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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 8EA78C54FCB for ; Mon, 27 Apr 2020 14:37:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 64C0820656 for ; Mon, 27 Apr 2020 14:37:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cB7VnSaO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728052AbgD0Ohi (ORCPT ); Mon, 27 Apr 2020 10:37:38 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:57572 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727834AbgD0Ohh (ORCPT ); Mon, 27 Apr 2020 10:37:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587998256; 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: in-reply-to:in-reply-to:references:references; bh=dI491+uqcVLGhJLl51discOwhIsOK6fPYn0lrj9azwI=; b=cB7VnSaOmPiw8m4FJIsN0lx1YHaSAsMdmaz6Bd8b/kB3b0IqW+C0swfhAv6oh+AgHeWX0t 7a6sScQWYvP7HDSRHpFIdTpC7JtmVHTBRyHy8jQvuuKcYIX3te1p63PwHzzdSGd0rWYVNI w6NoMaQyo4QIics8LSLXP8BbfsHDkwg= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-451--4HO0W6AOVy4fWo7F_h81A-1; Mon, 27 Apr 2020 10:37:34 -0400 X-MC-Unique: -4HO0W6AOVy4fWo7F_h81A-1 Received: by mail-qt1-f198.google.com with SMTP id z3so20636781qtb.6 for ; Mon, 27 Apr 2020 07:37:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dI491+uqcVLGhJLl51discOwhIsOK6fPYn0lrj9azwI=; b=eVSTCKHR2RdnSEFM79XnUwDf6pXszdmbQBLzGFlDuYWlfOKM4TE10WAP/VVZTG13a8 gWaqOV/DXKVsCnWTfDhD8qucUw+suMakDZfzBnrw5u/dWj0DNl174phXhz2bFUfTJOnR CXx7H4VS6NoynOgpZpukzc9+F7l/nnKTVguiH1XqPPuwbsmkJ/DjL0YPDwechJCo6PLV er1gVgLf8hWoS21D4zNTRUPXz4hSAAD9gIvaSXrk0ZTPWw10l2QFCbSKRl0ZDGT5rMP3 yul/WL8x4aYYKSB1sgFYt0coCKrZfcOiWRoZCNbWBfsYRAQ7qfwLGX8R9oIAfEOJtBoW qHDw== X-Gm-Message-State: AGi0PuYWNZ1Dc6i91GPj7awqmHA04XowbY8NKxsnfL3SoyoSl+MseNxF 0YSYNM2wTnVDkdscspcIoqOfm1CZ7kL3jFUC+msK/6sNKXFxGwHHMWFNIGLYoJrRPF2dXJKlyZP XUU8GQ4bsWDFNE+lYEenUJUO+ X-Received: by 2002:ac8:70c9:: with SMTP id g9mr23361870qtp.375.1587998254324; Mon, 27 Apr 2020 07:37:34 -0700 (PDT) X-Google-Smtp-Source: APiQypJ3MOntIHO6GU9G0j7CB5hrTg6E4pfYWNz7v8nCSIxAIx1xDbSwwoNvtfL/Bg7I4pCVzDsSUw== X-Received: by 2002:ac8:70c9:: with SMTP id g9mr23361839qtp.375.1587998254074; Mon, 27 Apr 2020 07:37:34 -0700 (PDT) Received: from xz-x1 ([2607:9880:19c0:32::2]) by smtp.gmail.com with ESMTPSA id c6sm10441899qka.58.2020.04.27.07.37.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2020 07:37:33 -0700 (PDT) Date: Mon, 27 Apr 2020 10:37:32 -0400 From: Peter Xu To: Paolo Bonzini Cc: Sean Christopherson , Xiaoyao Li , kvm@vger.kernel.org, Nadav Amit , Vitaly Kuznetsov , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 1/3] kvm: x86: Rename KVM_DEBUGREG_RELOAD to KVM_DEBUGREG_NEED_RELOAD Message-ID: <20200427143732.GD48376@xz-x1> References: <20200416101509.73526-1-xiaoyao.li@intel.com> <20200416101509.73526-2-xiaoyao.li@intel.com> <20200423190941.GN17824@linux.intel.com> <20200424202103.GA48376@xz-x1> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 25, 2020 at 09:48:17AM +0200, Paolo Bonzini wrote: > On 24/04/20 22:21, Peter Xu wrote: > > But then shouldn't DIRTY be set as long as KVM_DEBUGREG_BP_ENABLED is set every > > time before vmenter? Then it'll somehow go back to switch_db_regs, iiuc... > > > > IIUC RELOAD actually wants to say "reload only for this iteration", that's why > > it's cleared after each reload. So maybe... RELOAD_ONCE? > > > > (Btw, do we have debug regs tests somewhere no matter inside guest or with > > KVM_SET_GUEST_DEBUG?) > > What about KVM_DEBUGREG_EFF_DB_DIRTY? The problem is iiuc we always reload eff_db[] no matter which bit in switch_db_regs is set, so this may still not clearly identify this bit from the rest of the two bits... Actually I think eff_db[] is a bit confusing here in that it can be either the host specified dbreg values or the guest specified depends on the dynamic value of KVM_GUESTDBG_USE_HW_BP. I am thinking maybe it's clearer to have host_db[] and guest_db[], then only until vmenter do we load either of them by: if (KVM_GUESTDBG_USE_HW_BP) load(host_db[]); else load(gueet_db[]); Then each db[] will be very clear on what's the data is about. And we don't need to check KVM_GUESTDBG_USE_HW_BP every time when accessing eff_db[]. > > We have them in kvm-unit-tests for debug regs inside the guest, but no > selftests covering KVM_SET_GUEST_DEBUG. I see! Thanks, -- Peter Xu