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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 A7EA1C433E6 for ; Mon, 31 Aug 2020 10:27:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AC6020936 for ; Mon, 31 Aug 2020 10:27:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="V08T2Weq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726523AbgHaK1L (ORCPT ); Mon, 31 Aug 2020 06:27:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726248AbgHaK1J (ORCPT ); Mon, 31 Aug 2020 06:27:09 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABBC7C061573; Mon, 31 Aug 2020 03:27:08 -0700 (PDT) Received: from zn.tnic (p200300ec2f085000329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ec:2f08:5000:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 31A0E1EC02F2; Mon, 31 Aug 2020 12:27:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1598869626; 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: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=ZuWmCteGQZKM0ko0ElODot8ukDLVFBwRtcdceTKHyJE=; b=V08T2WeqYCMhRjX3D5H2r4EqFkI0JVoF2Ohes825PrLzETVPYkLxl1GPEn/7TSpDZdWzbp 8UU4qAGxRwPluiQYH2jRl0uT9qfcF9eCrrfw4Kf6Zk2aeZzG/dgYcnPaS16JfQ63jhp5ya pEpx11HroUZ5WqYtb7XAL7poJus3OKU= Date: Mon, 31 Aug 2020 12:27:01 +0200 From: Borislav Petkov To: Joerg Roedel Cc: x86@kernel.org, Joerg Roedel , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v6 45/76] x86/sev-es: Allocate and Map IST stack for #VC handler Message-ID: <20200831102701.GE27517@zn.tnic> References: <20200824085511.7553-1-joro@8bytes.org> <20200824085511.7553-46-joro@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200824085511.7553-46-joro@8bytes.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Aug 24, 2020 at 10:54:40AM +0200, Joerg Roedel wrote: > From: Joerg Roedel > > Allocate and map an IST stack and an additional fall-back stack for > the #VC handler. The memory for the stacks is allocated only when > SEV-ES is active. > > The #VC handler needs to use an IST stack because it could be raised > from kernel space with unsafe stack, e.g. in the SYSCALL entry path. > > Since the #VC exception can be nested, the #VC handler switches back to > the interrupted stack when entered from kernel space. If switching back > is not possible the fall-back stack is used. > > Signed-off-by: Joerg Roedel > Link: https://lore.kernel.org/r/20200724160336.5435-45-joro@8bytes.org > --- > arch/x86/include/asm/cpu_entry_area.h | 33 +++++++++++++++++---------- > arch/x86/include/asm/page_64_types.h | 1 + > arch/x86/kernel/cpu/common.c | 2 ++ > arch/x86/kernel/dumpstack_64.c | 8 +++++-- > arch/x86/kernel/sev-es.c | 33 +++++++++++++++++++++++++++ > 5 files changed, 63 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h > index 8902fdb7de13..f87e4c0c16f4 100644 > --- a/arch/x86/include/asm/cpu_entry_area.h > +++ b/arch/x86/include/asm/cpu_entry_area.h > @@ -11,25 +11,29 @@ > #ifdef CONFIG_X86_64 > > /* Macro to enforce the same ordering and stack sizes */ > -#define ESTACKS_MEMBERS(guardsize) \ > - char DF_stack_guard[guardsize]; \ > - char DF_stack[EXCEPTION_STKSZ]; \ > - char NMI_stack_guard[guardsize]; \ > - char NMI_stack[EXCEPTION_STKSZ]; \ > - char DB_stack_guard[guardsize]; \ > - char DB_stack[EXCEPTION_STKSZ]; \ > - char MCE_stack_guard[guardsize]; \ > - char MCE_stack[EXCEPTION_STKSZ]; \ > - char IST_top_guard[guardsize]; \ > +#define ESTACKS_MEMBERS(guardsize, optional_stack_size) \ > + char DF_stack_guard[guardsize]; \ > + char DF_stack[EXCEPTION_STKSZ]; \ > + char NMI_stack_guard[guardsize]; \ > + char NMI_stack[EXCEPTION_STKSZ]; \ > + char DB_stack_guard[guardsize]; \ > + char DB_stack[EXCEPTION_STKSZ]; \ > + char MCE_stack_guard[guardsize]; \ > + char MCE_stack[EXCEPTION_STKSZ]; \ > + char VC_stack_guard[guardsize]; \ > + char VC_stack[optional_stack_size]; \ > + char VC2_stack_guard[guardsize]; \ > + char VC2_stack[optional_stack_size]; \ So the VC* stuff needs to be ifdefferied and enabled only on CONFIG_AMD_MEM_ENCRYPT... here and below. I had that in my previous review too: "All those things should be under an CONFIG_AMD_MEM_ENCRYPT ifdeffery." > + char IST_top_guard[guardsize]; \ > > /* The exception stacks' physical storage. No guard pages required */ > struct exception_stacks { > - ESTACKS_MEMBERS(0) > + ESTACKS_MEMBERS(0, 0) > }; > > /* The effective cpu entry area mapping with guard pages. */ > struct cea_exception_stacks { > - ESTACKS_MEMBERS(PAGE_SIZE) > + ESTACKS_MEMBERS(PAGE_SIZE, EXCEPTION_STKSZ) > }; > > /* > @@ -40,6 +44,8 @@ enum exception_stack_ordering { > ESTACK_NMI, > ESTACK_DB, > ESTACK_MCE, > + ESTACK_VC, > + ESTACK_VC2, > N_EXCEPTION_STACKS > }; > > @@ -139,4 +145,7 @@ static inline struct entry_stack *cpu_entry_stack(int cpu) > #define __this_cpu_ist_top_va(name) \ > CEA_ESTACK_TOP(__this_cpu_read(cea_exception_stacks), name) > > +#define __this_cpu_ist_bot_va(name) \ "bottom" please. I was wondering for a bit, what "bot"? And I know it is CEA_ESTACK_BOT but that's not readable. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette