Main Processor

CXD5315GG
See Kermit.

Cortex A9 MPcore
The actual application processor cores are Cortex A9, which is common in modern high performance embedded devices like cell phones and tablets. The Technical Reference Manual gives a good overview of the specific processor features and is a good reference for what ARMv7 implementation specific features are enabled. The Vita cores have a MIDR value of, meaning it is Cortex A9 r2p10. Indeed there are usage of undocumented CP15 registers.

Another manual that's important is the MPCore Technical Reference Manual which is specific to the multi-core system the Vita uses. The main information of use are descriptors for the private memory region defined with the  signal. This is mapped to physical address.

Interrupt Controller
As part of the Cortex A9 MPcore, the Vita also implements the Generic Interrupt Controller Architecture. More information on interrupts can be found here.

PL310 L2 Cache
The Vita uses the PL310 r3p1-50rel0 L2 cache (Cache ID Register = 0x410000C7) is is mapped to.