From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-106100.protonmail.ch (mail-106100.protonmail.ch [79.135.106.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CE48155C97 for ; Mon, 12 Oct 2026 00:31:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=79.135.106.100 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791765097; cv=none; b=Q1PDfyKaqPEyvAaf7ncAE1VmXNbEfam8iLcrJu9dsKdlEfo9TU4ln6OFlN3ScLBVzK7QRZ2zG3Td/kr2V0qG1gyC++3a7KwjaWp17K3U4vvf7r8w+qSNDxV8XfWzVYp5n4ji7PHcVtNChTruoQbBJOnBfyZdyaTBXbwX8yFduQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791765097; c=relaxed/simple; bh=RUXX/8LcvZ0vB1NfOTbwuI0qJ0UfI9cCnFbhhtoelG0=; h=Date:To:From:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=bS4FG9nOAUQi7QeaSOs6YIEkQiB0zacbDqUw0Bv4TIrA/SC+FCFTqY+SMDoO+SwDtTWbbO95dAayLRnKDfT1faqRq8QJgob3EczbZ8O+ZUMh5UoLMIYfMENaIwAGX2xzJ1UHa4DOy0XUndWtqAnmcFuQEdzqzkqodwUEvLD5frQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=turntrout.com; spf=pass smtp.mailfrom=turntrout.com; dkim=pass (2048-bit key) header.d=turntrout.com header.i=@turntrout.com header.b=UEFk7vRp; arc=none smtp.client-ip=79.135.106.100 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=turntrout.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=turntrout.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=turntrout.com header.i=@turntrout.com header.b="UEFk7vRp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=turntrout.com; s=protonmail2; t=1791765086; x=1792024286; bh=IraLLtnBNwHo1dM/C9RlUNjtzUQvG9INhNh3pggIMIc=; h=Date:To:From:Cc:Subject:Message-ID:Feedback-ID:From:To:Cc:Date: Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=UEFk7vRpRCSPplihQDiOD1uO6ySs+QMPaxpFBTtGFzM52D4r012i+QTpgMsMbJb5E EudQ8AppMjgbI1g9hMRpU4WZnJBhlIqcRfPwQNFiJSRj3Y83DNjFVM89ryfzBYYTLW 42peD8xg4hWQAh02dwu41N4oAJlOOkwvP/CYnIzXgUvm1OVS0AoFlmPz1LZPu1zKiM MDlqOv0HBJvI5+tGc078l+FsF0igFRwedzX5D7JjsYe0cr4okybh2j5Ibl2r2gC31i lWTjFkhzGsjNls6LSeMK9ZtZ7D4iYBbnZUZnAMsNWFwXDx7PQUFujy3ZYGYVY9qqVl 6QV9AqKHzstsQ== Date: Mon, 12 Oct 2026 00:31:21 +0000 To: Paolo Bonzini From: Alex Turner Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, nsaenz@amazon.com, vkuznets@redhat.com, snambakam@linux.microsoft.com Subject: Re: [PATCH v3 00/28] KVM: x86: Introduce memory protection attributes Message-ID: <20261012003036.61996-1-alex@turntrout.com> Feedback-ID: 110371027:user:proton X-Pm-Message-ID: 68202226d966a1c20801d528891e7db282e9f536 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable A second user, with no guest cooperation: we run untrusted AI coding agents in Cloud Hypervisor microVMs, and the host builds the guest kernel. We would set NW on its text after boot, so that a ring-0 write exits to the VMM as tamper evidence. Two questions: 1. Does NX distinguish supervisor from user execution? Without that, ring 0 can copy its text to an unprotected GFN and repoint its page tables. Is MBEC/GMET-backed NX planned, or should the VMM write-protect guest page tables? 2. For the emulator EFAULT gap you noted in patch 26: will a write the emulator performs on an NW gfn always exit? We can test the series from Cloud Hypervisor if that helps.