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=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0C223C2D0DB for ; Mon, 20 Jan 2020 13:26:49 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 887B221835 for ; Mon, 20 Jan 2020 13:26:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="FwF+8LB/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 887B221835 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 26A5B4AEC9; Mon, 20 Jan 2020 08:26:48 -0500 (EST) 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 dRChxWrLoTd0; Mon, 20 Jan 2020 08:26:43 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8F20D4AF26; Mon, 20 Jan 2020 08:26:43 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C609B4AF24 for ; Mon, 20 Jan 2020 08:26:41 -0500 (EST) 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 yhBaqSFVHFF1 for ; Mon, 20 Jan 2020 08:26:35 -0500 (EST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id AAEEB4AEC9 for ; Mon, 20 Jan 2020 08:26:35 -0500 (EST) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6E5E521835; Mon, 20 Jan 2020 13:26:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579526794; bh=klYwhSlzXGsDXrYWVAaBb32aIuKy3FUULwLCrFi2k0c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=FwF+8LB/UCFSgtVn0ih4G4gqnqAVSZjaeZM8Jq/DOgl1pngNGCGMNDMHmbN+bcjoG jyDtt2PLwsQeXv3ysNL8YlYrjJsTVuoR6u4h8bvhUOEOjbjMAtgFDPAIeC3sH32+hp syxisp4DxaTeQ9fFXoP9L8bbkl7qf0+5QIjwN7Fc= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1itX4a-000HFR-O1; Mon, 20 Jan 2020 13:26:32 +0000 MIME-Version: 1.0 Date: Mon, 20 Jan 2020 13:26:32 +0000 From: Marc Zyngier To: Andrew Jones Subject: Re: [PATCH] arm64: KVM: Add XXX UAPI notes for swapped registers In-Reply-To: <20200120130825.28838-1-drjones@redhat.com> References: <20200120130825.28838-1-drjones@redhat.com> Message-ID: <99903fdb3e0d34cb7957981b484fc28c@kernel.org> X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.8 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: drjones@redhat.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Andrew, Many thanks for this. Comments below. On 2020-01-20 13:08, Andrew Jones wrote: > Two UAPI system register IDs do not derive their values from the > ARM system register encodings. This is because their values were > accidentally swapped. As the IDs are API, they cannot be changed. > Add XXX notes to point them out. > > Suggested-by: Marc Zyngier > Signed-off-by: Andrew Jones > --- > Documentation/virt/kvm/api.txt | 8 ++++++++ > arch/arm64/include/uapi/asm/kvm.h | 11 +++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.txt > b/Documentation/virt/kvm/api.txt > index ebb37b34dcfc..11556fc457c3 100644 > --- a/Documentation/virt/kvm/api.txt > +++ b/Documentation/virt/kvm/api.txt > @@ -2196,6 +2196,14 @@ arm64 CCSIDR registers are demultiplexed by > CSSELR value: > arm64 system registers have the following id bit patterns: > 0x6030 0000 0013 > > +XXX: Two system register IDs do not follow the specified pattern. > These > + are KVM_REG_ARM_TIMER_CVAL and KVM_REG_ARM_TIMER_CNT, which map > to > + system registers CNTV_CVAL_EL0 and CNTVCT_EL0 respectively. > These > + two had their values accidentally swapped, which means TIMER_CVAL > is > + derived from the register encoding for CNTVCT_EL0 and TIMER_CNT > is > + derived from the register encoding for CNTV_CVAL_EL0. As this is > + API, it must remain this way. Is 'XXX' an establiched way of documenting this kind of misfeature? I couldn't find any other occurrence in Documentation, but I haven't searched very hard. If nobody has a better idea, I'll queue it as is. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm