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=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 9E7E1C07E9C for ; Fri, 9 Jul 2021 16:36:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84F1F613C5 for ; Fri, 9 Jul 2021 16:36:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229632AbhGIQit (ORCPT ); Fri, 9 Jul 2021 12:38:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60848 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229487AbhGIQis (ORCPT ); Fri, 9 Jul 2021 12:38:48 -0400 Received: from mail-ot1-x333.google.com (mail-ot1-x333.google.com [IPv6:2607:f8b0:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F03ADC0613DD for ; Fri, 9 Jul 2021 09:36:03 -0700 (PDT) Received: by mail-ot1-x333.google.com with SMTP id w8-20020a0568304108b02904b3da3d49e5so6018448ott.1 for ; Fri, 09 Jul 2021 09:36:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=KPJc57zXKNbmm6Wda6Wo2yhPL66N0K7mX7Ni/9wA22A=; b=MLhRmhg31B/NqMjA2W3smAusHRT7XDvc2hG4HgIGIn0JTGEdMDa45XXhOMirJW1j4E CwQteVMF1OM0UkapniXaSksq8EBVbqXIHhLkmN2KY3s7i1uJ13FxA2dMGLRejl4H836E 59dTDDPVDkxWC/s+vYz9Pn7andHFbqorbs3C97CpJt8ameRLbeKfzFT2KHZV+IwSHmH/ VsiwT9OSNAK6jezJJzPy3UEUTe/dWCAKFob1CDk2u5RsbyR+YlhUQbiEHBpbqw87y1Nw W8k9sgwbLdpgTS27koSUOrVv41azZR7wU1tmMVTeequSaY2NKWTK7nmREjnTaWt6EkDt 2MKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KPJc57zXKNbmm6Wda6Wo2yhPL66N0K7mX7Ni/9wA22A=; b=XVmHshUs1bio/BFKxE4bnwLGp3nKxCUtT+Oww+mVOJxlzCxqFC+l8gvPJ7XxgT0j6o hGe6Slblc4e48cJekaGytYGyiieL9SRxVvRgGY4Q1W5IzwflzDQlHPxgBbk8gyzxw5gj SGbN8uUS31aBGsHYzDZNZ3ir5iPhZTuinZZZ1mnTQ8WwMvVKYey1snFUhP+ggW1i6H3Q slmpBuY4mhAcH7EMZuTVYQmPLD1KPmdbF8QnlU2xN6MqV+yDmf7Hi/rXKPYUDi1KRyTI FSZcuWUzuVj2awezYcKwKuH1dX6lb7+TaNW+JrlZxGqvIBZdoGT7Dsvk4kFvGhay4duO Tvyg== X-Gm-Message-State: AOAM533VyaKMgw1jjAj2YlUOZLyielSZAdSDlUy9CGUfF1vO7sDkwuJG ELEKi6+qPbzgkbCe731QpU6F1VJs/KKvvZeFWe/UKQ== X-Google-Smtp-Source: ABdhPJzmi7sJ7IjCj6kOY34d6qrQNMR5UNqyGmph22ptlmZ5SLYcWRXGTXDYBGh3Qm9ILS/PCo+NwsupNOdicOaAmU8= X-Received: by 2002:a9d:550e:: with SMTP id l14mr30228676oth.241.1625848563120; Fri, 09 Jul 2021 09:36:03 -0700 (PDT) MIME-Version: 1.0 References: <20210628172632.81029-1-jiangshanlai@gmail.com> <46e0aaf1-b7cd-288f-e4be-ac59aa04908f@redhat.com> <397a448e-ffa7-3bea-af86-e92fbb273a07@redhat.com> <01946b5a-9912-3dfb-36f0-031f425432d2@redhat.com> In-Reply-To: <01946b5a-9912-3dfb-36f0-031f425432d2@redhat.com> From: Jim Mattson Date: Fri, 9 Jul 2021 09:35:30 -0700 Message-ID: Subject: Re: [PATCH] KVM: X86: Also reload the debug registers before kvm_x86->run() when the host is using them To: Paolo Bonzini Cc: Lai Jiangshan , Lai Jiangshan , linux-kernel@vger.kernel.org, Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 9, 2021 at 8:52 AM Paolo Bonzini wrote: > > On 09/07/21 12:05, Lai Jiangshan wrote: > > > > > > On 2021/7/9 17:49, Paolo Bonzini wrote: > >> On 09/07/21 05:09, Lai Jiangshan wrote: > >>> I just noticed that emulation.c fails to emulate with DBn. > >>> Is there any problem around it? > >> > >> Just what you said, it's not easy and the needs are limited. I > >> implemented kvm_vcpu_check_breakpoint because I was interested in > >> using hardware breakpoints from gdb, even with unrestricted_guest=0 > >> and invalid guest state, but that's it. > > > > It seems kvm_vcpu_check_breakpoint() handles only for code breakpoint > > and doesn't handle for data breakpoints. > > Correct, there's a comment above the call. But data breakpoint are much > harder and relatively less useful. Data breakpoints are actually quite useful. I/O breakpoints not so much. > > And no code handles DR7_GD bit when the emulation is not resulted from > > vm-exit. (for example, the non-first instruction when kvm emulates > > instructions back to back and the instruction accesses to DBn). > > Good point, that should be fixed too. > > Paolo >