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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 BB60BC47082 for ; Thu, 3 Jun 2021 18:34:08 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 46683613DC for ; Thu, 3 Jun 2021 18:34:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46683613DC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DD2E54B0AC; Thu, 3 Jun 2021 14:34:07 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id F8ezOVrULjzg; Thu, 3 Jun 2021 14:34:06 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C6E814B0E7; Thu, 3 Jun 2021 14:34:06 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 958224B10C for ; Thu, 3 Jun 2021 14:34:05 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id MgHG3nwfEitT for ; Thu, 3 Jun 2021 14:34:04 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id B817D4B108 for ; Thu, 3 Jun 2021 14:34:03 -0400 (EDT) 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 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 Cc: kvm@vger.kernel.org, Marc Zyngier , linux-arm-kernel@lists.infradead.org, Sean Christopherson , Paolo Bonzini , Will Deacon X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu 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 --- 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; -- 2.32.0.rc0.204.g9fa02ecfa5-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm