From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] target-i386: fix losing XCR0 processor state component bits Date: Wed, 28 Sep 2016 17:01:01 +0200 Message-ID: <67000e1f-e521-e293-6d61-80f1c41976dc@gnu.org> References: <1475040669-29085-1-git-send-email-wanpeng.li@hotmail.com> <20160928145737.GJ3877@thinpad.lan.raisama.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Wanpeng Li , kvm@vger.kernel.org, qemu-devel@nongnu.org, Wanpeng Li , Richard Henderson , "Michael S. Tsirkin" To: Eduardo Habkost Return-path: Received: from mail-wm0-f54.google.com ([74.125.82.54]:38318 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932794AbcI1PBE (ORCPT ); Wed, 28 Sep 2016 11:01:04 -0400 Received: by mail-wm0-f54.google.com with SMTP id l132so75896180wmf.1 for ; Wed, 28 Sep 2016 08:01:04 -0700 (PDT) In-Reply-To: <20160928145737.GJ3877@thinpad.lan.raisama.net> Sender: kvm-owner@vger.kernel.org List-ID: On 28/09/2016 16:57, Eduardo Habkost wrote:\ > This can be fixed by adding actual property names to the > FEAT_XSAVE_COMP_* bits. This way we will be able to report > meaningful names to management in case GET_SUPPORTED_CPUID says a > given xsave component is not supported yet, and will ensure we > correctly treat still-unknown xsave components as unmigratable. Hmm, right. Even though XSAVE could be migrated as a blob, QEMU marshals and unmarshals the registers out and back into the xsave data, so that unknown features are indeed unmigratable. But are the property names necessary? It makes no sense to enable/disable XSAVE components separately from the other CPUID bits that enable them. Could we just mark all unknown features as unmigratable without giving them names? Paolo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43628) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpGM8-0000xK-J1 for qemu-devel@nongnu.org; Wed, 28 Sep 2016 11:01:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpGM4-0007Sy-Ch for qemu-devel@nongnu.org; Wed, 28 Sep 2016 11:01:07 -0400 Received: from mail-wm0-x230.google.com ([2a00:1450:400c:c09::230]:37213) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpGM4-0007Ss-6B for qemu-devel@nongnu.org; Wed, 28 Sep 2016 11:01:04 -0400 Received: by mail-wm0-x230.google.com with SMTP id b130so76194910wmc.0 for ; Wed, 28 Sep 2016 08:01:03 -0700 (PDT) Sender: Paolo Bonzini References: <1475040669-29085-1-git-send-email-wanpeng.li@hotmail.com> <20160928145737.GJ3877@thinpad.lan.raisama.net> From: Paolo Bonzini Message-ID: <67000e1f-e521-e293-6d61-80f1c41976dc@gnu.org> Date: Wed, 28 Sep 2016 17:01:01 +0200 MIME-Version: 1.0 In-Reply-To: <20160928145737.GJ3877@thinpad.lan.raisama.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] target-i386: fix losing XCR0 processor state component bits List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Wanpeng Li , kvm@vger.kernel.org, qemu-devel@nongnu.org, Wanpeng Li , Richard Henderson , "Michael S. Tsirkin" On 28/09/2016 16:57, Eduardo Habkost wrote:\ > This can be fixed by adding actual property names to the > FEAT_XSAVE_COMP_* bits. This way we will be able to report > meaningful names to management in case GET_SUPPORTED_CPUID says a > given xsave component is not supported yet, and will ensure we > correctly treat still-unknown xsave components as unmigratable. Hmm, right. Even though XSAVE could be migrated as a blob, QEMU marshals and unmarshals the registers out and back into the xsave data, so that unknown features are indeed unmigratable. But are the property names necessary? It makes no sense to enable/disable XSAVE components separately from the other CPUID bits that enable them. Could we just mark all unknown features as unmigratable without giving them names? Paolo