摘要:
A data processing apparatus, and method of managing at least one cache within such an apparatus, are provided. The data processing apparatus has at least one processing unit for executing a sequence of instructions, with each such processing unit having a cache associated therewith, each cache having a plurality of cache lines for storing data values for access by the associated processing unit when executing the sequence of instructions. Identification logic is provided which, for each cache, monitors data traffic within the data processing apparatus and based thereon generates a preferred for eviction identification identifying one or more of the data values as preferred for eviction. Cache maintenance logic is then arranged, for each cache, to implement a cache maintenance operation during which selection of one or more data values for eviction from that cache is performed having regard to any preferred for eviction identification generated by the identification logic for data values stored in that cache. It has been found that such an approach provides a very flexible technique for seeking to improve cache storage utilisation.
摘要:
A data processing apparatus and method are provided for controlling access to secure memory by virtual machines executing on processing circuitry. The processing circuitry executes hypervisor software to support the execution of multiple virtual machines on the processing circuitry. A memory system is provided for storing data for access by the processing circuitry, the memory system comprising secure memory for storing secure data and non-secure memory for storing non-secure data, the secure memory only being accessible via a secure access request. Address translation circuitry is responsive to an access request issued by a current virtual machine specifying a virtual address, to perform an address translation process to identify a physical address in the memory, and to cause a modified access request to be issued to the memory system specifying the physical address. A trusted virtual machine identifier is maintained and managed by the hypervisor software, with the hypervisor software setting the trusted virtual machine identifier if the current virtual machine is to be trusted to access the secure memory. Accordingly, in response to the access request issued by the current virtual machine, the address translation circuitry is only able to cause the modified access request to be issued as a secure access request specifying a physical address within the secure memory if the trusted virtual machine identifier is set. By such an approach, the hypervisor software is able to support multiple virtual machines at least some of which have access to secure memory under conditions controlled by the hypervisor software.
摘要:
An interrupt controller 2 is provided with priority registers 6 storing priority values P0-P9 used to determine prioritisation between received interrupt signals I0-I9. A priority value accessing circuit 10 provides multiple mappings to the priority values stored in dependence upon the priority value manager 16, 18, seeking to make an access. In this way, a first priority value manager 18, such as a secure operating system, can be given exclusive access to the highest priority values whilst a second priority value manager 16, such as a non-secure operating system, can be given access to a range of priority values as stored which are of a lower priority and yet as written or read by the non-secure operating system appear to the non-secure operating system to have a different, such as higher, priority level.
摘要:
Processing circuitry executes hypervisor software to support the execution of multiple virtual machines on the processing circuitry. A memory system stores data for access by the processing circuitry and includes secure memory and non-secure memory . The secure memory is only accessible via a secure access request. Address translation circuitry is responsive to an access request issued by a current virtual machine specifying a virtual address, to perform an address translation process to identify a physical address in the memory, and to cause a modified access request to be issued to the memory system specifying the physical address. The hypervisor software sets a trusted virtual machine identifier if the current virtual machine is to be trusted to access the secure memory. The address translation circuitry can only cause the modified access request to be issued as a secure access request to the secure memory if the trusted identifier is set.
摘要:
A data processing apparatus, and method of managing at least one cache within such an apparatus, are provided. The data processing apparatus has at least one processing unit for executing a sequence of instructions, with each such processing unit having a cache associated therewith, each cache having a plurality of cache lines for storing data values for access by the associated processing unit when executing the sequence of instructions. Identification logic is provided which, for each cache, monitors data traffic within the data processing apparatus and based thereon generates a preferred for eviction identification identifying one or more of the data values as preferred for eviction. Cache maintenance logic is then arranged, for each cache, to implement a cache maintenance operation during which selection of one or more data values for eviction from that cache is performed having regard to any preferred for eviction identification generated by the identification logic for data values stored in that cache. It has been found that such an approach provides a very flexible technique for seeking to improve cache storage utilisation.
摘要:
A data processing apparatus is provided comprising processing logic for issuing access requests when access to data is required, with each access request specifying a memory address associated with the data the subject of the access request. Access control logic is used to perform an access control operation to check for each access request whether the specified memory address is accessible by the processing logic. Further, a table is provided having a plurality of entries, each entry identifying an address range and an associated action. On occurrence of one or more predetermined events, the access control logic references the table to determine whether the specified address is within the address range identified by an entry of the table. If so, the associated action specified in that entry is invoked, whereas otherwise the access control logic causes any action indicated by the access control operation to be performed. This provides a particularly efficient mechanism for handling access requests in a variety of situations, for example within a virtualization environment where the access requests are directed to virtual devices implemented by hypervisor software.
摘要:
A data processing apparatus is provided comprising processing logic for issuing access requests when access to data is required, with each access request specifying a memory address associated with the data the subject of the access request. Access control logic is used to perform an access control operation to check for each access request whether the specified memory address is accessible by the processing logic. Further, a table is provided having a plurality of entries, each entry identifying an address range and an associated action. On occurrence of one or more predetermined events, the access control logic references the table to determine whether the specified address is within the address range identified by an entry of the table. If so, the associated action specified in that entry is invoked, whereas otherwise the access control logic causes any action indicated by the access control operation to be performed. This provides a particularly efficient mechanism for handling access requests in a variety of situations, for example within a virtualisation environment where the access requests are directed to virtual devices implemented by hypervisor software.
摘要:
An interrupt controller 2 is provided with priority registers 6 storing priority values P0-P9 used to determine prioritisation between received interrupt signals I0-I9. A priority value accessing circuit 10 provides multiple mappings to the priority values stored in dependence upon the priority value manager 16, 18, seeking to make an access. In this way, a first priority value manager 18, such as a secure operating system, can be given exclusive access to the highest priority values whilst a second priority value manager 16, such as a non-secure operating system, can be given access to a range of priority values as stored which are of a lower priority and yet as written or read by the non-secure operating system appear to the non-secure operating system to have a different, such as higher, priority level.
摘要:
The data processing apparatus has processing logic for performing data processing operations and a register bank for storing data associated with the processing logic. The register bank has at least one register group, each register group having a plurality of register sets. The processing logic has an operating state associated with each register group defining how that register group is used, a first operating state being a state in which each register set in the register group is used to support an independent execution thread of the processing logic, and a second operating state being a state in which the register sets of the register group are collectively used to support a single execution thread of the processing logic. Control logic is provided to control how the register sets of each register group are used dependent on the operating state associated with that register group.
摘要:
A multithreaded processor is provided with a saturating counter which serves to generate a thread preference signal to steer selection of which program thread operations are taken from for issue into the multiple processor pipelines. The counter is updated based upon the selections made for issue. The counter is a saturating counter and its sign bit may be used as a thread preference signal when discriminating between two threads. The update made to the count value can be weighted depending upon programmable priorities associated with the respective threads as well as a weighting based upon the time taken to execute the type of operation selected.