From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A2DE225A50 for ; Thu, 27 Feb 2025 21:10:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740690624; cv=none; b=n15hrCpVd8bNCspXDjNme0D1hlbCEhNCryoCRNGe3ENdKIgZX1oPnWkUVuqTZbbW71ySrNrYdfj8krvOK1O1NrRJ/78xiAE1ni7z558ZUQwSForXRVElyGeO730ENCAqub6uBqvTdthoQwrf9IsugaM5PwoAE3jIqEF1BrPZfas= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740690624; c=relaxed/simple; bh=0EcUyBKZhTLQR3BYkYQDdRQDQ7f2tsUeTeRa4PvAtV4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fea6F9HcTXXpXmEmPAaHgvYwf/8ffcIlyFK7d4K1mnhTEMgNyy9hoplt1SJc4wnldxjk0A0Gs8Gpir0j9aaE3hs9Uhl5xrE0+/8bI+hlhAyS4EJrkmcdmdN/jmdTZKoMSpXKcNv8gvvuQaXWiltPQZyaGX5t4tZjXn4MppLOYg0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=citrix.com; spf=pass smtp.mailfrom=cloud.com; dkim=pass (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b=VB1WuXHK; arc=none smtp.client-ip=209.85.221.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=citrix.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cloud.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="VB1WuXHK" Received: by mail-wr1-f43.google.com with SMTP id ffacd0b85a97d-38f504f087eso1021693f8f.1 for ; Thu, 27 Feb 2025 13:10:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1740690621; x=1741295421; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=McVDA02T8ChyltXMoGQz21UDmm2WB9bHt1FmktyqO9g=; b=VB1WuXHKBRFvNWav7ZbGBLkSPGATk50qjSOBIqx5EGGsKGsSgFe6FG5jKXev51DA7p kRzl0jlbMg8C+WarGL7wFavg4oPoZE/LMCGsSywryS0ObkLCpFgu+VniNfkZ9ilxAE52 Uzi7iXqzuEkx704jpSFyTkbaSbkAh7gzzdPGU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740690621; x=1741295421; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=McVDA02T8ChyltXMoGQz21UDmm2WB9bHt1FmktyqO9g=; b=ork89SeRQLg7KXSnkt1JeudZUX2PAFkETNSKIau62HqsPgj6fcyfynFxzSDgoyGev3 WjzPRpK+Xr7SKsmqmbxqt8HY1kq8jTLCT3CcB0uBhsxFdw1c+ALXLHXmcSFSGzsK93Lm W49FD9exCJFukkf+e5shm6u+gv/pEwU+PAijao+DXk7gEwK4SdWV9y7v9IWenlEuSRP7 gZVINAAvvhBSC6xIwIcRQuYYJNuFjddkGXG2vAIX+3W7H5htWucliNk4vA0/aaiGBOWp H+RTtomDWyyF8XuL5petjcJMwbLo+3OLJlhCfqqP9fewpt5BS94yWK7GW2Ub0ggm90ak aW/w== X-Forwarded-Encrypted: i=1; AJvYcCVcpigMWC69OsFJ+uwtVwSAWrv3OQbu/uK5KsQwlW1qu7+30CCR6MuAlvj0TsFWv3OVFsc5FuG/s5zYloE=@vger.kernel.org X-Gm-Message-State: AOJu0Yx/x7LT/8XMYumeBbPeP42pfMO7DLWT03rykJup2ep/sNgKOSHU cmuOmLDIhPRdI7ILkPmTgszIzYD6Gj92+NtIB1jkd+Obumvku4pB2IxT++A/iFM= X-Gm-Gg: ASbGncvAdVJI7zqvUCbtdaq97hM/bSrYIXK6Xo2Pm/fTW6/agyGO+LWfYQhhgiWA6BC z5tKmu1P5og6VQX8qHOF/up8B6mAsaq+VmhLFOD1TUcQ4skduFO++K1sycu7Sh3wl+Z29zRGtCG kq08gyA/an/QCdkdPBlHxs81D6RECNUcBmaWMjXGCPxodfWv95Q+jK5XiqAMCnkjcPmVTyqiGll +BBGE/i4fU64h7TMnB6V1qTkYyrj5MWoI2OzApnKX56m7tq0+YIMFNAMLnPHQmGfg6Nv6XyFmXu JROFg/3fQN4kM1+6xbngDS0jRKjQSUUrvN09Gpmf461l+G3qdwpFQQbO3pGLk5/X/w== X-Google-Smtp-Source: AGHT+IFgQt1PVzqZnm4g8KGhIwZcUHnnyirC4gn2Ce/wzGC6Yq6y2mLyVO1IOZ3rKalzE2d9OwQfoQ== X-Received: by 2002:a5d:47cd:0:b0:38d:e481:c680 with SMTP id ffacd0b85a97d-390ec9bb569mr584403f8f.18.1740690620844; Thu, 27 Feb 2025 13:10:20 -0800 (PST) Received: from [192.168.1.10] (host-92-26-98-202.as13285.net. [92.26.98.202]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-390e47b7d69sm3196795f8f.60.2025.02.27.13.10.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Feb 2025 13:10:20 -0800 (PST) Message-ID: Date: Thu, 27 Feb 2025 21:10:19 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v1 02/11] x86/fpu/xstate: Introduce xstate order table and accessor macro To: Ingo Molnar Cc: bp@alien8.de, chang.seok.bae@intel.com, dave.hansen@intel.com, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, x86@kernel.org References: <94083f1c-dab1-4b57-bd45-a4d4f8ac262e@citrix.com> Content-Language: en-GB From: Andrew Cooper Autocrypt: addr=andrew.cooper3@citrix.com; keydata= xsFNBFLhNn8BEADVhE+Hb8i0GV6mihnnr/uiQQdPF8kUoFzCOPXkf7jQ5sLYeJa0cQi6Penp VtiFYznTairnVsN5J+ujSTIb+OlMSJUWV4opS7WVNnxHbFTPYZVQ3erv7NKc2iVizCRZ2Kxn srM1oPXWRic8BIAdYOKOloF2300SL/bIpeD+x7h3w9B/qez7nOin5NzkxgFoaUeIal12pXSR Q354FKFoy6Vh96gc4VRqte3jw8mPuJQpfws+Pb+swvSf/i1q1+1I4jsRQQh2m6OTADHIqg2E ofTYAEh7R5HfPx0EXoEDMdRjOeKn8+vvkAwhviWXTHlG3R1QkbE5M/oywnZ83udJmi+lxjJ5 YhQ5IzomvJ16H0Bq+TLyVLO/VRksp1VR9HxCzItLNCS8PdpYYz5TC204ViycobYU65WMpzWe LFAGn8jSS25XIpqv0Y9k87dLbctKKA14Ifw2kq5OIVu2FuX+3i446JOa2vpCI9GcjCzi3oHV e00bzYiHMIl0FICrNJU0Kjho8pdo0m2uxkn6SYEpogAy9pnatUlO+erL4LqFUO7GXSdBRbw5 gNt25XTLdSFuZtMxkY3tq8MFss5QnjhehCVPEpE6y9ZjI4XB8ad1G4oBHVGK5LMsvg22PfMJ ISWFSHoF/B5+lHkCKWkFxZ0gZn33ju5n6/FOdEx4B8cMJt+cWwARAQABzSlBbmRyZXcgQ29v cGVyIDxhbmRyZXcuY29vcGVyM0BjaXRyaXguY29tPsLBegQTAQgAJAIbAwULCQgHAwUVCgkI CwUWAgMBAAIeAQIXgAUCWKD95wIZAQAKCRBlw/kGpdefoHbdD/9AIoR3k6fKl+RFiFpyAhvO 59ttDFI7nIAnlYngev2XUR3acFElJATHSDO0ju+hqWqAb8kVijXLops0gOfqt3VPZq9cuHlh IMDquatGLzAadfFx2eQYIYT+FYuMoPZy/aTUazmJIDVxP7L383grjIkn+7tAv+qeDfE+txL4 SAm1UHNvmdfgL2/lcmL3xRh7sub3nJilM93RWX1Pe5LBSDXO45uzCGEdst6uSlzYR/MEr+5Z JQQ32JV64zwvf/aKaagSQSQMYNX9JFgfZ3TKWC1KJQbX5ssoX/5hNLqxMcZV3TN7kU8I3kjK mPec9+1nECOjjJSO/h4P0sBZyIUGfguwzhEeGf4sMCuSEM4xjCnwiBwftR17sr0spYcOpqET ZGcAmyYcNjy6CYadNCnfR40vhhWuCfNCBzWnUW0lFoo12wb0YnzoOLjvfD6OL3JjIUJNOmJy RCsJ5IA/Iz33RhSVRmROu+TztwuThClw63g7+hoyewv7BemKyuU6FTVhjjW+XUWmS/FzknSi dAG+insr0746cTPpSkGl3KAXeWDGJzve7/SBBfyznWCMGaf8E2P1oOdIZRxHgWj0zNr1+ooF /PzgLPiCI4OMUttTlEKChgbUTQ+5o0P080JojqfXwbPAyumbaYcQNiH1/xYbJdOFSiBv9rpt TQTBLzDKXok86M7BTQRS4TZ/ARAAkgqudHsp+hd82UVkvgnlqZjzz2vyrYfz7bkPtXaGb9H4 Rfo7mQsEQavEBdWWjbga6eMnDqtu+FC+qeTGYebToxEyp2lKDSoAsvt8w82tIlP/EbmRbDVn 7bhjBlfRcFjVYw8uVDPptT0TV47vpoCVkTwcyb6OltJrvg/QzV9f07DJswuda1JH3/qvYu0p vjPnYvCq4NsqY2XSdAJ02HrdYPFtNyPEntu1n1KK+gJrstjtw7KsZ4ygXYrsm/oCBiVW/OgU g/XIlGErkrxe4vQvJyVwg6YH653YTX5hLLUEL1NS4TCo47RP+wi6y+TnuAL36UtK/uFyEuPy wwrDVcC4cIFhYSfsO0BumEI65yu7a8aHbGfq2lW251UcoU48Z27ZUUZd2Dr6O/n8poQHbaTd 6bJJSjzGGHZVbRP9UQ3lkmkmc0+XCHmj5WhwNNYjgbbmML7y0fsJT5RgvefAIFfHBg7fTY/i kBEimoUsTEQz+N4hbKwo1hULfVxDJStE4sbPhjbsPCrlXf6W9CxSyQ0qmZ2bXsLQYRj2xqd1 bpA+1o1j2N4/au1R/uSiUFjewJdT/LX1EklKDcQwpk06Af/N7VZtSfEJeRV04unbsKVXWZAk uAJyDDKN99ziC0Wz5kcPyVD1HNf8bgaqGDzrv3TfYjwqayRFcMf7xJaL9xXedMcAEQEAAcLB XwQYAQgACQUCUuE2fwIbDAAKCRBlw/kGpdefoG4XEACD1Qf/er8EA7g23HMxYWd3FXHThrVQ HgiGdk5Yh632vjOm9L4sd/GCEACVQKjsu98e8o3ysitFlznEns5EAAXEbITrgKWXDDUWGYxd pnjj2u+GkVdsOAGk0kxczX6s+VRBhpbBI2PWnOsRJgU2n10PZ3mZD4Xu9kU2IXYmuW+e5KCA vTArRUdCrAtIa1k01sPipPPw6dfxx2e5asy21YOytzxuWFfJTGnVxZZSCyLUO83sh6OZhJkk b9rxL9wPmpN/t2IPaEKoAc0FTQZS36wAMOXkBh24PQ9gaLJvfPKpNzGD8XWR5HHF0NLIJhgg 4ZlEXQ2fVp3XrtocHqhu4UZR4koCijgB8sB7Tb0GCpwK+C4UePdFLfhKyRdSXuvY3AHJd4CP 4JzW0Bzq/WXY3XMOzUTYApGQpnUpdOmuQSfpV9MQO+/jo7r6yPbxT7CwRS5dcQPzUiuHLK9i nvjREdh84qycnx0/6dDroYhp0DFv4udxuAvt1h4wGwTPRQZerSm4xaYegEFusyhbZrI0U9tJ B8WrhBLXDiYlyJT6zOV2yZFuW47VrLsjYnHwn27hmxTC/7tvG3euCklmkn9Sl9IAKFu29RSo d5bD8kMSCYsTqtTfT6W4A3qHGvIDta3ptLYpIAOD2sY3GYq2nf3Bbzx81wZK14JdDDHUX2Rs 6+ahAA== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 27/02/2025 8:06 pm, Ingo Molnar wrote: > * Andrew Cooper wrote: >> What options #1 and #4 will cause is the virt people to come after >> you with sharp implements for creating incompatibilities in an ABI.  >> The XFEATUREs are the tag(ish) of the union that is the xsave buffer. > There's no incompatibility for a default-disabled feature that gets > enabled by an AVX-aware host kernel and by AVX-aware guest kernels. > What ABI would be broken? I don't understand your question. XSAVE, and details about in CPUID, are a stated ABI (given in the SDM and APM), and available in userspace, including for userpace to write into a file/socket and interpret later (this is literally how we migrate VMs between different hosts). You simply redefine what %xcr0.bnd_* (a.k.a. XFEATURES 3 and 4) mean, irrespective of what a guest kernel thinks it can get away with. ~Andrew