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 3142FC00140 for ; Wed, 24 Aug 2022 18:43:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239752AbiHXSnQ (ORCPT ); Wed, 24 Aug 2022 14:43:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232226AbiHXSnL (ORCPT ); Wed, 24 Aug 2022 14:43:11 -0400 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B0DD7A761; Wed, 24 Aug 2022 11:43:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661366591; x=1692902591; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=6eT7fMb+dHOWan1/ECU9slGyuY/ttLNe4NtX2rjpGl0=; b=P0+wXy29db0FReQCPOhxw+WMqLieGJdlSDL7lZE+yLkv2xA8o1NAwYui kELcD19gvgXlHOS0lu4V5VV8rGlrAFAPxIqzz/BAE0jHKgDBOtoKuxlbu Tlvbj11Ez1dbhwbFmDzCJZJ6OAnwREH+iFBn5B9AvWefgoe5BFnZ19feE AIvXfYiFAcpT0wIN8wHcqNStrOIwodR3cPtFb1T7JH43Q6wvzaZe2iArY 34wkt6Cut5+MnA6hJc0v6/rXqWdIdlGuyDy60oLiehrmORrBkYdSu2qpw QuWxiwqSiOv6TiSYqJajRS/yMT2NI1675e08rkOAS+2+1uvVHQqWOZAne Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10449"; a="274436973" X-IronPort-AV: E=Sophos;i="5.93,261,1654585200"; d="scan'208";a="274436973" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2022 11:43:11 -0700 X-IronPort-AV: E=Sophos;i="5.93,261,1654585200"; d="scan'208";a="938022285" Received: from skeshri-mobl.ger.corp.intel.com (HELO [10.212.154.182]) ([10.212.154.182]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2022 11:43:10 -0700 Message-ID: <10bc452f-3564-e41b-836d-e135a8f4260d@intel.com> Date: Wed, 24 Aug 2022 11:43:10 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] x86/sev: Don't use cc_platform_has() for early SEV-SNP calls Content-Language: en-US To: Tom Lendacky , linux-kernel@vger.kernel.org, x86@kernel.org Cc: Borislav Petkov , Thomas Gleixner , Ingo Molnar , Dave Hansen , "H. Peter Anvin" , Asish Kalra , Michael Roth , Joerg Roedel , "Kirill A. Shutemov" , stable@vger.kernel.org, Sean Christopherson References: <0c9b9a6c33ff4b8ce17a87a6c09db44d3b52bad3.1661291751.git.thomas.lendacky@amd.com> From: Dave Hansen In-Reply-To: <0c9b9a6c33ff4b8ce17a87a6c09db44d3b52bad3.1661291751.git.thomas.lendacky@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/23/22 14:55, Tom Lendacky wrote: > When running identity mapped and depending on the kernel configuration, > it is possible that cc_platform_has() can have compiler generated code > that uses jump tables. This causes a boot failure because the jump table > uses un-mapped kernel virtual addresses, not identity mapped addresses. > This has been seen with CONFIG_RETPOLINE=n. So, we don't have *ANY* control over where the compiler uses jump tables. The kernel just happened to add some code that uses them, fell over, and this adds a hack to get booting again. Isn't this a bigger problem?