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 Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 238F0C433F5 for ; Sun, 21 Nov 2021 12:37:29 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id BA6CD4B1A9; Sun, 21 Nov 2021 07:37:28 -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 J+FHiIX5dJBE; Sun, 21 Nov 2021 07:37:26 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B2C694B187; Sun, 21 Nov 2021 07:37:26 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6A4E04B13A for ; Sun, 21 Nov 2021 07:37:25 -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 LJd-ix-MKb4d for ; Sun, 21 Nov 2021 07:37:24 -0500 (EST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 410794064F for ; Sun, 21 Nov 2021 07:37:24 -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 8429260555; Sun, 21 Nov 2021 12:37:23 +0000 (UTC) Received: from ip-185-104-136-29.ptr.icomera.net ([185.104.136.29] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mom5x-006sR9-Fi; Sun, 21 Nov 2021 12:37:21 +0000 Date: Sun, 21 Nov 2021 12:37:21 +0000 Message-ID: <87ilwlsn0e.wl-maz@kernel.org> From: Marc Zyngier To: Reiji Watanabe Subject: Re: [RFC PATCH v3 03/29] KVM: arm64: Introduce struct id_reg_info In-Reply-To: References: <20211117064359.2362060-1-reijiw@google.com> <20211117064359.2362060-4-reijiw@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.104.136.29 X-SA-Exim-Rcpt-To: reijiw@google.com, eauger@redhat.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, will@kernel.org, pshier@google.com, pbonzini@redhat.com, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kvm@vger.kernel.org, Peter Shier , Eric Auger , Paolo Bonzini , 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, 19 Nov 2021 04:47:53 +0000, Reiji Watanabe wrote: > > I am going to add the following comment. Does it look clear enough for you ? > > /* > * This is an optional ID register specific validation function. > * When userspace tries to set the ID register, arm64_check_features() > * will check if the requested value indicates any features that cannot > * be supported by KVM on the host. But, some ID register fields need > * a special checking and this function can be used for such fields. > * e.g. KVM_CREATE_DEVICE must be used to configure GICv3 for a guest. > * ID_AA64PFR0_EL1.GIC shouldn't be set to 1 unless GICv3 is configured. There is no such requirement. GICv3 has a compatibility interface, and although KVM doesn't make use of it, there is no reason not to expose that GICv3 exists on the CPU even if not using it. Even more, this has been the case forever, and making this change now would probably break migration. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm