From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Murzin Subject: Re: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support Date: Tue, 6 Sep 2016 14:23:16 +0100 Message-ID: <57CEC344.7030706@arm.com> References: <1471344418-19568-1-git-send-email-vladimir.murzin@arm.com> <1471344418-19568-8-git-send-email-vladimir.murzin@arm.com> <20160905112927.GL26366@cbox> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4BEC149B51 for ; Tue, 6 Sep 2016 09:14:55 -0400 (EDT) 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 QysUcIlEfp63 for ; Tue, 6 Sep 2016 09:14:54 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9A9A049B50 for ; Tue, 6 Sep 2016 09:14:54 -0400 (EDT) In-Reply-To: <20160905112927.GL26366@cbox> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Christoffer Dall Cc: marc.zyngier@arm.com, andre.przywara@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu Sorry, missed this one On 05/09/16 12:29, Christoffer Dall wrote: >> >> > +static bool __hyp_text __has_useable_gicv3_cpuif(void) >> > +{ >> > + if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28)) > Do we have a define for bit 28 we could use? I'll check it. > > Does this actually work on all v7 boards? The v7 ARM ARM seems to state > that this bitfield is Reserved, UNK. Does that somehow mean 'is going > to be zero'? It is how v7ARM ARM I have defines UNK An abbreviation indicating that software must treat a field as containing an UNKNOWN value. Hardware must implement the bit as read as 0, or all 0s for a bit field. Software must not rely on the field reading as zero. It seems goes under 'is going to be zero' case, no? Cheers Vladimir From mboxrd@z Thu Jan 1 00:00:00 1970 From: vladimir.murzin@arm.com (Vladimir Murzin) Date: Tue, 6 Sep 2016 14:23:16 +0100 Subject: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support In-Reply-To: <20160905112927.GL26366@cbox> References: <1471344418-19568-1-git-send-email-vladimir.murzin@arm.com> <1471344418-19568-8-git-send-email-vladimir.murzin@arm.com> <20160905112927.GL26366@cbox> Message-ID: <57CEC344.7030706@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Sorry, missed this one On 05/09/16 12:29, Christoffer Dall wrote: >> >> > +static bool __hyp_text __has_useable_gicv3_cpuif(void) >> > +{ >> > + if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28)) > Do we have a define for bit 28 we could use? I'll check it. > > Does this actually work on all v7 boards? The v7 ARM ARM seems to state > that this bitfield is Reserved, UNK. Does that somehow mean 'is going > to be zero'? It is how v7ARM ARM I have defines UNK An abbreviation indicating that software must treat a field as containing an UNKNOWN value. Hardware must implement the bit as read as 0, or all 0s for a bit field. Software must not rely on the field reading as zero. It seems goes under 'is going to be zero' case, no? Cheers Vladimir