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 E3171C3600B for ; Tue, 25 Mar 2025 16:29:07 +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=kH82AWI1DJslhjV0Iug+U9xXkzn8ELqhzK9jzJCrPWc=; b=Eni5XEzZ2LvooyXBSPVQpt0+ir U1SGkLTZllNFIfADTB5A9zyNriGhNjcThq/z8LB7wjkDaJsCfSuHA0G96KjxdRpU6RTUvCUBMXruG ysvPjsTh2ZZBZKpUExjgILy12Zr5Rv/SijjzjM/DYlAK+xvRnFiStYQGsAGnLwb1scdGaTI41W411 gmbnTwMJn9Dveui0k0wWv1MzJ3YTsQezXe/PLEgEn52Bbe70jI9UxnReL0DitgClvJzF1BqwNeyKh StlMM3PMwOXDbQLRkOVow/pThIqNfhp+6zVf0zz7VasANfT4ChGCuZEJwFB+EIZenM1HSYBxtlHHj Bl/Sh20w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx797-00000006UGk-0Q6P; Tue, 25 Mar 2025 16:28:57 +0000 Received: from out-183.mta0.migadu.com ([2001:41d0:1004:224b::b7]) by bombadil.infradead.org with esmtps (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx71W-00000006SwC-2PYF for linux-arm-kernel@lists.infradead.org; Tue, 25 Mar 2025 16:21:07 +0000 Date: Tue, 25 Mar 2025 09:20:52 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1742919661; 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=kH82AWI1DJslhjV0Iug+U9xXkzn8ELqhzK9jzJCrPWc=; b=M4LypvG3T8toQIUrvERxsZVnUA5+eQ36UPuhS1X6f5JNdlprDLSjniBaiyNKYW/UgQNwIX eaeymRtM4z2Z91mNNqyzNY04RHsh9LpwE+ReNtxrxuPKxKUb8drKWRY5bUZFMHYeAGsQU/ yf4+4dAga4Sy8JusJswBXqZ5pWyO6y8= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Jinqian Yang Cc: maz@kernel.org, yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, wangzhou1@hisilicon.com, shameerali.kolothum.thodi@huawei.com, liuyonglong@huawei.com, jiangkunkun@huawei.com Subject: Re: [PATCH] KVM: arm64: Make HCX writable from userspace Message-ID: References: <20250325121126.1380681-1-yangjinqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250325121126.1380681-1-yangjinqian1@huawei.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250325_092106_755784_4578EA84 X-CRM114-Status: GOOD ( 15.93 ) 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, Mar 25, 2025 at 08:11:26PM +0800, Jinqian Yang wrote: > Allow userspace to modify guest visible value for HCX in > ID_AA64MMFR1_EL1. > > Signed-off-by: Jinqian Yang This is fine, but I would rather we handle all the features like FEAT_HCX instead of a trickle of one-off patches. So, could you please: - Identify all of the features that describe an *EL2* feature which we've exposed to non-nested VMs - Implement patch(es) to make those fields writable (i.e. allow them to be downgraded) - Add corresponding test cases to the set_id_regs selftest Thanks, Oliver > --- > arch/arm64/kvm/sys_regs.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 82430c1e1dd0..b105f156bdf6 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -2666,7 +2666,6 @@ static const struct sys_reg_desc sys_reg_descs[] = { > ID_AA64MMFR0_EL1_TGRAN16_2 | > ID_AA64MMFR0_EL1_ASIDBITS)), > ID_WRITABLE(ID_AA64MMFR1_EL1, ~(ID_AA64MMFR1_EL1_RES0 | > - ID_AA64MMFR1_EL1_HCX | > ID_AA64MMFR1_EL1_TWED | > ID_AA64MMFR1_EL1_XNX | > ID_AA64MMFR1_EL1_VH | > -- > 2.33.0 >