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[35.195.168.105]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43aba58713bsm186635635e9.34.2025.03.03.01.03.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Mar 2025 01:03:13 -0800 (PST) Date: Mon, 3 Mar 2025 09:03:09 +0000 From: Vincent Donnefort To: Quentin Perret Cc: maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 2/9] KVM: arm64: Add a range to __pkvm_host_share_guest() Message-ID: References: <20250228102530.1229089-1-vdonnefort@google.com> <20250228102530.1229089-3-vdonnefort@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Feb 28, 2025 at 07:06:46PM +0000, Quentin Perret wrote: > On Friday 28 Feb 2025 at 10:25:18 (+0000), Vincent Donnefort wrote: > > +int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu, > > enum kvm_pgtable_prot prot) > > { > > struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu); > > u64 phys = hyp_pfn_to_phys(pfn); > > u64 ipa = hyp_pfn_to_phys(gfn); > > struct hyp_page *page; > > + u64 size; > > int ret; > > > > if (prot & ~KVM_PGTABLE_PROT_RWX) > > return -EINVAL; > > > > - ret = check_range_allowed_memory(phys, phys + PAGE_SIZE); > > I'm not sure it is safe to drop this check here, see below. > > > + ret = __guest_check_transition_size(phys, ipa, nr_pages, &size); > > if (ret) > > return ret; > > > > host_lock_component(); > > guest_lock_component(vm); > > > > - ret = __guest_check_page_state_range(vcpu, ipa, PAGE_SIZE, PKVM_NOPAGE); > > + ret = __guest_check_page_state_range(vm, ipa, size, PKVM_NOPAGE); > > if (ret) > > goto unlock; > > > > page = hyp_phys_to_page(phys); > > Phys really needs to be a valid memory address here for 'page' to be > present in the vmemma -- dereference right below. So we can't rely on > the check in __host_check_page_state_range() sadly ... Haaa you're right. Sad to have this double check. Perhaps I won't use __host_check_page_state_range() then. > > > + ret = __host_check_page_state_range(phys, size, page->host_state); > > + if (ret) > > + goto unlock; > > + [...]