From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A9AA60A2638 for ; Tue, 20 Oct 2026 08:46:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=xenproject.org header.i=@xenproject.org header.a=rsa-sha256 header.s=20200302mail header.b=Nvzp+N3U Received: from list by lists.xenproject.org with outflank-mailman.1455185.1668746 (Exim 4.92) (envelope-from ) id 1xJ5Tr-0000ee-1l; Tue, 20 Oct 2026 08:45:59 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1455185.1668746; Tue, 20 Oct 2026 08:45:59 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1xJ5Tq-0000eX-Uv; Tue, 20 Oct 2026 08:45:58 +0000 Received: by outflank-mailman (input) for mailman id 1455185; Tue, 20 Oct 2026 08:45:57 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1xJ5Tp-0000eM-RA for xen-devel@lists.xenproject.org; Tue, 20 Oct 2026 08:45:57 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.98.2) (envelope-from ) id 1xJ5Tp-00000003eYH-2DEF; Tue, 20 Oct 2026 08:45:57 +0000 Received: from 224.pool85-54-217.dynamic.orange.es ([85.54.217.224] helo=localhost) by xenbits.xenproject.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1xJ5Tp-00000005YG5-0k13; Tue, 20 Oct 2026 08:45:57 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Post: List-Help: List-Subscribe: , Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xenproject.org; s=20200302mail; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=tExn8gEWG18jx/rCO3HfzBEnybQkBY44c4vBPT9MoA4=; b=Nvzp+N3U+xdHoyxOsUKEkDeY6L TacZ+V+uAPgcDmQCd+HEIapkVNka8IckSkF8x4H+KK1hF9n+b2xL2iPlDLpsOw9WykL60ha0Pn4TD 7v0eU0YD7s7AHDzdVNFVQu6QugPyKjd7CM48FFvwhAAPdtu+6RDmOhB0Y6YI91yijQfc=; Date: Tue, 20 Oct 2026 10:45:51 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Andrew Cooper Cc: Xen-devel , Jan Beulich , Teddy Astie Subject: Re: [PATCH] x86/shstk: Fix possible crash while enabling Shadow Stacks Message-ID: References: <20261019155959.883789-1-andrew.cooper3@citrix.com> <5916f3aa-a008-4233-a562-d091eeb9dc7c@citrix.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5916f3aa-a008-4233-a562-d091eeb9dc7c@citrix.com> X-Spam-Status: No, score=-11.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 20, 2026 at 09:31:17AM +0100, Andrew Cooper wrote: > On 19/10/2026 7:58 pm, Roger Pau Monné wrote: > > On Mon, Oct 19, 2026 at 04:59:59PM +0100, Andrew Cooper wrote: > >> Between writing MSR_S_CET.SHSTK_EN and establishing SSP using RSTORSSP or > >> SETSSBSY, there must not be any CALL or RET instructions. > >> > >> Building Xen with -fno-early-inlining causes wrmsr() to become out-of-line, > >> and thus suffers #DF during boot. > >> > >> Make the MSR and shstk helpers always_inline. They ought to have been this > >> way all along. > >> > >> Reported-by: Roger Pau Monné > >> Signed-off-by: Andrew Cooper > > Sorry seems like I'm a bit slow today. Also worth adding: > > > > Fixes: b60ab42db2f0 ("x86/shstk: Activate Supervisor Shadow Stacks"). > > If we're doing that, we need > > Fixes: 3037d8b7eb3e ("x86/boot: Use RSTORSSP to establish SSP") Fine with me, I just went for the first instance, and didn't care for the FRED one. Thanks, Roger.