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 B0E10C9832F for ; Mon, 28 Sep 2026 08:05:41 +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-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=th1IQ7Uvi9M8PQvb4aBCWvyzqIApqDWa0UnRnSg5hFU=; b=KmvV307dp7pEjyacTve15BJXMT rhcksyXEoDf9BLfnycdyMyOG03erGNCX3OnK8zj3EdEMOOz8qJciRa6vv175M7tyGmZhOpRRq6Tne eUaLmWIwgXj8paxsjrHbQr2mWFKx3mFejtM3Ydy2MrZb4AJMnpUR828f3bX369Uq3jXRQcBf8Ur4n qzQu+7FaDzJvbU01tNyGt/YYNlTMyz1KLpxEQ1LMKDXY14P6w2qJZH5EQRlYgEpeumDF9KGgexc02 clj6OYqibp31ATfC/HWlxGYNknUk/ubM8thkyQxlRR1vFvA90yH9fYcDVtdNMH1/KTZKmtB0eowaV d0SJv4uw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB6Mh-0000000019U-0bsQ; Mon, 28 Sep 2026 08:05:35 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xB6Md-0000000018Z-3tJD for linux-arm-kernel@lists.infradead.org; Mon, 28 Sep 2026 08:05:33 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 72046169E; Mon, 28 Sep 2026 01:05:24 -0700 (PDT) Received: from [10.57.12.79] (unknown [10.57.12.79]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 949CB3F86F; Mon, 28 Sep 2026 01:05:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790582727; bh=ZoYd2sdPRi7PYnEG0IlvFGd13KoF/WZCPDZleG3Y+cw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GZFpwPFl7ovI3rDNT/2mn4+w0i4sXv4nTmdNKJvdtEoZbukSO66jtaCM+F9CsbXdb ZQvnQ+cf9fHw3YVxkeX+xcls+suLYnK7BcC2DCPEW+ZevQmsUlgnB7EwYSwF+Huj6z s6cD2Zr1h9Xg0ltB6Jac4THbkfTIu9l/lUMJZmoE= Message-ID: <88bd2049-d25b-4767-81f8-83c99749fd11@arm.com> Date: Mon, 28 Sep 2026 09:05:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v19 2/7] firmware: arm_rmm: Check for RMI support at init Content-Language: en-GB To: Marc Zyngier Cc: Catalin Marinas , kvm@vger.kernel.org, kvmarm@lists.linux.dev, will@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, gshan@redhat.com, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, sudeep.holla@arm.com, jonathan.cameron@oss.qualcomm.com References: <20260924135201.850038-1-suzuki.poulose@arm.com> <20260924135201.850038-3-suzuki.poulose@arm.com> <87v77r2ga5.wl-maz@kernel.org> From: Suzuki K Poulose In-Reply-To: <87v77r2ga5.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260928_010532_271305_3797E648 X-CRM114-Status: GOOD ( 13.31 ) 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 27/09/2026 10:29, Marc Zyngier wrote: > On Fri, 25 Sep 2026 16:23:49 +0100, > Suzuki K Poulose wrote: >> >> On 25/09/2026 11:42, Catalin Marinas wrote: >>> On Thu, Sep 24, 2026 at 02:51:56PM +0100, Suzuki K Poulose wrote: >>>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c >>>> index 32102c3912fa7..e8b29983b0021 100644 >>>> --- a/arch/arm64/kernel/cpufeature.c >>>> +++ b/arch/arm64/kernel/cpufeature.c >>>> @@ -293,6 +293,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar3[] = { >>>> static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { >>>> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV3_SHIFT, 4, 0), >>>> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_CSV2_SHIFT, 4, 0), >>>> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_RME_SHIFT, 4, 0), >>> >>> I think we end up exposing this to (any) guest unless we mask it out in >>> sanitise_id_aa64dfr0_el1(). Do the guests care about the RME version? I >> >> Valid point. I personally don't think this matters. The FEAT_RME alone >> is not useful or harmful. I could mask it in KVM as a safe bet. > > Is there *any* case where the guest (realm or not) should know it is > running on RME enabled HW? I can perfectly imagine that someone would We don't do that for Linux Guests at least. The Realms rely on the presence of RSI ABI. Cheers Suzuki > implement something looking like CCA on non-RME systems. > > M. >