # Features: # -# @unstable: Members @x-checkpoint-delay and -# @x-vcpu-dirty-limit-period are experimental. +# @unstable: Members @x-checkpoint-delay, +# @x-vcpu-dirty-limit-period and @backend-transfer are experimental. # # Since: 2.4 ## @@ -1353,7 +1380,9 @@ '*vcpu-dirty-limit': 'uint64', '*mode': 'MigMode', '*zero-page-detection': 'ZeroPageDetection', - '*direct-io': 'bool' } } + '*direct-io': 'bool', + '*backend-transfer': { 'type': [ 'BackendTransfer' ], + 'features': [ 'unstable' ] } } } =20 ## # @query-migrate-parameters: --=20 2.48.1