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 5A94AC55162 for ; Mon, 3 Aug 2026 03:52:26 +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=3CMlvQhl0gYlAXDo46EPh67i5t6YesQnwh40HahRwS0=; b=zF1LA07faZsYhYvrHfd9L3ZjQU TD2At8+o+nfkvobI5tGrd2VZeLzIn35f//hOo424RB4Uk5lv4If+yXIdgHzNQBIr/DLXsjcHLthE2 fxmNgOsP/Axk6l/g+AU91eA6+u5MFBM0QungjjSjd95Bc9ZkpyFKMW6VI9DbaJ+ENJnJqGVt7eCOo /YFyqcbin97W9Vk/IiWDZvcndI/GHpUjfpW25gou4gUQb/T4MHFS28KhxNtIYFyXDLq0ck0kK2q+4 g2QxLeOM1Hsx5Qlz26Fwux+2JDQMEuzwPdgULzomYQNjX3OG6HZlisHZA/d80tGro/9zpZ9IMgn0Y c0nsEL+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqjin-0000000GGBC-28wa; Mon, 03 Aug 2026 03:52:13 +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 1wqjik-0000000GGAa-1Art for linux-arm-kernel@lists.infradead.org; Mon, 03 Aug 2026 03:52:11 +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 643D51476; Sun, 2 Aug 2026 20:52:02 -0700 (PDT) Received: from localhost (a079125.arm.com [10.164.21.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B27843F86F; Sun, 2 Aug 2026 20:52:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785729126; bh=MMvyCXZogY5GexaFnJZNjm1E8eW84bXx4Pe82k6Fhu0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cncpuTcYd1zhdHDbpXR+M48JeVJjbcQwqQJtN3m16OAM3/sYUVtu8hitSOD1ZfChq YLLRP/lYPDcOAfFhjiM35VwcFnTHoRxAqJaKggt+tDGGOdtP55CN3eGukND2rpcFX/ hyHKYlDsFImfqRAgVSWRn1uigQUVAZgc9Bv288hE= Date: Mon, 3 Aug 2026 09:22:02 +0530 From: Linu Cherian To: Will Deacon Cc: Catalin Marinas , Ryan Roberts , Kevin Brodsky , Anshuman Khandual , Suzuki K Poulose , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Gavin Shan Subject: Re: [PATCH v4 6/6] arm64: cpufeature: Detect BBML3 based on ID_AA64MMFR2_EL1.BBM Message-ID: References: <20260723044034.2983651-1-linu.cherian@arm.com> <20260723044034.2983651-7-linu.cherian@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260802_205210_375428_7CE45441 X-CRM114-Status: GOOD ( 21.44 ) 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 Will, On Fri, Jul 31, 2026 at 04:13:20PM +0100, Will Deacon wrote: > On Thu, Jul 23, 2026 at 10:10:33AM +0530, Linu Cherian wrote: > > Add ID_AA64MMFR2_EL1.BBM based BBML3 feature detection in > > cpu_supports_bbml3() so that cpus with the feature would > > not have to be added into MIDR based supports_bbml3_list. > > > > Reviewed-by: Gavin Shan > > Reviewed-by: Anshuman Khandual > > Signed-off-by: Linu Cherian > > --- > > arch/arm64/kernel/cpufeature.c | 17 +++++++++-------- > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > > index 896bafdb00b1..dbd7d187520c 100644 > > --- a/arch/arm64/kernel/cpufeature.c > > +++ b/arch/arm64/kernel/cpufeature.c > > @@ -2133,6 +2133,12 @@ static bool hvhe_possible(const struct arm64_cpu_capabilities *entry, > > > > bool cpu_supports_bbml3(void) > > { > > + u64 mmfr2; > > + > > + mmfr2 = __read_sysreg_by_encoding(SYS_ID_AA64MMFR2_EL1); > > + if (SYS_FIELD_GET(ID_AA64MMFR2_EL1, BBM, mmfr2) >= ID_AA64MMFR2_EL1_BBM_3) > > + return true; > > This is a bit of a nit, but I think it would be more consistent to use > has_cpuid_feature() here instead of __read_sysreg_by_encoding(), similarly > to how we handle kpti in unmap_kernel_at_el0() (which also has both an > ID register field and a list of MIDRs). force_pte_mapping required by map_mem(during early boot) needs cpu_supports_bbml3 check and cpu features/capabilities are not initialized by that time. Should i add a comment there to clarify this ? Thanks, Linu Cherian.