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,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 48674C636C9 for ; Tue, 20 Jul 2021 13:32:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 282F060FF3 for ; Tue, 20 Jul 2021 13:32:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238610AbhGTMvD (ORCPT ); Tue, 20 Jul 2021 08:51:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:52714 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238700AbhGTMfU (ORCPT ); Tue, 20 Jul 2021 08:35:20 -0400 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 EFFE4610D2; Tue, 20 Jul 2021 13:15:58 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.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 1m5pbI-00EVqR-FY; Tue, 20 Jul 2021 14:15:57 +0100 Date: Tue, 20 Jul 2021 14:15:56 +0100 Message-ID: <87wnpl86sz.wl-maz@kernel.org> From: Marc Zyngier To: Quentin Perret Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, dbrazdil@google.com, Srivatsa Vaddagiri , Shanker R Donthineni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 04/16] KVM: arm64: Add MMIO checking infrastructure In-Reply-To: References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-5-maz@kernel.org> 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") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: qperret@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, dbrazdil@google.com, vatsa@codeaurora.org, sdonthineni@nvidia.com, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 Jul 2021 12:13:20 +0100, Quentin Perret wrote: > > On Thursday 15 Jul 2021 at 17:31:47 (+0100), Marc Zyngier wrote: > > +struct s2_walk_data { > > + kvm_pte_t pteval; > > + u32 level; > > +}; > > + > > +static int s2_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep, > > + enum kvm_pgtable_walk_flags flag, void * const arg) > > +{ > > + struct s2_walk_data *data = arg; > > + > > + data->level = level; > > + data->pteval = *ptep; > > + return 0; > > +} > > + > > +/* Assumes mmu_lock taken */ > > +static bool __check_ioguard_page(struct kvm_vcpu *vcpu, gpa_t ipa) > > +{ > > + struct s2_walk_data data; > > + struct kvm_pgtable_walker walker = { > > + .cb = s2_walker, > > + .flags = KVM_PGTABLE_WALK_LEAF, > > + .arg = &data, > > + }; > > + > > + kvm_pgtable_walk(vcpu->arch.hw_mmu->pgt, ALIGN_DOWN(ipa, PAGE_SIZE), > > + PAGE_SIZE, &walker); > > + > > + /* Must be a PAGE_SIZE mapping with our annotation */ > > + return (BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(data.level)) == PAGE_SIZE && > > + data.pteval == MMIO_NOTE); > > Nit: you could do this check in the walker directly and check the return > value of kvm_pgtable_walk() instead. That would allow to get rid of > struct s2_walk_data. > > Also, though the compiler might be able to optimize, maybe simplify the > level check to level == (KVM_PGTABLE_MAX_LEVELS - 1)? Yup, all good points. I guess I could do the same in my other series that parses the userspace PT to extract the level. Thanks, M. -- Without deviation from the norm, progress is not possible.