From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (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 40FCA1A262A for ; Tue, 9 Sep 2025 05:32:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757395967; cv=none; b=S92TS0ibDYG4mQ/eq3I/fcJ6VKDl9VFC7H1bFNLQByzQ/MhAVLetrIw5rpSl4xsgZSWks4bFG/HKp7/qJ9xc9Ii19DCL9Y2I093xj82koc2NNtfPlDrLrhcGI6vMrlWowZMZ29Be9iQVR59SHPYjmz1NPcX7c2RBO2/P+3Oyoc4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757395967; c=relaxed/simple; bh=imesH7ee1efEYQAis7K/XjX8z18kK0xO5koWlMOvmiI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WNgsrkn25Dna97MO6wy5uEMxaIrbfbFTZYPAf/aHzm1MhtakS4rIhR5KWwaSAw15AhjrI17aBTqTxutY49G5jInk+Y1c4PLZyPecxzEnrN+Ly64n662hmzRugR2uUcgDEJMF7LrSybOnuvCT3Ke5ywzz1DhEDaTKqwV/ei4s3qk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nysw+ADO; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nysw+ADO" 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> 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=us-ascii Content-Disposition: inline In-Reply-To: <20250909034415.3822478-4-yangjinqian1@huawei.com> X-Migadu-Flow: FLOW_OUT 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