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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 DC7EAC433DF for ; Tue, 14 Jul 2020 11:34:22 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 573F622208 for ; Tue, 14 Jul 2020 11:34:22 +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="uSOPndyO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 573F622208 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 DA67B4B195; Tue, 14 Jul 2020 07:34:21 -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 8OFdIrV+9iDy; Tue, 14 Jul 2020 07:34:20 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CB9394B197; Tue, 14 Jul 2020 07:34:20 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A77214B186 for ; Tue, 14 Jul 2020 07:34:19 -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 iu0zKuQUjN7N for ; Tue, 14 Jul 2020 07:34:18 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id A8EA64B145 for ; Tue, 14 Jul 2020 07:34:18 -0400 (EDT) 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 57BCB22203; Tue, 14 Jul 2020 11:34:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594726457; bh=kmxoxxCKYn4praQ9Nl67zZ5JOsPadeFdzaauOFi7Zbs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uSOPndyObFfsQ/SmCaA+ixqJQHNA7lCVJvrPYIMKkTDCCRtsXDSN3Vb4r6+1VTgjo hC+C1ds1Rl0SX/mSSXNJ5R6n4hL6C58D4suvjQ9lqeZi4GhNWkimsaIMYc/HnFrmeV +HslyEP9H2h2VLi5lbvbZDz4Xlsv5nFJBTavdeSE= 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 1jvJCR-00BeTe-V3; Tue, 14 Jul 2020 12:34:16 +0100 MIME-Version: 1.0 Date: Tue, 14 Jul 2020 12:34:15 +0100 From: Marc Zyngier To: zhukeqian Subject: Re: [Question] About scaling factor of Enhanced Counter Virtualization In-Reply-To: References: User-Agent: Roundcube Webmail/1.4.5 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: zhukeqian1@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, catalin.marinas@arm.com, will@kernel.org, suzuki.poulose@arm.com, yebiaoxiang@huawei.com, xiexiangyou@huawei.com, wanghaibin.wang@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: Catalin Marinas , yebiaoxiang@huawei.com, Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.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 Keqian, On 2020-07-14 03:20, zhukeqian wrote: > Hi all, > > We are studying Enhanced Counter Virtualization (introduced by ARMv8.6 > extension), and here is a question > raised by Biaoxiang Ye : > > Described in the ARMv8.6 Extension Specification: > Note: the scaling factor CNTSCALE is designed as a 2.62 bit fixed > point number, so permitting a scaling up by > (nearly) a factor 4. The scaling factor CNTISCALE is signed as an 8.56 > number for the scaling of the values > written into the timers for comparison with the actual count. This > implies that the greatest scaling down of the > counter supported in (nearly) a factor of *512*. > > We think the number "512" should be "256" (2^8), or do we miss > something? This register doesn't seem to be described in ARM DDI 0487F.b, which is the official documentation and does contain the ARMv8.6 material, including ARMv8.6-ECV. Either you are looking at confidential information (and nobody can answer you in public), or obsolete information (and nobody knows what this is about). In any case, this is most probably a question for ARM's support team, and not the kernel mailing lists. 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 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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 6F51BC433DF for ; Tue, 14 Jul 2020 11:35:38 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 3A0682082E for ; Tue, 14 Jul 2020 11:35:38 +0000 (UTC) Authentication-Results: mail.kernel.org; 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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594726457; bh=kmxoxxCKYn4praQ9Nl67zZ5JOsPadeFdzaauOFi7Zbs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uSOPndyObFfsQ/SmCaA+ixqJQHNA7lCVJvrPYIMKkTDCCRtsXDSN3Vb4r6+1VTgjo hC+C1ds1Rl0SX/mSSXNJ5R6n4hL6C58D4suvjQ9lqeZi4GhNWkimsaIMYc/HnFrmeV +HslyEP9H2h2VLi5lbvbZDz4Xlsv5nFJBTavdeSE= 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 1jvJCR-00BeTe-V3; Tue, 14 Jul 2020 12:34:16 +0100 MIME-Version: 1.0 Date: Tue, 14 Jul 2020 12:34:15 +0100 From: Marc Zyngier To: zhukeqian Subject: Re: [Question] About scaling factor of Enhanced Counter Virtualization In-Reply-To: References: User-Agent: Roundcube Webmail/1.4.5 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: zhukeqian1@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, catalin.marinas@arm.com, will@kernel.org, suzuki.poulose@arm.com, yebiaoxiang@huawei.com, xiexiangyou@huawei.com, wanghaibin.wang@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200714_073418_291224_502D6D76 X-CRM114-Status: GOOD ( 13.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Suzuki K, Poulose" , Catalin Marinas , xiexiangyou@huawei.com, yebiaoxiang@huawei.com, James Morse , wanghaibin.wang@huawei.com, Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Keqian, On 2020-07-14 03:20, zhukeqian wrote: > Hi all, > > We are studying Enhanced Counter Virtualization (introduced by ARMv8.6 > extension), and here is a question > raised by Biaoxiang Ye : > > Described in the ARMv8.6 Extension Specification: > Note: the scaling factor CNTSCALE is designed as a 2.62 bit fixed > point number, so permitting a scaling up by > (nearly) a factor 4. The scaling factor CNTISCALE is signed as an 8.56 > number for the scaling of the values > written into the timers for comparison with the actual count. This > implies that the greatest scaling down of the > counter supported in (nearly) a factor of *512*. > > We think the number "512" should be "256" (2^8), or do we miss > something? This register doesn't seem to be described in ARM DDI 0487F.b, which is the official documentation and does contain the ARMv8.6 material, including ARMv8.6-ECV. Either you are looking at confidential information (and nobody can answer you in public), or obsolete information (and nobody knows what this is about). In any case, this is most probably a question for ARM's support team, and not the kernel mailing lists. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel