From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Fedin Subject: RE: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi Date: Mon, 06 Jul 2015 09:42:43 +0300 Message-ID: <00fd01d0b7b6$f6cf3550$e46d9ff0$@samsung.com> References: <1435592237-17924-1-git-send-email-eric.auger@linaro.org> <1435592237-17924-2-git-send-email-eric.auger@linaro.org> <011f01d0b498$6a17aeb0$3e470c10$@samsung.com> <5596503E.6040902@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 17F8B57B24 for ; Mon, 6 Jul 2015 02:31:23 -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 Fe9K82vNT5qL for ; Mon, 6 Jul 2015 02:31:21 -0400 (EDT) Received: from mailout4.w1.samsung.com (mailout4.w1.samsung.com [210.118.77.14]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 3421757B05 for ; Mon, 6 Jul 2015 02:31:20 -0400 (EDT) Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NR100KYCZZ8HR40@mailout4.w1.samsung.com> for kvmarm@lists.cs.columbia.edu; Mon, 06 Jul 2015 07:42:44 +0100 (BST) In-reply-to: <5596503E.6040902@arm.com> Content-language: ru 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: 'Andre Przywara' , 'Eric Auger' , eric.auger@st.com, linux-arm-kernel@lists.infradead.org, 'Marc Zyngier' , christoffer.dall@linaro.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: pbonzini@redhat.com, linux-kernel@vger.kernel.org List-Id: kvmarm@lists.cs.columbia.edu Hello! > I like this approach, but it runs into problems: > As you read above the current documentation says that the flags field > must be zero and the current KVM_SET_GSI_ROUTING handler bails out if it > isn't. So userland would need to know whether it's safe to set that > field. This problem does not exist because: a) Older platforms do not need this flag, so they expect to get zero. b) ARM64 + GICv3 platform cannot work without this flag. This is perfectly OK combination IMO. Userland just knows, whether it needs to supply device ID or not. For example, my modified qemu now has kvm_msi_flags global variable which defaults to 0. ITS code, then, if activated, changes it to KVM_MSI_VALID_DEVID, and qemu starts supplying device IDs to the related calls. Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia