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 DD0A1CAC587 for ; Tue, 9 Sep 2025 06:58:49 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=imesH7ee1efEYQAis7K/XjX8z18kK0xO5koWlMOvmiI=; b=swkRSTgEnLjvQDAImbaiZQ0aPZ vGYKkJBtFjSAjkI46fNxl66OC3L79RDvCaa15ssDVm34swIe+WQz3zOoI///gIXTKndrX44KwQ34u kKcTbHS22Exuj1pI+diEqPDshVaELE1z4v5S+icLk0vlOhVwGGg20THby+XrfRGuqSdt1cUmxJUbA P9shRHsWSRXKoKDFoVCmJ4gl3hOqc3ZJ59cWOKNwmYS5Xpe7ycBlxboK7IV/xAQowg4QT++aBV3nX 03mY0H6Ahtv1/jFzelhmL8pW9Y4pUwTCzYVRSjHSQbk1IntLjj14Sn28Bh6E2UXrwHn+hp3K5Ju9b 8YQULdng==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uvsJN-00000004yt2-3uE5; Tue, 09 Sep 2025 06:58:42 +0000 Received: from out-172.mta0.migadu.com ([2001:41d0:1004:224b::ac]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uvqyE-00000004RTm-2fKz for linux-arm-kernel@lists.infradead.org; Tue, 09 Sep 2025 05:32:48 +0000 Date: Mon, 8 Sep 2025 22:32:35 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757395962; 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: in-reply-to:in-reply-to:references:references; bh=imesH7ee1efEYQAis7K/XjX8z18kK0xO5koWlMOvmiI=; b=nysw+ADOUYBJhMYLzPVCtQSvTHBZoDKuq6+zkvVv/H9ua8HqZtlH/oAXQJwrXPNwcPwIWq lgPISzjIK+CMqjeUfpElrtoNDNgkDE823Vo0Em8mBp3zeg37tT27DSktVcMb1X0HHmgOzW rd97cI6mO25B3ViXjDfLEeqWdEfbOqI= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Jinqian Yang Cc: yuzenghui@huawei.com, maz@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, liuyonglong@huawei.com, wangzhou1@hisilicon.com Subject: Re: [PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1_EL1.VH writable from userspace Message-ID: References: <20250909034415.3822478-1-yangjinqian1@huawei.com> <20250909034415.3822478-4-yangjinqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250909034415.3822478-4-yangjinqian1@huawei.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250908_223247_171884_768C40D1 X-CRM114-Status: UNSURE ( 7.64 ) 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 Hi Jinqian, On Tue, Sep 09, 2025 at 11:44:15AM +0800, Jinqian Yang wrote: > Allow userspace to downgrade VH in ID_AA64MMFR1_EL1. Userspace can > only change this value from high to low. I'm afraid we can't allow this. When we expose FEAT_VHE to the VM, HCR_EL2.E2H is RES1. Meaning, vEL2 is unconditionally in a VHE context. I would be OK with a clarifying comment documenting why the field is non-writable. Thanks, Oliver