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 6A8E6D2FEC0 for ; Tue, 27 Jan 2026 17:20:11 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vkmjN-0003sX-J7; Tue, 27 Jan 2026 12:20:00 -0500 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 1vkmiz-0003oM-2f for qemu-arm@nongnu.org; Tue, 27 Jan 2026 12:19:38 -0500 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 1vkmiw-0006Ub-Cn for qemu-arm@nongnu.org; Tue, 27 Jan 2026 12:19:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1769534369; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=j4FcsCOzt9Go6iDGSGzfYJgnVOU/yOn7qx1h1JsfNZw=; b=Y5yUwemKCcEu9CI/v1SVCFUUHTGgzX0a/ZGEQuAxvXGhG/bzXX8a+7Q2ixK+EzeK9Dpzkw WBCzqlG9cASVyvr6q9z/U+prqueToz0OfjRE9p27gh5VuwnHjD9+bgkwMh6HO07V9vlHyG u8oM0saZZwVE61acwrL1HujjA2+L07A= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-639-Q9x-8gf7NLqdeqsiJH7MsQ-1; Tue, 27 Jan 2026 12:19:25 -0500 X-MC-Unique: Q9x-8gf7NLqdeqsiJH7MsQ-1 X-Mimecast-MFC-AGG-ID: Q9x-8gf7NLqdeqsiJH7MsQ_1769534364 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1F38B19775A3; Tue, 27 Jan 2026 17:19:24 +0000 (UTC) Received: from localhost (pixel-6a.str.redhat.com [10.33.192.205]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B473D195419A; Tue, 27 Jan 2026 17:19:22 +0000 (UTC) From: Cornelia Huck To: Eric Auger , eric.auger.pro@gmail.com, eric.auger@redhat.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, peter.maydell@linaro.org, maz@kernel.org, oliver.upton@linux.dev, sebott@redhat.com, gshan@redhat.com, ddutile@redhat.com, peterx@redhat.com, philmd@linaro.org, pbonzini@redhat.com Subject: Re: [PATCH v6 08/11] hw/arm/virt: Declare AArch32 DBGDTRTX as safe to ignore in incoming stream In-Reply-To: <20260126165445.3033335-9-eric.auger@redhat.com> Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Avril Crosse O'Flaherty" References: <20260126165445.3033335-1-eric.auger@redhat.com> <20260126165445.3033335-9-eric.auger@redhat.com> User-Agent: Notmuch/0.39 (https://notmuchmail.org) Date: Tue, 27 Jan 2026 18:19:20 +0100 Message-ID: <87wm13rn1j.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=cohuck@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_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@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-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org Sender: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org On Mon, Jan 26 2026, Eric Auger wrote: > With the new infrastructure in place it is now feasible to teach > qemu that it is safe to ignore a sysreg in the incoming migration > stream. So with the plan to revert commit 4f2b82f60431 ("target/arm: > Reinstate bogus AArch32 DBGDTRTX register for migration compat") from > qemu 11.0 onwards, let's add a compat in 10.2 machine options stating > that this reg is safe to ignore. from 11.0 onwards we will not need > that register anymore. > > Signed-off-by: Eric Auger > > --- > > v4 -> v5: > - rebased on top of latest machine types (Connie) > > v3 -> v4: > - add a comment related to DBGDTRTX (Connie) > --- > hw/arm/virt.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/hw/arm/virt.c b/hw/arm/virt.c > index baa4e31aac1..03d5af18f26 100644 > --- a/hw/arm/virt.c > +++ b/hw/arm/virt.c > @@ -100,6 +100,15 @@ static GlobalProperty arm_virt_compat_defaults[] = { > static const size_t arm_virt_compat_defaults_len = > G_N_ELEMENTS(arm_virt_compat_defaults); > > +/* Register erronously exposed on 10.2 and earlier */ > +#define DBGDTRTX 0x40200000200e0298 > + > +static GlobalProperty arm_virt_compat_10_2[] = { > + { TYPE_ARM_CPU, "x-mig-safe-missing-regs", stringify(DBGDTRTX)}, > +}; > +static const size_t arm_virt_compat_10_2_len = > + G_N_ELEMENTS(arm_virt_compat_10_2); > + Not objecting, but we had a discussion recently regarding where compat values for arm cpus should live: https://lore.kernel.org/qemu-devel/20260120122108.131708-1-thuth@redhat.com/ ff. Could this become relevant for future other versioned machine types? I'd assume that they just would skip the bogus reg from the start, though. > /* > * This cannot be called from the virt_machine_class_init() because > * TYPE_VIRT_MACHINE is abstract and mc->compat_props g_ptr_array_new() > @@ -3552,6 +3561,7 @@ static void virt_machine_10_2_options(MachineClass *mc) > { > virt_machine_11_0_options(mc); > compat_props_add(mc->compat_props, hw_compat_10_2, hw_compat_10_2_len); > + compat_props_add(mc->compat_props, arm_virt_compat_10_2, arm_virt_compat_10_2_len); > } > DEFINE_VIRT_MACHINE(10, 2) >