Official Last updated: 14 Jan 2026
Preface: Smartphones using the ARM Cortex-X925 CPU core are primarily powered by the MediaTek Dimensity 9400 and Dimensity 9400+ chipsets. Key flagship devices featuring this processor include the OPPO Find X8 Pro, vivo X200 series, and Xiaomi 15T Pro. These phones utilize the chip’s “all-big-core” design for high-performance computing.
Dimensity 9400 and Dimensity 9400+ both chipsets use the same core components, including the ARM Cortex-X925 CPU, the Immortalis-G925 GPU, and the NPU 890. The primary difference lies in the clock speeds and certain enhanced connectivity/AI features of the Plus model.
Background: Cache prefetch predictionrestriction by context – This instruction prevents cache allocation predictions that predict execution addresses based on information gathered from earlier execution within a particular execution context. The actions of code in the target execution context or contexts appearing in program order before the instruction cannot exploitatively control cache prefetch predictions occurring after the instruction is complete and synchronized.
The Cortex-X925 supports Armv9’s Realm Management Extension (RME), which goes a step further than traditional TEE:
Confidential Computing: In addition to Android (Normal World) and TEE (Secure World), Armv9 introduces Realm World.
Realm Guest OS: A fully encrypted Guest OS (called Realm) can run on the Hypervisor (EL2), which even the Android Kernel cannot peek at.
Vulnerability details: An issue has been identified in some Arm-based CPUs which may allow a modified, untrusted guest OS to compromise the host in certain hypervisor environments.
Workaround: To workaround this issue, affected partners must perform TLB invalidation whenever a CPP RCTX instruction is executed. For details on how to do this, please see the Errata Notice for the relevant product.
Official announcement: Please refer to the link for details –