From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v4 06/10] KVM: arm: vgic: Support 64-bit data manipulation on 32-bit host systems Date: Thu, 22 Sep 2016 11:00:07 +0100 Message-ID: <57E3ABA7.2060003@arm.com> References: <1473691764-29424-1-git-send-email-vladimir.murzin@arm.com> <1473691764-29424-7-git-send-email-vladimir.murzin@arm.com> 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 7018249B2E for ; Thu, 22 Sep 2016 05:51:03 -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 14K41m1+HT+P for ; Thu, 22 Sep 2016 05:51:02 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 580FD40F77 for ; Thu, 22 Sep 2016 05:51:02 -0400 (EDT) In-Reply-To: <1473691764-29424-7-git-send-email-vladimir.murzin@arm.com> 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: Vladimir Murzin , kvmarm@lists.cs.columbia.edu Cc: andre.przywara@arm.com, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On 12/09/16 15:49, Vladimir Murzin wrote: > We have couple of 64-bit registers defined in GICv3 architecture, so > unsigned long accesses to these registers will only access a single > 32-bit part of that regitser. On the other hand these registers can't > be accessed as 64-bit with a single instruction like ldrd/strd or > ldmia/stmia if we run a 32-bit host because KVM does not support > access to MMIO space done by these instructions. > > It means that a 32-bit guest accesses these registers in 32-bit > chunks, so the only thing we need to do is to ensure that > extract_bytes() always takes 64-bit data. > > Signed-off-by: Vladimir Murzin > --- > virt/kvm/arm/vgic/vgic-mmio-v3.c | 2 +- > virt/kvm/arm/vgic/vgic-mmio.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) Acked-by: Marc Zyngier M. -- Jazz is not dead. It just smells funny... From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Thu, 22 Sep 2016 11:00:07 +0100 Subject: [PATCH v4 06/10] KVM: arm: vgic: Support 64-bit data manipulation on 32-bit host systems In-Reply-To: <1473691764-29424-7-git-send-email-vladimir.murzin@arm.com> References: <1473691764-29424-1-git-send-email-vladimir.murzin@arm.com> <1473691764-29424-7-git-send-email-vladimir.murzin@arm.com> Message-ID: <57E3ABA7.2060003@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/09/16 15:49, Vladimir Murzin wrote: > We have couple of 64-bit registers defined in GICv3 architecture, so > unsigned long accesses to these registers will only access a single > 32-bit part of that regitser. On the other hand these registers can't > be accessed as 64-bit with a single instruction like ldrd/strd or > ldmia/stmia if we run a 32-bit host because KVM does not support > access to MMIO space done by these instructions. > > It means that a 32-bit guest accesses these registers in 32-bit > chunks, so the only thing we need to do is to ensure that > extract_bytes() always takes 64-bit data. > > Signed-off-by: Vladimir Murzin > --- > virt/kvm/arm/vgic/vgic-mmio-v3.c | 2 +- > virt/kvm/arm/vgic/vgic-mmio.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) Acked-by: Marc Zyngier M. -- Jazz is not dead. It just smells funny...