From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57897) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkbJZ-0005dM-Hj for qemu-devel@nongnu.org; Wed, 14 May 2014 11:42:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WkbJR-0006wE-9Q for qemu-devel@nongnu.org; Wed, 14 May 2014 11:41:53 -0400 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:55119) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkbJQ-0006w8-WB for qemu-devel@nongnu.org; Wed, 14 May 2014 11:41:45 -0400 Received: from /spool/local by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 14 May 2014 16:41:44 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 8592D1B08041 for ; Wed, 14 May 2014 16:41:55 +0100 (BST) Received: from d06av07.portsmouth.uk.ibm.com (d06av07.portsmouth.uk.ibm.com [9.149.37.248]) by b06cxnps4076.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s4EFfeum065968 for ; Wed, 14 May 2014 15:41:40 GMT Received: from d06av07.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av07.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s4EFfeTB006834 for ; Wed, 14 May 2014 11:41:40 -0400 From: Greg Kurz Date: Wed, 14 May 2014 17:41:38 +0200 Message-ID: <20140514154137.10746.94708.stgit@bahia.local> In-Reply-To: <20140514154130.10746.1412.stgit@bahia.local> References: <20140514154130.10746.1412.stgit@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH RFC 1/8] virtio: add subsections to the migration stream List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , Anthony Liguori , "Michael S. Tsirkin" , Stefan Hajnoczi , Amit Shah , Paolo Bonzini Cc: Juan Quintela , Fam Zheng , Alexander Graf , Andreas =?utf-8?q?F=C3=A4rber?= , qemu-devel@nongnu.org There is a need to add some more fields to VirtIODevice that should be migrated (broken status, endianness). The problem is that we do not want to break compatibility while adding a new feature... This issue has been addressed in the generic VMState code with the use of optional subsections. As a *temporary* alternative to port the whole virtio migration code to VMState, this patch mimics a similar subsectionning ability for virtio. Since each virtio device is streamed in its own section, the idea is to stream subsections between the end of the device section and the start of the next sections. This allows an older QEMU to complain and exit when fed with subsections: Unknown savevm section type 5 Error -22 while loading VM state All users of virtio_load()/virtio_save() need to be patched because the subsections are streamed AFTER the device itself. Suggested-by: Alexander Graf Signed-off-by: Greg Kurz --- hw/virtio/virtio.c | 65 ++++++++++++++++++++++++++++++++++++++++++++ include/hw/virtio/virtio.h | 4 +++ 2 files changed, 69 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index aeabf3a..f4eaa3f 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -19,6 +19,7 @@ #include "hw/virtio/virtio.h" #include "qemu/atomic.h" #include "hw/virtio/virtio-bus.h" +#include "migration/migration.h" /* * The alignment to use between consumer and producer parts of vring. @@ -833,6 +834,70 @@ void virtio_notify_config(VirtIODevice *vdev) virtio_notify_vector(vdev, vdev->config_vector); } +static const struct VirtIOSubsectionDescStruct { + const char *name; + int version_id; + void (*save)(VirtIODevice *vdev, QEMUFile *f); + int (*load)(VirtIODevice *vdev, QEMUFile *f); +} virtio_subsection[] = { + { .name = NULL } +}; + +void virtio_save_subsections(VirtIODevice *vdev, QEMUFile *f) +{ + int i; + + for (i = 0; virtio_subsection[i].name; i++) { + const char *name = virtio_subsection[i].name; + uint8_t len = strlen(name); + + qemu_put_byte(f, QEMU_VM_SUBSECTION); + qemu_put_byte(f, len); + qemu_put_buffer(f, (uint8_t *) name, len); + qemu_put_be32(f, virtio_subsection[i].version_id); + (*virtio_subsection[i].save)(vdev, f); + } +} + +int virtio_load_subsections(VirtIODevice *vdev, QEMUFile *f) +{ + while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) { + char idstr[256]; + uint8_t len, size; + int i; + + len = qemu_peek_byte(f, 1); + size = qemu_peek_buffer(f, (uint8_t *) idstr, len, 2); + if (size != len) { + break; + } + + idstr[size] = 0; + + for (i = 0; virtio_subsection[i].name; i++) { + if (strcmp(virtio_subsection[i].name, idstr) == 0) { + uint32_t version_id; + int ret; + + qemu_file_skip(f, 1); /* subsection */ + qemu_file_skip(f, 1); /* len */ + qemu_file_skip(f, len); /* idstr */ + + version_id = qemu_get_be32(f); + if (version_id > virtio_subsection[i].version_id) { + return -EINVAL; + } + ret = (*virtio_subsection[i].load)(vdev, f); + if (ret) { + return ret; + } + } + } + } + + return 0; +} + void virtio_save(VirtIODevice *vdev, QEMUFile *f) { BusState *qbus = qdev_get_parent_bus(DEVICE(vdev)); diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 3e54e90..82f852f 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -186,6 +186,10 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f); int virtio_load(VirtIODevice *vdev, QEMUFile *f); +void virtio_save_subsections(VirtIODevice *vdev, QEMUFile *f); + +int virtio_load_subsections(VirtIODevice *vdev, QEMUFile *f); + void virtio_notify_config(VirtIODevice *vdev); void virtio_queue_set_notification(VirtQueue *vq, int enable);