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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 85CF1C5DF7D for ; Tue, 18 Aug 2026 14:07:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6BABA6B018F; Tue, 18 Aug 2026 10:07:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 66BB46B0190; Tue, 18 Aug 2026 10:07:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5A77F6B0191; Tue, 18 Aug 2026 10:07:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 3C5806B018F for ; Tue, 18 Aug 2026 10:07:53 -0400 (EDT) Received: from smtpin10.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id C5C65C0202 for ; Tue, 18 Aug 2026 14:07:52 +0000 (UTC) X-FDA: 85114568784.10.23B4887 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf02.hostedemail.com (Postfix) with ESMTP id 1263C80003 for ; Tue, 18 Aug 2026 14:07:50 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=arm.com header.s=foss header.b=jlQrt93o; spf=pass (imf02.hostedemail.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787062071; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Ln7Mczd79sZi5QwsaLE9jqFE0MNCEuo9MspZyFqDHr0=; b=N9oFWbTHJDz60fc3IG+Pe7OfzS64Q++/702lA0apDEK5DjB9nUj2tHuXaCkdOx0f3i1wpg RoqMMPoEVvvbngd5kR28/Foj0fyVH2Gv1V94G638w4R9Dteg24ury6KFmNqSmUpmacODdD vT3G4EwUlnZogpRMeLiKj6t9k+256QM= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=arm.com header.s=foss header.b=jlQrt93o; spf=pass (imf02.hostedemail.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787062071; b=jMzycDAeLMCggUSYzLTgNja1tFKxsinssna0t+BAUc1wMc7pVEz/Zy+qCVKT2xG5/8+SXa 639uXf2CTwtXDI8KBV1wLxsrbkTHCfq9hWCJXp63KY0yZy4FuOdBAon2+whQBjsZeYYatM 8+vHGX11zGLppkWdPcnirsIf/KkPTO8= 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 44278152B; Tue, 18 Aug 2026 07:07:46 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 187C43F85F; Tue, 18 Aug 2026 07:07:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787062070; bh=XYnpofG5ApFYBdgBh7eiqhDJLh9ipL/B1jlA8wAAIas=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jlQrt93omVnNUGW5AJAWkmrhdAxdJUeYlENyL9uf3jbP9mEjIJbPbVHtQ8AbK/8XQ qBdKSDBteuuzyBA4Km/Yh2uL4pt+s6L1zOxsmN2ydh8aCItQsF1z7h81P3Gf7S8WvB wrjfJAgW8ba8u3QAJm4YaQLsE0ncWlqwcTgwpqOg= Date: Tue, 18 Aug 2026 15:07:45 +0100 From: Catalin Marinas To: James Houghton Cc: Will Deacon , Muchun Song , Oscar Salvador , Nikos Nikoleris , Linu Cherian , Mark Rutland , David Hildenbrand , Andrew Morton , Ryan Roberts , Nanyong Sun , Yu Zhao , Frank van der Linden , David Rientjes , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH 07/18] arm64: Add system_supports_hvo Message-ID: References: <20260708031129.3503195-1-jthoughton@google.com> <20260708031129.3503195-8-jthoughton@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260708031129.3503195-8-jthoughton@google.com> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1263C80003 X-Stat-Signature: bj4zua5xeamtfzay34gtebe5gpws6rc1 X-Rspam-User: X-HE-Tag: 1787062070-291858 X-HE-Meta: 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 txtGAMbD amW0OunpL8ZJVtBVvgx0sGvwQglUp+VmQxSx8vVpY7EkfvXBk7sEfYsxAuRZGW7wuPsXy4Z1fu4jAsHIT30MGRxaCs+ZQro9verZ+GvIGSmU6l5GgNtR1YuCLhOOaG6cA72Fly6NGVOrQ+inZJnJ/b4IouQlBSO6j9a0qRO97cCBAXdQQnBXdXpuaETheekZKSSaJsplnNWPCQlKE5uSZqG0ShYzlMkvyz4OUH3j97xEasd/4OY3O6l8FlmCbvrbUQi17c9l2taJkIdyV/7+/Ev75dA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 08, 2026 at 03:11:17AM +0000, James Houghton wrote: > diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h > index 25c61cda901c..6db3ef827f86 100644 > --- a/arch/arm64/include/asm/cpucaps.h > +++ b/arch/arm64/include/asm/cpucaps.h > @@ -75,6 +75,8 @@ cpucap_is_possible(const unsigned int cap) > return IS_ENABLED(CONFIG_HW_PERF_EVENTS); > case ARM64_HAS_LSUI: > return IS_ENABLED(CONFIG_ARM64_LSUI); > + case ARM64_HVO_COMPATIBLE: > + return IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP); > } We shouldn't use HVO, a software feature, as a CPU capability name, even if it's called HVO_COMPATIBLE. Maybe we can come up with a hardware related name, e.g. BBM_THROUGH_AF. > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 9a22df0c5120..3b9224b99a5f 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -2172,6 +2172,16 @@ static bool has_bbml2_noabort(const struct arm64_cpu_capabilities *caps, int sco > return cpu_supports_bbml2_noabort(); > } > > +static bool hvo_compatible(const struct arm64_cpu_capabilities *caps, int scope) > +{ > + /* > + * We need BBML2 to support Block -> Table transitions without taking > + * faults, and we need HW AF support to support changing the OA without > + * taking faults. > + */ > + return cpu_supports_bbml2_noabort() && supports_hw_af(scope); > +} I think this is wrong. cpu_supports_bbml2_noabort() only checks the current CPU while hvo_compatible() will be run once on the sanitised register values (SCOPE_SYSTEM). I should be something like: cpus_have_cap(ARM64_HAS_BBML2_NOABORT) && supports_hw_af(scope) -- Catalin