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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 89F65C43140 for ; Thu, 21 Jun 2018 09:46:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4520320883 for ; Thu, 21 Jun 2018 09:46:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4520320883 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 S932806AbeFUJqC (ORCPT ); Thu, 21 Jun 2018 05:46:02 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58406 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932620AbeFUJqA (ORCPT ); Thu, 21 Jun 2018 05:46:00 -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 6AF48448DD; Thu, 21 Jun 2018 09:45:59 +0000 (UTC) Received: from localhost.localdomain (ovpn-12-127.pek2.redhat.com [10.72.12.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1A3361117626; Thu, 21 Jun 2018 09:45:53 +0000 (UTC) Subject: Re: [PATCH 3/4 V3] Remap the device table of IOMMU in encrypted manner for kdump To: Baoquan He Cc: Tom Lendacky , linux-kernel@vger.kernel.org, dyoung@redhat.com, iommu@lists.linux-foundation.org, kexec@lists.infradead.org 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> From: lijiang Message-ID: Date: Thu, 21 Jun 2018 17:45:51 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20180621083915.GE3815@MiWiFi-R3L-srv> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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 [10.11.55.2]); Thu, 21 Jun 2018 09:45:59 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Thu, 21 Jun 2018 09:45:59 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lijiang@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2018年06月21日 16:39, Baoquan He 写道: > 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); > Thank you, Baoquan. I understood what Tom said. I just want to explain why removing the memory encryption mask is necessary before the 'old_devtb_phys >= 0x100000000ULL'. Lianbo > 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." >> >> 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