From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 28CCAE784B8 for ; Mon, 2 Oct 2023 14:35:04 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qnK0H-0001yP-CK; Mon, 02 Oct 2023 10:34:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qnK0G-0001yF-BA for qemu-devel@nongnu.org; Mon, 02 Oct 2023 10:34:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qnK0E-0008FM-Jh for qemu-devel@nongnu.org; Mon, 02 Oct 2023 10:34:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1696257269; 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=NE3A6OQMBRJL0RtCX9BdC3ztW/Y64RZCzoFi34WUS6U=; b=PEHP2ffRucT9Jp2LR0GqjEjSieR6QBCjTw9wUEXmC34HP7UyFQIj/Uk7+hcTqWoDBLFZEa sYD6Lq3AXOpqz6MM8GP66fxF13T5x9CBk56sAreaspBc95lj2IUEuPH+Zr+vIxU5EsQnlA zqkcj2iHMRAZl6hF2CKZUXE+78I8OZk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-683-wScd3lVYNLe3qmq0ODC6CA-1; Mon, 02 Oct 2023 10:34:27 -0400 X-MC-Unique: wScd3lVYNLe3qmq0ODC6CA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6F82297E403 for ; Mon, 2 Oct 2023 14:34:27 +0000 (UTC) Received: from [10.39.194.43] (unknown [10.39.194.43]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D0ED49A; Mon, 2 Oct 2023 14:34:26 +0000 (UTC) Message-ID: <9786677d-9451-63c1-2804-26f4474d45d9@redhat.com> Date: Mon, 2 Oct 2023 16:34:25 +0200 MIME-Version: 1.0 Subject: Re: [PATCH v2 3/5] ramfb: implement migration support Content-Language: en-US To: marcandre.lureau@redhat.com, qemu-devel@nongnu.org Cc: kraxel@redhat.com References: <20231002111154.1002655-1-marcandre.lureau@redhat.com> <20231002111154.1002655-4-marcandre.lureau@redhat.com> From: Laszlo Ersek In-Reply-To: <20231002111154.1002655-4-marcandre.lureau@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=lersek@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, 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_H4=0.001, RCVD_IN_MSPIKE_WL=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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 10/2/23 13:11, marcandre.lureau@redhat.com wrote: > From: Marc-André Lureau > > Implementing RAMFB migration is quite straightforward. One caveat is to > treat the whole RAMFBCfg as a blob, since that's what is exposed to the > guest directly. This avoid having to fiddle with endianness issues if we > were to migrate fields individually as integers. > > The following patches turns the migration only on machine >= 8.2. > > Fixes: > https://bugzilla.redhat.com/show_bug.cgi?id=1859424 > > Signed-off-by: Marc-André Lureau > --- > hw/display/ramfb.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c > index 79b9754a58..4aaaa7d653 100644 > --- a/hw/display/ramfb.c > +++ b/hw/display/ramfb.c > @@ -12,6 +12,7 @@ > */ > > #include "qemu/osdep.h" > +#include "migration/vmstate.h" > #include "qapi/error.h" > #include "hw/loader.h" > #include "hw/display/ramfb.h" > @@ -28,6 +29,8 @@ struct QEMU_PACKED RAMFBCfg { > uint32_t stride; > }; > > +typedef struct RAMFBCfg RAMFBCfg; > + > struct RAMFBState { > DisplaySurface *ds; > uint32_t width, height; > @@ -115,6 +118,23 @@ void ramfb_display_update(QemuConsole *con, RAMFBState *s) > dpy_gfx_update_full(con); > } > > +static int ramfb_post_load(void *opaque, int version_id) > +{ > + ramfb_fw_cfg_write(opaque, 0, 0); > + return 0; > +} > + > +static const VMStateDescription vmstate_ramfb = { > + .name = "ramfb", > + .version_id = 1, > + .minimum_version_id = 1, > + .post_load = ramfb_post_load, > + .fields = (VMStateField[]) { > + VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)), I just couldn't figure out, from code review, why VMSTATE_BUFFER would not work here. So I applied your patches, changed this like follows: diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c index 077fd2fa2c31..04bf01059994 100644 --- a/hw/display/ramfb.c +++ b/hw/display/ramfb.c @@ -131,7 +131,7 @@ static const VMStateDescription vmstate_ramfb = { .minimum_version_id = 1, .post_load = ramfb_post_load, .fields = (VMStateField[]) { - VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)), + VMSTATE_BUFFER(cfg, RAMFBState), VMSTATE_END_OF_LIST() } }; and tried to build it. I got a wall of error messages about cryptic macro nesting. I'm quite annoyed that nearly none of the VMSTATE_ macros are documented; even git-blame tends to be unhelpful. Ultimately though, there was one useful bit in the wall of error messages: the error was related to "type_check_array". Upon reviewing type_check_array, my impression is that VMSTATE_BUFFER is suitable only for *array fields*. I randomly picked an existent example, namely static const VMStateDescription bulk_in_vmstate = { .name = "CCID BulkIn state", .version_id = 1, .minimum_version_id = 1, .fields = (VMStateField[]) { VMSTATE_BUFFER(data, BulkIn), VMSTATE_UINT32(len, BulkIn), VMSTATE_UINT32(pos, BulkIn), VMSTATE_END_OF_LIST() } }; from "hw/usb/dev-smartcard-reader.c", and sure enough, "data" is an array field in BulkIn: typedef struct BulkIn { uint8_t data[BULK_IN_BUF_SIZE]; uint32_t len; uint32_t pos; } BulkIn; So that's the reason. Again, annoying lack of documentation, but I agree that your VMSTATE_BUFFER_UNSAFE application is judicious. Thanks! Laszlo > + VMSTATE_END_OF_LIST() > + } > +}; > + > RAMFBState *ramfb_setup(Error **errp) > { > FWCfgState *fw_cfg = fw_cfg_find(); > @@ -127,6 +147,7 @@ RAMFBState *ramfb_setup(Error **errp) > > s = g_new0(RAMFBState, 1); > > + vmstate_register(NULL, 0, &vmstate_ramfb, s); > rom_add_vga("vgabios-ramfb.bin"); > fw_cfg_add_file_callback(fw_cfg, "etc/ramfb", > NULL, ramfb_fw_cfg_write, s,