Apparatus and method for managing unsupported instruction set architecture (ISA) features in a virtualized environment

A method comprising:

• executing instructions on at least one core of a plurality of cores, each having a current microarchitecture including hardware support for virtual execution environment comprising a hypervisor running at a first privilege level and one or more virtual machines each running at a second privilege level, the microarchitecture further including partial hardware support for executing deprecated instructions associated with a prior microarchitecture;
• performing either a first type or a second type of virtual machine exit responsive to detecting a deprecated instruction in a first virtual machine,
• performing by the hypervisor, responsive to the first type of virtual machine exit, a first emulation of the prior microarchitecture without reliance on the partial hardware support, and
• performing by the hypervisor, responsive to the first type of virtual machine exit, a second emulation of the prior microarchitecture relying on the partial hardware support.

A non-transitory machine-readable medium having program code stored thereon which, when executed by a machine, causes the machine to perform the operations of:

• executing instructions on at least one core of a plurality of cores, each having a current microarchitecture including hardware support for virtual execution environment comprising a hypervisor running at a first privilege level and one or more virtual machines each running at a second privilege level, the microarchitecture further including partial hardware support for executing deprecated instructions associated with a prior microarchitecture;
• performing either a first type or a second type of virtual machine exit responsive to detecting a deprecated instruction in a first virtual machine,
• performing by the hypervisor, responsive to the first type of virtual machine exit, a first emulation of the prior microarchitecture without reliance on the partial hardware support, and
• performing by the hypervisor, responsive to the first type of virtual machine exit, a second emulation of the prior microarchitecture relying on the partial hardware support.