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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8984ECF58C6 for ; Wed, 19 Nov 2025 18:09:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vLmc0-0002ax-CX; Wed, 19 Nov 2025 13:09:00 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLmbw-0002Yk-Nq for qemu-devel@nongnu.org; Wed, 19 Nov 2025 13:08:57 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLmbv-0002s2-82 for qemu-devel@nongnu.org; Wed, 19 Nov 2025 13:08:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763575734; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=e4w9qUfBPNqlHWR761GYigXjDzqbKAXHlPl3evsHnXw=; b=GGqP+m6VlK9mD75IymC6NURH7KSIVt2genZbGTXZyyEmeki4f5vvXOBYEUS4xI/5wNMR64 +Ecsc9XsQ6Zn0lQLU8QTO5GPa6lZtUuoL66Z/5Plu67zLFEH0CGNJir52z40TemMH9GMik 5ArStutX0DNMns4zFIxJwGL8Y3PhBiU= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-26-x1qFzs0-MJWlbiph_J5JDQ-1; Wed, 19 Nov 2025 13:08:52 -0500 X-MC-Unique: x1qFzs0-MJWlbiph_J5JDQ-1 X-Mimecast-MFC-AGG-ID: x1qFzs0-MJWlbiph_J5JDQ_1763575732 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-429c93a28ebso14486f8f.1 for ; Wed, 19 Nov 2025 10:08:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1763575731; x=1764180531; darn=nongnu.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=e4w9qUfBPNqlHWR761GYigXjDzqbKAXHlPl3evsHnXw=; b=hGgh/bWLiBiGGCEkNjkmJYT0NNJR6xZ2kbznOgqtAufpxLBDN4GO7Ydz1wCW0vlTtG 0H1zMPvb5aJ5utLZ8IUJyo6JQ2Z0JGvi3B3kfp4kb88agpxUfympSYUvcp1XJ94Y9cD3 75fDhKqyYHhPq0iXjc9jCAMycitmjySnLBERpicht74L66IPX/brGrv0L561HDUC9U7J BpfDlFH1Ouc0tCQApmz/iBjjYxw5/tgngw7a/ByPY1F/4E0MlNtCrXmGphedNKAuk2AD HMbqkZFjfnIdCMvfpDw5BYmlr81RcA/3LpTLiDZoDWYBhX37luEINSXikNslz9/eumLt PJCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763575731; x=1764180531; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=e4w9qUfBPNqlHWR761GYigXjDzqbKAXHlPl3evsHnXw=; b=TXd7xvZGa84nytpsTeML+IDiszByKDWDFBD5fgItJlNNcUKIUpGQdvoUEoAl438GeJ gHKuOOs8lVq0sxJATTKVZHVRCIyO+iCtkzSriZlUviQgxJqr828x05YqVTDrxBRjYxob TC0MR4Mxvf4cl7BOCkMqGiMA/qx0K7YjzH1MFH0fgX6sosvhciqeyXdTmkJICcsbvsVm rtCCeeTUKpxmmYvkRatVhEC08EoAyQ9EmSaSAk6l1XGk+HFgzHjXA3RZ3QFUArvvU+r1 Rcp1Ew4RCyiAGYT4YjStYlQD5l6A7TE8AAospVXkWRUz46ePgK8OhbWOteuRT0DTCp9E gkhA== X-Forwarded-Encrypted: i=1; AJvYcCVKJ1MAoKJyLb6OL6sS/+ig0N7Bo2azvPur+GadVEu5oWJdZvvcZDI5woDyfAwsg7mvRB8jq9ne/5DR@nongnu.org X-Gm-Message-State: AOJu0YyRSe4AHkVEpbiTZdTLl43T7/dJfM9UJYxKbD9gCPE+CLlIx4MP jzHffMzzE7E0UcS4Dvezg2ZTRZLHJnU0lFTBz6wmr0eUxMGDoketLfgVJLaq09JvXBmbcNVX6MD ZPj9NkIpRV7SOPZkKnujR33nlXT61JqAjHEI3fX5v166zg7g3S0ycwL6TyV/jcAOXSuTo74lYbT /1mM4sZ1GwS3RYtq4UjCJUO9PZSgpqrL0= X-Gm-Gg: ASbGnctP8gof6JW/YfwI6v7XuvOP7xN6Q0o/sSfpMBSfh8hjf2oiuXrDi276Fw9vYMu RsWXIYyrlTPWIEdPXZiAzVgFxegw+UaNxR5fHYWcmlC0wxMoceYjgx51RvYoEMxA/oBUOcl4vG6 +XxFXhsHwU/OvrVgk47pT6+3/80IhLdFOa4I/FF0Y1DqnjtGocrlR6JlkBYls2jp0Hx88ogOMwh ir7ylbRpNjmCCXyyiajqCZGjtsX8jWCl4S3sk4yvqXmsJfdIXIpzp+s8iRcNsZ8a4l5YNY= X-Received: by 2002:a05:6000:40de:b0:429:8daa:c6b4 with SMTP id ffacd0b85a97d-42b593497d8mr19539690f8f.21.1763575731484; Wed, 19 Nov 2025 10:08:51 -0800 (PST) X-Google-Smtp-Source: AGHT+IEFM3+HiCKuo+MB8yCGXu3hopFkEu2pEqFtoOTpey/HAF3kWb7fs4h9KqgFD0kfB73wWdRQReAFNiiZ+raP7ac= X-Received: by 2002:a05:6000:40de:b0:429:8daa:c6b4 with SMTP id ffacd0b85a97d-42b593497d8mr19539669f8f.21.1763575731072; Wed, 19 Nov 2025 10:08:51 -0800 (PST) MIME-Version: 1.0 References: <20251118065817.835017-1-zhao1.liu@intel.com> <20251118065817.835017-5-zhao1.liu@intel.com> In-Reply-To: From: Paolo Bonzini Date: Wed, 19 Nov 2025 19:08:36 +0100 X-Gm-Features: AWmQ_bnP_jPIBa_pCEhGrRI1O_HVzZjEH7dyW6CfW-AYdWmRuTyzlIIDNIWUIl8 Message-ID: Subject: Re: [PATCH 4/5] i386/cpu: Support APX CPUIDs To: Florian Weimer Cc: Zhao Liu , qemu-devel@nongnu.org, kvm@vger.kernel.org, "Chang S . Bae" , Zide Chen , Xudong Hao , Peter Fang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Nov 19, 2025 at 7:04=E2=80=AFPM Florian Weimer = wrote: > This sentence (from APX spec rev.7) emphasizes the =E2=80=9CIntel=E2=80= =9D vendor, > > and its primary goal was to address and explain compatibility concern > > for pre-enabling work based on APX spec v6. Prior to v7, APX included > > NCI_NDD_NF by default, but this feature has now been separated from > > basic APX and requires explicit checking CPUID bit. > > > > x86 ecosystem advisory group has aligned on APX so it may be possible > > for other x86 vendors to implement APX without NCI_NDD_NF and this stil= l > > match with the APX spec. > > Well yes, but I doubt that the ecosystem will produce binaries > specialized for APX *without* NDD. It's fine to enumerate it > separately, but that doesn't have any immediate consequences. GCC makes > it rather hard to build for APX without NDD, for example. At least more > difficult than building for AVX-512F without AVX-512VL. > > I just don't think software vendors are enthusiastic about having to > create and support not one, but two builds for APX. If NDD is optional > in practice, it will not be possible to use it except for run-time > generated code and perhaps very targeted optimizations because that > single extra APX will just not use NDD. > > I feel like there has been a misunderstanding somewhere. I totally agree and I think this addition to APX was very misguided, no matter who proposed it. However, for virtualization we probably should include this code no matter how much I dislike it, because having to add the bit later retroactively would be worse. Paolo