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Thu, 07 Aug 2025 06:57:19 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHXYwZoGNhakMxRJpYivC+7uq1cW0gVwDnE4VKL/NXOOs4ZMWf4zIuaDjvfzTtVOw3TIhYo9A== X-Received: by 2002:adf:fac6:0:b0:3b8:ff39:486d with SMTP id ffacd0b85a97d-3b8ff394bb9mr931369f8f.8.1754575039368; Thu, 07 Aug 2025 06:57:19 -0700 (PDT) Received: from [192.168.10.48] ([151.49.253.173]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-458bd5a0f9bsm127902595e9.0.2025.08.07.06.57.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 Aug 2025 06:57:18 -0700 (PDT) Message-ID: Date: Thu, 7 Aug 2025 15:57:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 16/26] memory: Make flatview_do_translate() return a pointer to MemoryRegionSection To: Zhao Liu , Peter Xu , David Hildenbrand , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Manos Pitsidianakis , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Thomas Huth , Junjie Mao Cc: qemu-devel@nongnu.org, qemu-rust@nongnu.org, Dapeng Mi , Chuanxiao Dong References: <20250807123027.2910950-1-zhao1.liu@intel.com> <20250807123027.2910950-17-zhao1.liu@intel.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-rust@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: QEMU Rust-related patches and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-rust-bounces+qemu-rust=archiver.kernel.org@nongnu.org Sender: qemu-rust-bounces+qemu-rust=archiver.kernel.org@nongnu.org On 8/7/25 14:30, Zhao Liu wrote: > Rust side will use cell::Opaque<> to hide details of C structure, and > this could help avoid the direct operation on C memory from Rust side. > > Therefore, it's necessary to wrap a translation binding and make it only > return the pointer to MemoryRegionSection, instead of the copy. > > As the first step, make flatview_do_translate return a pointer to > MemoryRegionSection, so that we can build a wrapper based on it. Independent of Rust, doing the copy as late as possible is good, but make it return a "const MemoryRegionSection*" so that there's no risk of overwriting data. Hopefully this does not show a bigger problem! Paolo > In addtion, add a global variable `unassigned_section` to help get a > pointer to an invalid MemoryRegionSection.