The extended control registers were not being updated in the KVM thread
context nor updated in the KVM state. This was causing issues when
checkpointing since the XCR0 value was reverting to the default value
rather than what it was previously before the checkpoint. THis was
causing multiple applications to crash due to executing instructions
which are now illegal instructions due to XCR0 being incorrect.
This commit adds the XCR0 as a misc register similar to the exiting x86
control registers and adds all of the helper functions to access and set
the register value. It also adds support for updating the KVM CPU's
state with the register value and updating the thread context's misc reg
value so that it is checkpointed along with the other misc regs.
Note that this does *not* add support for XSAVE of the AVX state (i.e.,
the upper 128 bits of YMM registers). It does however fix the immediate
problem in issue #958 .
Change-Id: I97456c8b57cbc7b381bd4be94944ce6567a43c76
6ed446e546