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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B662CC04E69 for ; Mon, 14 Aug 2023 09:01:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235417AbjHNJBI (ORCPT ); Mon, 14 Aug 2023 05:01:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50122 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235561AbjHNJAl (ORCPT ); Mon, 14 Aug 2023 05:00:41 -0400 Received: from xry111.site (xry111.site [89.208.246.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46A773A88 for ; Mon, 14 Aug 2023 02:00:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=xry111.site; s=default; t=1692003615; bh=edGwPpyVyn/vyK03wlum1jlhOhAouMJrXmcB8fOlahk=; h=Subject:From:To:Cc:Date:From; b=jleEd7lwYJIqT6BEXnqjcQbFQseHwE4x6YVeyJeIKQmnq1AlpgpxLKLS42wgg/aMa XlFmswJ40Gl8iNiyW4q/4B/jAaP9bvOdcH26bdCMnvKUduOMwmsS5V4dgz9lvyxO7k 56mf4cAGvuVSRGBmc/Mv3D99innYB3+azTFF/M9Q= Received: from localhost.localdomain (xry111.site [IPv6:2001:470:683e::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-384)) (Client did not present a certificate) (Authenticated sender: xry111@xry111.site) by xry111.site (Postfix) with ESMTPSA id 22A0E659AC; Mon, 14 Aug 2023 05:00:13 -0400 (EDT) Message-ID: <79c179acaa6ec4e1cf112ae2dfce8370694a5089.camel@xry111.site> Subject: Does srso safe RET mitigation require microcode update? From: Xi Ruoyao To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, "Borislav Petkov (AMD)" , Rainer Fiebig Date: Mon, 14 Aug 2023 17:00:12 +0800 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, There seems a difference between Documentation/admin-guide/hw- vuln/srso.rst and the actual behavior. The documentation says: First of all, it is required that the latest microcode be loaded for mitigations to be effective. And: * 'Vulnerable: no microcode': =20 The processor is vulnerable, no microcode extending IBPB functionality to address the vulnerability has been applied. Per the text, if there is no firmware update, the system is just vulnerable. But on a real Zen 3 system, the spec_rstack_overflow file contains "Mitigation: safe RET, no microcode". So we are puzzled now: is this system vulnerable or mitigated? --=20 Xi Ruoyao School of Aerospace Science and Technology, Xidian University