From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EBE9771 for ; Wed, 16 Jun 2021 19:01:32 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id 5BDFA387; Wed, 16 Jun 2021 21:01:31 +0200 (CEST) Date: Wed, 16 Jun 2021 21:01:30 +0200 From: Joerg Roedel To: Peter Zijlstra Cc: x86@kernel.org, Joerg Roedel , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v5 3/6] x86/sev-es: Split up runtime #VC handler for correct state tracking Message-ID: References: <20210614135327.9921-1-joro@8bytes.org> <20210614135327.9921-4-joro@8bytes.org> X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Peter, sorry, missed this email before sending out v6. On Wed, Jun 16, 2021 at 06:04:26PM +0200, Peter Zijlstra wrote: > On Mon, Jun 14, 2021 at 03:53:24PM +0200, Joerg Roedel wrote: > > _ASM_NOKPROBE(\asmsym) > > SYM_CODE_END(\asmsym) > > Consistency with idtentry_mce_db would seem to suggest using \cfunc and > noist_\cfunc. > > amluto, tglx: do we have strong feelings on consistency? Yeah, but this distinction does not make sense here, as none of the #VC handlers C functions run on the actual #VC IST stack. The from-kernel function might run on the fall-back stack (not really possible today unless the hypervisor does something nasty). And the difference between the fall-back stack and the actual IST stack is, that on the fall-back stack nesting #VC exceptions is still supported. > > + vc_handle_trap_db(regs); > > It's a bit sad this does user_mode(regs) again. Okay, I will change this according your comments. Thanks, Joerg 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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 2655FC48BE8 for ; Wed, 16 Jun 2021 19:01:37 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BBD2361245 for ; Wed, 16 Jun 2021 19:01:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBD2361245 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 809BE83B97; Wed, 16 Jun 2021 19:01:36 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lbLtaHtCD3oZ; Wed, 16 Jun 2021 19:01:35 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 2DBF883B43; Wed, 16 Jun 2021 19:01:35 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id F2500C000E; Wed, 16 Jun 2021 19:01:34 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 316D6C000B for ; Wed, 16 Jun 2021 19:01:34 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 170C983B97 for ; Wed, 16 Jun 2021 19:01:34 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id c1qhxZvBxAvx for ; Wed, 16 Jun 2021 19:01:33 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by smtp1.osuosl.org (Postfix) with ESMTPS id 7A05A83B43 for ; Wed, 16 Jun 2021 19:01:33 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id 5BDFA387; Wed, 16 Jun 2021 21:01:31 +0200 (CEST) Date: Wed, 16 Jun 2021 21:01:30 +0200 From: Joerg Roedel To: Peter Zijlstra Subject: Re: [PATCH v5 3/6] x86/sev-es: Split up runtime #VC handler for correct state tracking Message-ID: References: <20210614135327.9921-1-joro@8bytes.org> <20210614135327.9921-4-joro@8bytes.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: kvm@vger.kernel.org, Dave Hansen , virtualization@lists.linux-foundation.org, Arvind Sankar , hpa@zytor.com, Jiri Slaby , x86@kernel.org, David Rientjes , Martin Radev , Tom Lendacky , Joerg Roedel , Kees Cook , Cfir Cohen , linux-coco@lists.linux.dev, Andy Lutomirski , Dan Williams , Juergen Gross , Mike Stunes , Sean Christopherson , linux-kernel@vger.kernel.org, Masami Hiramatsu , Erdem Aktas X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" Hi Peter, sorry, missed this email before sending out v6. On Wed, Jun 16, 2021 at 06:04:26PM +0200, Peter Zijlstra wrote: > On Mon, Jun 14, 2021 at 03:53:24PM +0200, Joerg Roedel wrote: > > _ASM_NOKPROBE(\asmsym) > > SYM_CODE_END(\asmsym) > > Consistency with idtentry_mce_db would seem to suggest using \cfunc and > noist_\cfunc. > > amluto, tglx: do we have strong feelings on consistency? Yeah, but this distinction does not make sense here, as none of the #VC handlers C functions run on the actual #VC IST stack. The from-kernel function might run on the fall-back stack (not really possible today unless the hypervisor does something nasty). And the difference between the fall-back stack and the actual IST stack is, that on the fall-back stack nesting #VC exceptions is still supported. > > + vc_handle_trap_db(regs); > > It's a bit sad this does user_mode(regs) again. Okay, I will change this according your comments. Thanks, Joerg _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization