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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8112BC4332B for ; Thu, 19 Mar 2020 15:44:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AB242072D for ; Thu, 19 Mar 2020 15:44:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584632658; bh=FVF/u9TSzlMdhf4kpAsywZwLbl/sGhd8ENC//u14qkk=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=PldShco0pLPOI9vpX/+wud1dOc4jPejTpJ/cPCbun/CAxB92nNbZChL9qE2tNOflG X9i/GJr+s68pgPkN9ORBglnKriNHt0mYOzNk8sVFxPpEufU+cu+rcNbE+C+CfmwiPk xlgUYaZShFKisY0d2wACcnkpLiFBOVrcB0OFEMCg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728002AbgCSPoR (ORCPT ); Thu, 19 Mar 2020 11:44:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:55468 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727416AbgCSPoR (ORCPT ); Thu, 19 Mar 2020 11:44:17 -0400 Received: from mail-wr1-f53.google.com (mail-wr1-f53.google.com [209.85.221.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7DF1E2072D for ; Thu, 19 Mar 2020 15:44:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584632656; bh=FVF/u9TSzlMdhf4kpAsywZwLbl/sGhd8ENC//u14qkk=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=I0y8sUtct/Bh3UhCYALlKYXq+6n0HLrW6vax7RdHHsEFi5n3GSL+JQMq0m0DjnndW Xnlr5ugUwiw8Ty8NfSG7okzMxvecohY1DohE1VEjUTEVJLbVTbJhrexGrjUrcjgFHl WDAK45zaZZs97psWeLFp4eLJq6uLqm/BJjrLdIjE= Received: by mail-wr1-f53.google.com with SMTP id j17so212981wru.13 for ; Thu, 19 Mar 2020 08:44:16 -0700 (PDT) X-Gm-Message-State: ANhLgQ20PCGEVr/bsPK69IppsPGWdguUdjsMARHXNdxhg+soAu9+TF4U S4IC43wPySOGGXWk9aXGgXI7F28KUtpM0fCs0h9dvg== X-Google-Smtp-Source: ADFU+vu9xO32MybzBmacdPgCqlG7WVDPKTtdn223Fbu4PAIymbvyrGwQMSSWxAV7RNpXhGgQhHa1JuyvGJ5sDsUdXMI= X-Received: by 2002:adf:a30b:: with SMTP id c11mr4940938wrb.257.1584632654996; Thu, 19 Mar 2020 08:44:14 -0700 (PDT) MIME-Version: 1.0 References: <20200319091407.1481-1-joro@8bytes.org> <20200319091407.1481-42-joro@8bytes.org> In-Reply-To: <20200319091407.1481-42-joro@8bytes.org> From: Andy Lutomirski Date: Thu, 19 Mar 2020 08:44:03 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 41/70] x86/sev-es: Add Runtime #VC Exception Handler To: Joerg Roedel Cc: X86 ML , "H. Peter Anvin" , Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , LKML , kvm list , Linux Virtualization , Joerg Roedel Content-Type: text/plain; charset="UTF-8" Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Mar 19, 2020 at 2:14 AM Joerg Roedel wrote: > > From: Tom Lendacky > > Add the handler for #VC exceptions invoked at runtime. If I read this correctly, this does not use IST. If that's true, I don't see how this can possibly work. There at least two nasty cases that come to mind: 1. SYSCALL followed by NMI. The NMI IRET hack gets to #VC and we explode. This is fixable by getting rid of the NMI EFLAGS.TF hack. 2. tools/testing/selftests/x86/mov_ss_trap_64. User code does MOV (addr), SS; SYSCALL, where addr has a data breakpoint. We get #DB promoted to #VC with no stack.