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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30436C6FA82 for ; Sat, 10 Sep 2022 13:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229512AbiIJNn4 (ORCPT ); Sat, 10 Sep 2022 09:43:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229446AbiIJNnx (ORCPT ); Sat, 10 Sep 2022 09:43:53 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6CA23ED62 for ; Sat, 10 Sep 2022 06:43:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A1309B808D6 for ; Sat, 10 Sep 2022 13:43:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 822F9C433D7; Sat, 10 Sep 2022 13:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662817430; bh=tBeZ680+HlTQzJfvNJw3jMyeEy9SyGRGumiy8ZxNN/k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LiS4kh2PSCn9bIjpLqYgxZ94APB3ehxWTQ63zQS3IZFPr7hFNjksC7CxzjlTc+OKz EJhW8dXiUBv8DWw3dw/VdRI1nH80OT4ng8rQs6frXNYd1UEU9MkLXyy39w7FyOra5R is4e2U92PG0p2Z09ZMnFZfMRwxidkThmPfZmBZXa/8ajG72ffFj68ZLAOJ7/8ZOqO8 GxLuXrw4Tqrxx11p2aCxJ4TLH8KV0EvasS9V15p6SYj9dfrGzEXY1wihuiZeVOkH02 6BTk+jID4KzMrZYQTP1ciOS3tXt3leBEH+YgUSg5PFr9xf4Ga4c5wqiuAWXOyQERXn 018CB8DfdL6Mg== Date: Sat, 10 Sep 2022 14:43:44 +0100 From: Will Deacon To: Marc Zyngier Cc: Elliot Berman , Catalin Marinas , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available() Message-ID: <20220910134342.GA959@willie-the-truck> References: <20220909144552.3000716-1-quic_eberman@quicinc.com> <05057e2a-1a85-69ba-ffcd-584d4090467a@quicinc.com> <878rmrr3xw.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878rmrr3xw.wl-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 10, 2022 at 10:09:31AM +0100, Marc Zyngier wrote: > On Fri, 09 Sep 2022 18:55:18 +0100, > Elliot Berman wrote: > > > > > > > > On 9/9/2022 10:28 AM, Catalin Marinas wrote: > > > On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote: > > >> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not > > >> available. This prevents "Protected KVM" cpu capability being reported > > >> when Linux is booting in EL1 and would not have KVM enabled. > > >> > > >> Signed-off-by: Elliot Berman > > >> --- > > >> arch/arm64/kvm/arm.c | 4 +++- > > >> 1 file changed, 3 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > > >> index 8fe73ee5fa84..861f4b388879 100644 > > >> --- a/arch/arm64/kvm/arm.c > > >> +++ b/arch/arm64/kvm/arm.c > > >> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg) > > >> return -EINVAL; > > >> if (strcmp(arg, "protected") == 0) { > > >> - if (!is_kernel_in_hyp_mode()) > > >> + if (!is_hyp_mode_available()) > > >> + kvm_mode = KVM_MODE_DEFAULT; > > > > > > I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want > > > to print a warning instead. > > > > > > > Does it make sense to print warning for kvm-arm.mode=nvhe as well? > > In general, specifying a kvm-arm.mode when no hypervisor mode is > available should be reported as a warning. As long as this is pr_warn() rather than WARN() then I agree. Otherwise, kernels with a kvm-arm.mode hardcoded in CONFIG_CMDLINE (e.g. Android's GKI) will make for noisy guests. Will