From patchwork Thu Jun 3 18:33:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 12297821 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 337ABC47082 for ; Thu, 3 Jun 2021 18:36:50 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 020DB613D7 for ; Thu, 3 Jun 2021 18:36:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 020DB613D7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Y5ZAkqsTlNxyBY4PeX+eHp14XjuxkrOccSn3ZexoXx8=; b=QOk9am0jl+Jtc8 QKw4nVrw6j/VTDxmj8Fm6uHfHKcTT6AC2aCTe86sx2DYJHlbv3y5lSiOaFHl/AeYflDj1kmnRgKfj jyL25rgyYkT8ZJOYCXv03+YTvjXO1dT3dY4Omi5KQbGHt+WIiF7ElagjPZ/FGVUrlvOfY2J2J48hP hkj9Xv6RHWsz1ilrxTjuR2JJxh1QijwNYq54q/Vsk6oWNS32Oa9lhUiZYqPYKxAYle2C7O0muDIcM EwXdiW5r0ZCD/lZ6+rg26dvdZOV1nLv4zQZpm9jecnqP/FCB/yvhclmK/kysFjogDBqlvcygjuE+j 2XkJeCaNS+BGFRfyjM4A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1losAg-00ACJ6-L8; Thu, 03 Jun 2021 18:34:22 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1losAN-00ACGs-7Y for linux-arm-kernel@lists.infradead.org; Thu, 03 Jun 2021 18:34:04 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7F2C8613B8; Thu, 3 Jun 2021 18:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622745242; bh=osyrOd8rLcVCMiPHAeJKLzTGdMUBbbPPNLLfrYOVNtE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fOt+VKmNu2qb7NlmlC8F8f7NZks31mqaTKoFAcQTxTnnIZsP99bm4KVUW3Fy5BRvN k2jFjdJeC1Ex6aXIlzQTS6Z+2nmuqbXQ5BCBEDUFJ2hXtvBa2kF4PGG8m6Ug2xCo0Q 2mkPnUbq1g9fcBSTNR1e0d8gzL2CvA8qU1mdCLwmONsEdMYiX9MBJPQUtdKpSzTkEr ei3Ud1mbQSStGuUhg7+ec20zSiVnEUYt0Fyd7Ylz0JXyoDEzLq6C2N7S8fN7v4J9dy l0CBMMnNmYEK9oOkkz2xWN2Ub6RyqV+ey0y9/m+fBqIL12YAOOv7nPK2CygTSFZayc TwB4LD/lrL5yg== From: Will Deacon To: kvmarm@lists.cs.columbia.edu Cc: Will Deacon , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Mark Rutland , Christoffer Dall , Paolo Bonzini , Fuad Tabba , Quentin Perret , Sean Christopherson , David Brazdil , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/4] KVM: arm64: Extend comment in has_vhe() Date: Thu, 3 Jun 2021 19:33:45 +0100 Message-Id: <20210603183347.1695-3-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210603183347.1695-1-will@kernel.org> References: <20210603183347.1695-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210603_113403_337588_E515673F X-CRM114-Status: GOOD ( 11.33 ) 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 has_vhe() expands to a compile-time constant when evaluated from the VHE or nVHE code, alternatively checking a static key when called from elsewhere in the kernel. On face value, this looks like a case of premature optimization, but in fact this allows symbol references on VHE-specific code paths to be dropped from the nVHE object. Expand the comment in has_vhe() to make this clearer, hopefully discouraging anybody from simplifying the code. Cc: David Brazdil Signed-off-by: Will Deacon Acked-by: Mark Rutland --- arch/arm64/include/asm/virt.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 7379f35ae2c6..3218ca17f819 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -111,6 +111,9 @@ static __always_inline bool has_vhe(void) /* * Code only run in VHE/NVHE hyp context can assume VHE is present or * absent. Otherwise fall back to caps. + * This allows the compiler to discard VHE-specific code from the + * nVHE object, reducing the number of external symbol references + * needed to link. */ if (is_vhe_hyp_code()) return true;