From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:17968 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727245AbfGLV4F (ORCPT ); Fri, 12 Jul 2019 17:56:05 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x6CLqI69085485 for ; Fri, 12 Jul 2019 17:56:03 -0400 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0b-001b2d01.pphosted.com with ESMTP id 2tq1edjewf-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 12 Jul 2019 17:56:03 -0400 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 12 Jul 2019 22:56:02 +0100 References: <20190712053631.9814-1-bauerman@linux.ibm.com> <20190712053631.9814-4-bauerman@linux.ibm.com> <20190712150912.3097215e.pasic@linux.ibm.com> From: Thiago Jung Bauermann Subject: Re: [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code In-reply-to: <20190712150912.3097215e.pasic@linux.ibm.com> Date: Fri, 12 Jul 2019 18:55:47 -0300 MIME-Version: 1.0 Content-Type: text/plain Message-Id: <87tvbqgboc.fsf@morokweng.localdomain> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Halil Pasic Cc: x86@kernel.org, iommu@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Konrad Rzeszutek Wilk , Alexey Dobriyan , Mike Anderson , Ram Pai , "Lendacky, Thomas" [ Cc'ing Tom Lendacky which I forgot to do earlier. Sorry about that. ] Hello Halil, Thanks for the quick review. Halil Pasic writes: > On Fri, 12 Jul 2019 02:36:31 -0300 > Thiago Jung Bauermann wrote: > >> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't >> appear in generic kernel code because it forces non-x86 architectures to >> define the sev_active() function, which doesn't make a lot of sense. > > sev_active() might be just bad (too specific) name for a general > concept. s390 code defines it drives the right behavior in > kernel/dma/direct.c (which uses it). I thought about that but couldn't put my finger on a general concept. Is it "guest with memory inaccessible to the host"? Since your proposed definiton for force_dma_unencrypted() is simply to make it equivalent to sev_active(), I thought it was more straightforward to make each arch define force_dma_unencrypted() directly. Also, does sev_active() drive the right behavior for s390 in elfcorehdr_read() as well? >> To solve this problem, add an x86 elfcorehdr_read() function to override >> the generic weak implementation. To do that, it's necessary to make >> read_from_oldmem() public so that it can be used outside of vmcore.c. >> >> Signed-off-by: Thiago Jung Bauermann >> --- >> arch/x86/kernel/crash_dump_64.c | 5 +++++ >> fs/proc/vmcore.c | 8 ++++---- >> include/linux/crash_dump.h | 14 ++++++++++++++ >> include/linux/mem_encrypt.h | 1 - >> 4 files changed, 23 insertions(+), 5 deletions(-) > > Does not seem to apply to today's or yesterdays master. It assumes the presence of the two patches I mentioned in the cover letter. Only one of them is in master. I hadn't realized the s390 virtio patches were on their way to upstream. I was keeping an eye on the email thread but didn't see they were picked up in the s390 pull request. I'll add a new patch to this series making the corresponding changes to s390's as well. -- Thiago Jung Bauermann IBM Linux Technology Center