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Tue, 20 Jul 2021 04:13:23 -0700 (PDT) Received: from google.com ([2a00:79e0:d:210:83e0:11ac:c870:2b97]) by smtp.gmail.com with ESMTPSA id y3sm23651964wrh.16.2021.07.20.04.13.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jul 2021 04:13:23 -0700 (PDT) Date: Tue, 20 Jul 2021 12:13:20 +0100 From: Quentin Perret To: Marc Zyngier Subject: Re: [PATCH 04/16] KVM: arm64: Add MMIO checking infrastructure Message-ID: References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-5-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210715163159.1480168-5-maz@kernel.org> Cc: kernel-team@android.com, kvm@vger.kernel.org, Srivatsa Vaddagiri , linux-kernel@vger.kernel.org, Shanker R Donthineni , will@kernel.org, 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 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)? Thanks, Quentin > +} _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm