From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 7E0DB224B0E for ; Mon, 7 Jul 2025 19:20:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751916005; cv=none; b=EsynePib9o5lH/iAqjNEvYVhlCTK8tYqgOiEeNgWdAM2da1JsmgqMTxD+umJu3ISLtOXCbvoDNNAV1J/91wN9dSuhF0mykxnx7WhCryNCUSUhqyz2tST5/ij38RUHPpFRt5jJ19nvWEN1cqCO9JyNIYgiwFd8BWBRGyjDNoquBA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751916005; c=relaxed/simple; bh=LdO/4LQkEbwgGecFMMdG8I/H4U+/hzTm0h1PFiuavQI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kga43i/a26STD7Z1be5Frgz9FRHetbbFxBFkTdK2SIWCXM679uQtfL+wBASYOSx/srPiNMWkOH42JDuP6YLyCeKXMbln0c5DTRQcwu5pVeVcTUNXEO0aBqwQ1Tk8ZcYo3dbyS6+0jCx8JXFoyIFEBC61hUyL5DLkxTTaFeiUcFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=g4DZ1X0b; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="g4DZ1X0b" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-3132c8437ffso5193794a91.1 for ; Mon, 07 Jul 2025 12:20:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1751916004; x=1752520804; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=oRPungLhCMbFT17gwpSiJyBFIFmaCnbMT4a01H3rmSk=; b=g4DZ1X0baR7HhY2a55J9scQ0n0mv5wZ+GhHeRcsmycD6G6V5leORWiWZW0HwW7ru8/ v1f1MgoQL0tOWqDbeIaHQ4re6UsI1Kt6Ewv48vc0tb4lG4RNLwWWJg911xILbFKElAax +WhLyGpgc425rQTziwrmYrQUVX/ZwQ9ElYXUcKPbyN/KNOmb/i0Tt55GkTsmFGtdp4LD UxRUZe/eUE42OvV/8gp8P2+EuQ5EwHAHzGZE/Tra/LrKRKfOuiwO2T/ngp0zThzOjzFh It2NNE+caafP9ePxLkNCGE0r4n14sBiYrhbagXWWrUeV2JUbZ+ArF9ywwVue0HGwA109 l99Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751916004; x=1752520804; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oRPungLhCMbFT17gwpSiJyBFIFmaCnbMT4a01H3rmSk=; b=HZdhR8CemhjqnX2vw63y+PdlxSAjNmvYPwww0ulXCzNNSKU2DbMCnCdOupB5iQTw8V CiD0tg08uy4D719Lt9RTFjA5IdoB2xBEDkaeoY6X71VzO+nUQ1vgeAqMa1vkCxXZ86sm sdr0WCFIdEFlMfDhDPq2R1xdeDr6D601nDkWtxTZz4Odc22oXANdUvL/+9KqR3nElZpQ QM5mbSAWKXXgYtD6zqtCAQs67zkj5K4u6UAVjo5QTMrJXCUmrtosaJPkAzbvyGKQnnBC qUiM3mzcTbWIhcHI39qAYVU80Q7Ss1zzaB5yVi045kA82T9pxE/xs+6eQBdEzO4i9W3L r/Kg== X-Forwarded-Encrypted: i=1; AJvYcCVLeY1TK1JeYCYKNeWnvjl4F5mFoWXvvNidHJaA6cgEFMmtL0WmKRvK0QSKXYaE4Qb2f8w=@vger.kernel.org X-Gm-Message-State: AOJu0YxwZK6GTNrWqE9VvZMlk9cZ5HXj/2pX7ZLunol//Ddje0RlC8Nw vZRGvrQ6pJkGj+8pVe3bzbReeeHJIUMq9oBHaHIGB0jJlGE5inFQwaY/Clj/yYHPWNT3aJNqy5X BsynREg== X-Google-Smtp-Source: AGHT+IHuZExtBi8nkRDLNH/gGrIUwAHBNEsHmAJ1owCt4iggl3WIus4SV7ghwVoHaOOok8bL/o5LhDmMIuA= X-Received: from pjbpq12.prod.google.com ([2002:a17:90b:3d8c:b0:30e:7783:edb6]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4a81:b0:312:e279:9ccf with SMTP id 98e67ed59e1d1-31aac432867mr18709895a91.5.1751916003788; Mon, 07 Jul 2025 12:20:03 -0700 (PDT) Date: Mon, 7 Jul 2025 12:20:02 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250630133025.4189544-1-alexandre.chartre@oracle.com> <20250701150500.3a4001e9@fedora> Message-ID: Subject: Re: [PATCH] i386/cpu: ARCH_CAPABILITIES should not be advertised on AMD From: Sean Christopherson To: Zhao Liu Cc: Xiaoyao Li , Igor Mammedov , Konrad Rzeszutek Wilk , Alexandre Chartre , qemu-devel@nongnu.org, pbonzini@redhat.com, qemu-stable@nongnu.org, boris.ostrovsky@oracle.com, maciej.szmigiero@oracle.com, kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Wed, Jul 02, 2025, Zhao Liu wrote: > > I think we need firstly aligned on what the behavior of the Windows that hit > > "unsupported processor" is. > > > > My understanding is, the Windows is doing something like > > > > if (is_AMD && CPUID(arch_capabilities)) > > error(unsupported processor) > > This is just a guess; it's also possible that Windows checked this MSR > and found the necessary feature missing. Windows 11 has very strict > hardware support requirements. > > > And I think this behavior is not correct. It's not really a matter of correct versus incorrect in this case. Software is well within its rights to refuse to run on unsupported hardware. E.g. many hypervisors now require EPT/NPT and other modern features. Even KVM requires a minimum set of features; KVM just happens to have a *very* low minimum, and KVM tries to be gentle and friendly when unsupported or incompatible hardware is encountered. Windows' behavior is arguably flawed, misguided, and user hostile, but we can't say it's wrong. E.g. even if the argument is that AMD could ship a future CPU that supports ARCH_CAPABILITIES, it's not a violation of AMD's architecture for Windows to not support such a processor.