Received: by 2002:a05:6a10:1d13:0:0:0:0 with SMTP id pp19csp1276063pxb; Fri, 20 Aug 2021 01:54:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzCvHW1bi5EyQifFuTz1OtFPaSpFXfA8UJIrlLRw+6rrg1mFpJwkYwSAmGk+sRuIX+2pxfx X-Received: by 2002:a02:b091:: with SMTP id v17mr17113498jah.33.1629449654279; Fri, 20 Aug 2021 01:54:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1629449654; cv=none; d=google.com; s=arc-20160816; b=K7Zq+vMpByP+8IhnpzngA1l8kKVUnjp0N7d7WaDadwExMkT0X7vUr/HS+xX3Eh/pk6 TbU8kK9qMswBNbTndF3u8DcfXCqtA87m3NGh32ieCxuj1P4G61VL4q/cFfRQ3dgDAEwl hFSkc3ATuQpW9joq9yPoRoKd+HluDIa0y1aKqFhmp0n6D0KO8S4peUrR7JqgjIIOxaXh 8JEg7Wm8u0J//YQYwdcR5vOcGPnndV3oibi7BduaNDz4BDMYLO7deZezs8wT7ysekScu GHQBVj2t31t5U0887ifwJsz/8/9q3n9M3ya37u1pXiMBZgqbzZ7sQSEPpILNuLqLp7VO tHJA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date; bh=BhxaaQjmDKsY3raw21BHSJ54j9UVdkF3UVYnTuwX+lQ=; b=X11wwXc0pu+oc2iIWnx4nR7BvpmguHueK8ewalGziAEl6nNMXGaDNsZ9N6YgP/x6gb a9y6QwUjdYrwME7yuHkXjRrcHgAT6c2ZRPvlYR6DGDY8u1VGGu0uctV9aY1AjOyggNhW m7lF1xjF+Uv700orRCbblhhfPUGQo9Fw0bf3Mzq33iWX9R0zTklBtldCJUEpJpOr3jlu R+97SMbUJo6t/qUT2ipAYhxBzZywdi6GY/fEDQk6p9GkYds5O4YYZ9941z/86IeJoAfG DzEz36CbkWx/03gS/CK8Rls6WbQQ7Ls3Tih7ckfOGHBlBo1EW1tDz2RYbE1xhelcUjTI X3TA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id l13si5408240jaq.11.2021.08.20.01.54.03; Fri, 20 Aug 2021 01:54:14 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232331AbhHTIxL (ORCPT + 99 others); Fri, 20 Aug 2021 04:53:11 -0400 Received: from 8bytes.org ([81.169.241.247]:37976 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231992AbhHTIxK (ORCPT ); Fri, 20 Aug 2021 04:53:10 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id CB105309; Fri, 20 Aug 2021 10:52:31 +0200 (CEST) Date: Fri, 20 Aug 2021 10:52:26 +0200 From: 'Joerg Roedel' To: David Laight Cc: "x86@kernel.org" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "hpa@zytor.com" , Joerg Roedel , Kees Cook , Andy Lutomirski , Uros Bizjak , Arvind Sankar , Ard Biesheuvel , "linux-kernel@vger.kernel.org" , Fabio Aiuto , "stable@vger.kernel.org" Subject: Re: [PATCH] x86/efi: Restore Firmware IDT in before ExitBootServices() Message-ID: References: <20210820073429.19457-1-joro@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 20, 2021 at 08:43:47AM +0000, David Laight wrote: > Hmmm... > If Linux needs its own IDT then temporarily substituting the old IDT > prior to a UEFI call will cause 'grief' if a 'Linux' interrupt > happens during the UEFI call. This is neede only during very early boot before Linux called ExitBootServices(). Nothing that causes IRQs is set up by Linux yet. Of course the Firmware could have set something up, but Linux runs with IRQs disabled when on its own IDT at that stage. Regards, Joerg