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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1751618764; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QCmQhzgK8imggIgqcbYivoAqw0X5+C7YbCCtSUdop2w=; b=Y4YERoVChFd7Te7jQax4U7/s2we2oYcI7lP9HtJD4hQAoC00Lcv0wGeRMP0Or0LLAxli6G 2oSL7qT2FwKcOtPOHbA3AizHmofVF3afFx7sOhOYTXocaH6BCP4ZGz/nyEx0fcZ9loUxMi Vjvn+E29J6QmJOe3pip5QvSG59lb7kc= X-MC-Unique: W9q-DJeUP3uIcqk2AnJuXQ-1 X-Mimecast-MFC-AGG-ID: W9q-DJeUP3uIcqk2AnJuXQ_1751618760 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= To: qemu-devel@nongnu.org Cc: Alex Williamson , Steve Sistare , Fabiano Rosas , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [PULL 10/27] migration: cpr_get_fd_param helper Date: Fri, 4 Jul 2025 10:45:11 +0200 Message-ID: <20250704084528.1412959-11-clg@redhat.com> In-Reply-To: <20250704084528.1412959-1-clg@redhat.com> References: <20250704084528.1412959-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 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=170.10.133.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.237, 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 Precedence: list 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 @redhat.com) X-ZM-MESSAGEID: 1751618887657116600 From: Steve Sistare Add the helper function cpr_get_fd_param, to use when preserving a file descriptor that is opened externally and passed to QEMU. cpr_get_fd_param returns a descriptor number either from a QEMU command-line parameter, from a getfd command, or from CPR state. When a descriptor is passed to new QEMU via SCM_RIGHTS, its number changes. Hence, during CPR, the command-line parameter is ignored in new QEMU, and over-ridden by the value found in CPR state. Similarly, if the descriptor was originally specified by a getfd command in old QEMU, the fd number is not known outside of QEMU, and it changes when sent to new QEMU via SCM_RIGHTS. Hence the user cannot send getfd to new QEMU, but when the user sends a hotplug command that references the fd, cpr_get_fd_param finds its value in CPR state. Signed-off-by: Steve Sistare Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/qemu-devel/1751493538-202042-5-git-send-email= -steven.sistare@oracle.com Signed-off-by: C=C3=A9dric Le Goater --- include/migration/cpr.h | 2 ++ migration/cpr.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+) diff --git a/include/migration/cpr.h b/include/migration/cpr.h index 07858e93fa2fbd9ca0c31af218216025c14369a6..eb27a933017a09c480029a50cd6= b1457e69cec8a 100644 --- a/include/migration/cpr.h +++ b/include/migration/cpr.h @@ -32,6 +32,8 @@ void cpr_state_close(void); struct QIOChannel *cpr_state_ioc(void); =20 bool cpr_incoming_needed(void *opaque); +int cpr_get_fd_param(const char *name, const char *fdname, int index, + Error **errp); =20 QEMUFile *cpr_transfer_output(MigrationChannel *channel, Error **errp); QEMUFile *cpr_transfer_input(MigrationChannel *channel, Error **errp); diff --git a/migration/cpr.c b/migration/cpr.c index a50a57edca754b50e68fa9c294b3c89791e62ba8..535d587aee16d2411d20ee549f8= e3cf5a4120a88 100644 --- a/migration/cpr.c +++ b/migration/cpr.c @@ -13,6 +13,7 @@ #include "migration/qemu-file.h" #include "migration/savevm.h" #include "migration/vmstate.h" +#include "monitor/monitor.h" #include "system/runstate.h" #include "trace.h" =20 @@ -264,3 +265,39 @@ bool cpr_incoming_needed(void *opaque) MigMode mode =3D migrate_mode(); return mode =3D=3D MIG_MODE_CPR_TRANSFER; } + +/* + * cpr_get_fd_param: find a descriptor and return its value. + * + * @name: CPR name for the descriptor + * @fdname: An integer-valued string, or a name passed to a getfd command + * @index: CPR index of the descriptor + * @errp: returned error message + * + * If CPR is not being performed, then use @fdname to find the fd. + * If CPR is being performed, then ignore @fdname, and look for @name + * and @index in CPR state. + * + * On success returns the fd value, else returns -1. + */ +int cpr_get_fd_param(const char *name, const char *fdname, int index, + Error **errp) +{ + ERRP_GUARD(); + int fd; + + if (cpr_is_incoming()) { + fd =3D cpr_find_fd(name, index); + if (fd < 0) { + error_setg(errp, "cannot find saved value for fd %s", fdname); + } + } else { + fd =3D monitor_fd_param(monitor_cur(), fdname, errp); + if (fd >=3D 0) { + cpr_save_fd(name, index, fd); + } else { + error_prepend(errp, "Could not parse object fd %s:", fdname); + } + } + return fd; +} --=20 2.50.0