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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,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 C3B2EC43382 for ; Wed, 26 Sep 2018 07:33:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82A5A208E4 for ; Wed, 26 Sep 2018 07:33:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82A5A208E4 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 S1727338AbeIZNod (ORCPT ); Wed, 26 Sep 2018 09:44:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52304 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726951AbeIZNoc (ORCPT ); Wed, 26 Sep 2018 09:44:32 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6015330820DE; Wed, 26 Sep 2018 07:32:59 +0000 (UTC) Received: from localhost (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B25B260BE1; Wed, 26 Sep 2018 07:32:55 +0000 (UTC) Date: Wed, 26 Sep 2018 15:32:52 +0800 From: Baoquan He To: Borislav Petkov Cc: "Lendacky, Thomas" , Kairui Song , "Singh, Brijesh" , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "hpa@zytor.com" , "tglx@linutronix.de" , "dyoung@redhat.com" Subject: Re: [PATCH] x86/boot: Fix kexec booting failure after SEV early boot support Message-ID: <20180926073252.GC2555@MiWiFi-R3L-srv> References: <20180925111020.23834-1-kasong@redhat.com> <6e15796e-31e9-2dc6-4a31-5c1b01554b45@amd.com> <20180925172608.GB15464@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180925172608.GB15464@zn.tnic> User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Wed, 26 Sep 2018 07:32:59 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/25/18 at 07:26pm, Borislav Petkov wrote: > IINM, the problem can be addressed in a simpler way by getting rid of > enc_bit and thus getting rid of the need to do relative addressing of > anything and simply doing the whole dance of figuring out the C-bit each > time. It probably wouldn't be even measurable... Couldn't agree more. Obviously enc_bit is redundent here. We only check eax each time, removing it can fix the RIP-relative addressing issue in kexec. diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S index eaa843a52907..0b60eb867d25 100644 --- a/arch/x86/boot/compressed/mem_encrypt.S +++ b/arch/x86/boot/compressed/mem_encrypt.S @@ -27,19 +27,6 @@ ENTRY(get_sev_encryption_bit) push %edx push %edi - /* - * RIP-relative addressing is needed to access the encryption bit - * variable. Since we are running in 32-bit mode we need this call/pop - * sequence to get the proper relative addressing. - */ - call 1f -1: popl %edi - subl $1b, %edi - - movl enc_bit(%edi), %eax - cmpl $0, %eax - jge .Lsev_exit - /* Check if running under a hypervisor */ movl $1, %eax cpuid @@ -69,12 +56,10 @@ ENTRY(get_sev_encryption_bit) movl %ebx, %eax andl $0x3f, %eax /* Return the encryption bit location */ - movl %eax, enc_bit(%edi) jmp .Lsev_exit .Lno_sev: xor %eax, %eax - movl %eax, enc_bit(%edi) .Lsev_exit: pop %edi @@ -113,9 +98,6 @@ ENTRY(set_sev_encryption_mask) ENDPROC(set_sev_encryption_mask) .data -enc_bit: - .int 0xffffffff - #ifdef CONFIG_AMD_MEM_ENCRYPT .balign 8 GLOBAL(sme_me_mask)