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 6E84BC433FE for ; Mon, 13 Dec 2021 14:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238244AbhLMOEB (ORCPT ); Mon, 13 Dec 2021 09:04:01 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:27188 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232193AbhLMOEA (ORCPT ); Mon, 13 Dec 2021 09:04:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639404239; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1AptlvWm8ovvag4ndsPZnTJsnei0DVx3SWRb8MH/REI=; b=czgPCxLwgejaGuEn9FHevlMSUrcO9i9CqCha6GYVyJJdzTOeDvRh5hS7assSym1KDjmh4N 8zryFoJAvjZDkavcHeaYMZpf9H89iWTdyj8iinYji5q96Ebr8Abrz9g8co33zcD65i94Nd J3WHa1yd9rX7cfH0okile1NvG55TYok= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-164-kLNGR4PCP-62LTetQkCMpw-1; Mon, 13 Dec 2021 09:03:56 -0500 X-MC-Unique: kLNGR4PCP-62LTetQkCMpw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 677BC343C9; Mon, 13 Dec 2021 14:03:53 +0000 (UTC) Received: from localhost (ovpn-12-202.pek2.redhat.com [10.72.12.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C4344ADCB; Mon, 13 Dec 2021 14:03:51 +0000 (UTC) Date: Mon, 13 Dec 2021 22:03:48 +0800 From: Baoquan He To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-mm@kvack.org, akpm@linux-foundation.org, hch@lst.de, robin.murphy@arm.com, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, vbabka@suse.cz, m.szyprowski@samsung.com, John.p.donnelly@oracle.com, kexec@lists.infradead.org, rppt@linux.ibm.com Subject: Re: [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages Message-ID: <20211213140348.GA26562@MiWiFi-R3L-srv> References: <20211207030750.30824-1-bhe@redhat.com> <20211207031631.GA5604@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/21 at 02:25pm, Borislav Petkov wrote: > On Tue, Dec 07, 2021 at 11:16:31AM +0800, Baoquan He wrote: > > > This low 1M lock down is needed because AMD SME encrypts memory making > > > the old backup region mechanims impossible when switching into kdump > > > kernel. And Intel engineer mentioned their TDX (Trusted domain extensions) > > > which is under development in kernel also needs lock down the low 1M. > > > So we can't simply revert above commits to fix the page allocation > > > failure from DMA zone as someone suggested. > > Did you read > > f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM") > > carefully for a more generically important reason as to why the first 1M > should not be used? Apparently I didn't. I slacked off and just grabbed things stored in my brain. This is the right justification and missed. Thanks for pointing it out. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwlvs-009ta8-Ax for kexec@lists.infradead.org; Mon, 13 Dec 2021 14:04:01 +0000 Date: Mon, 13 Dec 2021 22:03:48 +0800 From: Baoquan He Subject: Re: [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages Message-ID: <20211213140348.GA26562@MiWiFi-R3L-srv> References: <20211207030750.30824-1-bhe@redhat.com> <20211207031631.GA5604@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-mm@kvack.org, akpm@linux-foundation.org, hch@lst.de, robin.murphy@arm.com, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, vbabka@suse.cz, m.szyprowski@samsung.com, John.p.donnelly@oracle.com, kexec@lists.infradead.org, rppt@linux.ibm.com On 12/13/21 at 02:25pm, Borislav Petkov wrote: > On Tue, Dec 07, 2021 at 11:16:31AM +0800, Baoquan He wrote: > > > This low 1M lock down is needed because AMD SME encrypts memory making > > > the old backup region mechanims impossible when switching into kdump > > > kernel. And Intel engineer mentioned their TDX (Trusted domain extensions) > > > which is under development in kernel also needs lock down the low 1M. > > > So we can't simply revert above commits to fix the page allocation > > > failure from DMA zone as someone suggested. > > Did you read > > f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM") > > carefully for a more generically important reason as to why the first 1M > should not be used? Apparently I didn't. I slacked off and just grabbed things stored in my brain. This is the right justification and missed. Thanks for pointing it out. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec