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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50731C43143 for ; Fri, 22 Jun 2018 02:52:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0204A23C7F for ; Fri, 22 Jun 2018 02:52:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0204A23C7F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934276AbeFVCwo (ORCPT ); Thu, 21 Jun 2018 22:52:44 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58538 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933914AbeFVCwn (ORCPT ); Thu, 21 Jun 2018 22:52:43 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 68D9E4015199; Fri, 22 Jun 2018 02:52:43 +0000 (UTC) Received: from localhost (ovpn-8-18.pek2.redhat.com [10.72.8.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CEEAD1117652; Fri, 22 Jun 2018 02:52:40 +0000 (UTC) Date: Fri, 22 Jun 2018 10:52:35 +0800 From: Baoquan He To: Tom Lendacky Cc: lijiang , kexec@lists.infradead.org, iommu@lists.linux-foundation.org, dyoung@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4 V3] Remap the device table of IOMMU in encrypted manner for kdump Message-ID: <20180622025235.GN29979@MiWiFi-R3L-srv> References: <20180616082714.32035-1-lijiang@redhat.com> <20180616082714.32035-4-lijiang@redhat.com> <60c6f00e-0eb3-d39c-6a1e-8a1dc1e095af@amd.com> <20180621083915.GE3815@MiWiFi-R3L-srv> <4c71ac2a-5c53-f1b1-8de6-4b7b944d5d06@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4c71ac2a-5c53-f1b1-8de6-4b7b944d5d06@amd.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 22 Jun 2018 02:52:43 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 22 Jun 2018 02:52:43 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'bhe@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/21/18 at 08:12am, Tom Lendacky wrote: > On 6/21/2018 3:39 AM, Baoquan He wrote: > > On 06/21/18 at 01:42pm, lijiang wrote: > >> 在 2018年06月21日 00:42, Tom Lendacky 写道: > >>> On 6/16/2018 3:27 AM, Lianbo Jiang wrote: > >>>> In kdump mode, it will copy the device table of IOMMU from the old > >>>> device table, which is encrypted when SME is enabled in the first > >>>> kernel. So we must remap it in encrypted manner in order to be > >>>> automatically decrypted when we read. > >>>> > >>>> Signed-off-by: Lianbo Jiang > >>>> --- > >>>> Some changes: > >>>> 1. add some comments > >>>> 2. clean compile warning. > >>>> > >>>> drivers/iommu/amd_iommu_init.c | 15 ++++++++++++++- > >>>> 1 file changed, 14 insertions(+), 1 deletion(-) > >>>> > >>>> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c > >>>> index 904c575..a20af4c 100644 > >>>> --- a/drivers/iommu/amd_iommu_init.c > >>>> +++ b/drivers/iommu/amd_iommu_init.c > >>>> @@ -889,11 +889,24 @@ static bool copy_device_table(void) > >>>> } > >>>> > >>>> old_devtb_phys = entry & PAGE_MASK; > >>>> + > >>>> + /* > >>>> + * When sme enable in the first kernel, old_devtb_phys includes the > >>>> + * memory encryption mask(sme_me_mask), we must remove the memory > >>>> + * encryption mask to obtain the true physical address in kdump mode. > >>>> + */ > >>>> + if (mem_encrypt_active() && is_kdump_kernel()) > >>>> + old_devtb_phys = __sme_clr(old_devtb_phys); > >>>> + > >>> > >>> You can probably just use "if (is_kdump_kernel())" here, since memory > >>> encryption is either on in both the first and second kernel or off in > >>> both the first and second kernel. At which point __sme_clr() will do > >>> the proper thing. > >>> > >>> Actually, this needs to be done no matter what. When doing either the > >>> ioremap_encrypted() or the memremap(), the physical address should not > >>> include the encryption bit/mask. > >>> > >>> Thanks, > >>> Tom > >>> > >> Thanks for your comments. If we don't remove the memory encryption mask, it will > >> return false because the 'old_devtb_phys >= 0x100000000ULL' may become true. > > > > Lianbo, you may not get what Tom suggested. Tom means no matter what it > > is, encrypted or not in 1st kernel, we need get pure physicall address, > > and using below code is always right for both cases. > > > > if (is_kdump_kernel()) > > old_devtb_phys = __sme_clr(old_devtb_phys); > > > > And this is simpler. You even can add one line of code comment to say > > like "Physical address w/o encryption mask is needed here." > > Even simpler, there's no need to even check for is_kdump_kernel(). The > __sme_clr() should always be done if the physical address is going to be > used for some form of io or memory remapping. > > So you could just change the existing: > > old_devtb_phys = entry & PAGE_MASK; > > to: > > old_devtb_phys = __sme_clr(entry) & PAGE_MASK; Agree, this is even better. > > >> > >> Lianbo > >>>> if (old_devtb_phys >= 0x100000000ULL) { > >>>> pr_err("The address of old device table is above 4G, not trustworthy!\n"); > >>>> return false; > >>>> } > >>>> - old_devtb = memremap(old_devtb_phys, dev_table_size, MEMREMAP_WB); > >>>> + old_devtb = (mem_encrypt_active() && is_kdump_kernel()) > >>>> + ? (__force void *)ioremap_encrypted(old_devtb_phys, > >>>> + dev_table_size) > >>>> + : memremap(old_devtb_phys, dev_table_size, MEMREMAP_WB);> + > >>>> if (!old_devtb) > >>>> return false; > >>>> > >>>> > >> > >> _______________________________________________ > >> kexec mailing list > >> kexec@lists.infradead.org > >> http://lists.infradead.org/mailman/listinfo/kexec > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec