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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 7DE95CAC5A5 for ; Thu, 25 Sep 2025 05:21:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:CC:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1dHu+qfF+j3DIMFKc9HeoPvreOucdAuO+Jk5woaNYdI=; b=mfrJXZ97WNCVEpm0nheF7Nh6JY TSNcIma3dPM6eteeoTiKchrQpFptqoL1HYIYjUgM8I21MpLyxdAUxfwXEcgi1lfs+lMwCTGgUwruO cuqkfG+QKxN4bOgX55JGQjgBP/xX9BNUIeaBPijj6llf6ZFEdRa/MIk5S5VwgOwFuT4hSrRw55B/l PIUKMl4kA5Jn1muOij+tFqshPniDdeScDcOFBMCTGODGlulxY2dY18DoupeCMvQvdMlMTWVxznHeh 5DIMRilemQIgGsFAbdQ7Li6uI9X1RMuYc+jY8dpFNdeDOuvtQL3HAtuaHPobTrHazviQDUa3GcQ6m piRrv/wg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1ePx-00000005pih-0Vbx; Thu, 25 Sep 2025 05:21:21 +0000 Received: from pdx-out-015.esa.us-west-2.outbound.mail-perimeter.amazon.com ([50.112.246.219]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1ePu-00000005phz-2IXR for linux-arm-kernel@lists.infradead.org; Thu, 25 Sep 2025 05:21:19 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1758777678; x=1790313678; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=1dHu+qfF+j3DIMFKc9HeoPvreOucdAuO+Jk5woaNYdI=; b=BrxJ6dZQKzhZ8zrM93yqzUflfUYm7lutPUgAfQvgw963DjZMjvNcJxY2 wE2rKGUTyiOL+MKx3ehJEKJaw+uFUYCcgftzNy8Z6NCBSJy4L4wDmqde+ eOrDl6qIo6bo9JAlrNdQp3ygmpaUtRkb6XlxUS3l82UZxYgz/4noO463O 1PIuU+8Qlge/dSfajF97Hp57ZAYCxzhtQtc4cuCIOvsY6gOdT6xnPCicN 4oBgby82BNJonk2+Pge0hxnFFlqa38G4YpcrvNtB2JwvDk4k33G70+00/ J53LZvRiFyRrONZzGYz9wUdJuhe9E+RO27RdX+t5S6UTNcj/fzUJ5V53w w==; X-CSE-ConnectionGUID: 2sgSshe0QCCvvjHAJKOFKA== X-CSE-MsgGUID: iZZgazSASsCExdr9yR06Mg== X-IronPort-AV: E=Sophos;i="6.18,291,1751241600"; d="scan'208";a="3510852" Received: from ip-10-5-12-219.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.12.219]) by internal-pdx-out-015.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2025 05:21:16 +0000 Received: from EX19MTAUWA001.ant.amazon.com [10.0.21.151:54803] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.48.62:2525] with esmtp (Farcaster) id e01fb47c-faf6-4c81-a5a5-f369ea6453b8; Thu, 25 Sep 2025 05:21:16 +0000 (UTC) X-Farcaster-Flow-ID: e01fb47c-faf6-4c81-a5a5-f369ea6453b8 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWA001.ant.amazon.com (10.250.64.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Thu, 25 Sep 2025 05:21:15 +0000 Received: from c889f3b3a561.amazon.com (10.106.101.18) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Thu, 25 Sep 2025 05:21:15 +0000 From: Priscilla Lam To: CC: , , , , , , , , , , , , Subject: Re: [PATCH] KVM: arm64: Implement KVM_TRANSLATE ioctl for arm64 Date: Wed, 24 Sep 2025 22:21:08 -0700 Message-ID: <20250925052108.27351-1-prl@amazon.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: 86ecrx1px2.wl-maz@kernel.org References: <86ecrx1px2.wl-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.106.101.18] X-ClientProxiedBy: EX19D046UWB004.ant.amazon.com (10.13.139.164) To EX19D001UWA001.ant.amazon.com (10.13.138.214) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250924_222118_646567_F1457907 X-CRM114-Status: UNSURE ( 9.83 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/23/25, 2:26 AM, "Marc Zyngier" wrote: > A guest doing this is a sure indication that it is completely broken, > and will fail on actual HW, because it clearly ignores small > insignificant details such as *ordering*. > > My other question still remains: why can't you perform this page table > walk in userspace? It is actually much safer to do so because you can > stop other vcpus while inspecting the PTs, and avoid a vcpu playing > tricks behind your back -- something the in-kernel PTW doesn't try to > avoid. In our case, this comes from the Windows TPM driver using ldp32 to read static adjacent CRB fields where ordering doesn't matter, but I agree that a guest relying on this kind of translation is problematic. We'll drop this KVM_TRANSLATE implementation and pursue a different approach instead. Thanks, Priscilla