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 DEF5BFD064E for ; Wed, 11 Mar 2026 07:43:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1w0EDI-0005sc-Hd; Wed, 11 Mar 2026 03:42:40 -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 1w0EDG-0005sE-OA; Wed, 11 Mar 2026 03:42:38 -0400 Received: from mgamail.intel.com ([192.198.163.8]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1w0EDE-00063u-Tq; Wed, 11 Mar 2026 03:42:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1773214956; x=1804750956; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=4VPH06at6S/BQIH/65F6vrzONUraudyS1Rej7YvhBlI=; b=cRQei0/ZUQvm+6HVFXQy7gNuRnoAJRGweeag9mlEh4mfNBf9fvLlNQAT 1l3V946TqmVpJ0tBB1vWJ6nHSAhPwmx5n7V82V/Py1sGMFxDZ4zrAxdbM uc4xb1pifgxSEyOE+ePGgfa6V7kzKqLo0DtWK99Ds7Ill58TfEdywmhA7 GWpjSrsFlL6+cZbneYhw4mVLQ8Ni70Yga98WPEWNOKM1YnNKDtB92YA6p IPo1XLyOYemy00txOPFU3n9DRcb1r5qzmw5aKn5KsQcqotEuQ8bQT4NRM 0GYF/vENZ/Tix7z9odjuBVF4FhLu7n0UlonXJE/lgr8ZA5vZ32EWvuzhh g==; X-CSE-ConnectionGUID: 7wjXyT0lTjiyZMyzTc0qLw== X-CSE-MsgGUID: WGRi4kHeQIGO1AsG7TQYvg== X-IronPort-AV: E=McAfee;i="6800,10657,11725"; a="91845148" X-IronPort-AV: E=Sophos;i="6.23,113,1770624000"; d="scan'208";a="91845148" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2026 00:42:32 -0700 X-CSE-ConnectionGUID: XK3k5crSR6u5uy1+aqMu7Q== X-CSE-MsgGUID: e8p/n7YIRUOmUs+84VCoEg== X-ExtLoop1: 1 Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.39]) by fmviesa003.fm.intel.com with ESMTP; 11 Mar 2026 00:42:30 -0700 Date: Wed, 11 Mar 2026 16:08:40 +0800 From: Zhao Liu To: Fiona Ebner Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org, mst@redhat.com, marcel.apfelbaum@gmail.com, pbonzini@redhat.com, richard.henderson@linaro.org, eduardo@habkost.net, peterx@redhat.com, farosas@suse.de, wangxinxin.wang@huawei.com Subject: Re: [PATCH v2] target/i386: add compat for migrating error code Message-ID: References: <20260310154348.495332-1-f.ebner@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260310154348.495332-1-f.ebner@proxmox.com> Received-SPF: pass client-ip=192.198.163.8; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 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_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.819, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.903, 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: qemu development 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 Tue, Mar 10, 2026 at 04:43:23PM +0100, Fiona Ebner wrote: > Date: Tue, 10 Mar 2026 16:43:23 +0100 > From: Fiona Ebner > Subject: [PATCH v2] target/i386: add compat for migrating error code > X-Mailer: git-send-email 2.47.3 > > If cpu->env.has_error_code is true, backwards migration of a VM from > a QEMU binary with commit 27535e9cca to a QEMU binary without commit > 27535e9cca will fail: > > > kvm: error while loading state for instance 0x0 of device 'cpu' > > In practice, wrongly setting the error code to 0 on the target is > often unproblematic, so additionally checking error_code != 0 in > cpu_errcode_needed() is not enough to mitigate the issue. Instead, add > proper machine version compat handling. > > Cc: qemu-stable@nongnu.org > Fixes: 27535e9cca ("target/i386: Add support for save/load of exception error code") > Signed-off-by: Fiona Ebner > --- > > Changes in v2: > * Add proper machine version compat rather than just checking if > error_code != 0. > > hw/i386/pc.c | 1 + > target/i386/cpu.c | 1 + > target/i386/cpu.h | 1 + > target/i386/machine.c | 2 +- > 4 files changed, 4 insertions(+), 1 deletion(-) ... > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index 5a62aa6157..ecae8593c8 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -2361,6 +2361,7 @@ struct ArchCPU { > bool expose_tcg; > bool migratable; > bool migrate_smi_count; only a nit, it's better to have a comment like: /* * Compatibility bits for old machine types. * If true, allow to migrate error code. */ > + bool migrate_error_code; > uint32_t apic_id; Reviewed-by: Zhao Liu