26-26 Vol. 3C
VM ENTRIES
•
The machine-check event is handled as if it occurred before the VM entry:
— If CR4.MCE = 0, operation of the logical processor depends on whether the logical processor is in SMX
operation:
1
•
If the logical processor is in SMX operation, an Intel
®
TXT shutdown condition occurs. The error code
used is 000CH, indicating “unrecoverable machine-check condition.”
•
If the logical processor is outside SMX operation, it goes to the shutdown state.
— If CR4.MCE = 1, a machine-check exception (#MC) is delivered through the IDT.
•
The machine-check event is handled after VM entry completes:
— If the VM entry ends with CR4.MCE = 0, operation of the logical processor depends on whether the logical
processor is in SMX operation:
•
If the logical processor is in SMX operation, an Intel
®
TXT shutdown condition occurs with error code
000CH (unrecoverable machine-check condition).
•
If the logical processor is outside SMX operation, it goes to the shutdown state.
— If the VM entry ends with CR4.MCE = 1, a machine-check exception (#MC) is generated:
•
If bit 18 (#MC) of the exception bitmap is 0, the exception is delivered through the guest IDT.
•
If bit 18 of the exception bitmap is 1, the exception causes a VM exit.
•
A VM-entry failure occurs as described in Section 26.7. The basic exit reason is 41, for “VM-entry failure due to
machine-check event.”
The first option is not used if the machine-check event occurs after any guest state has been loaded. The second
option is used only if VM entry is able to load all guest state.
1. A logical processor is in SMX operation if GETSEC[SEXIT] has not been executed since the last execution of GETSEC[SENTER]. A logi-
cal processor is outside SMX operation if GETSEC[SENTER] has not been executed or if GETSEC[SEXIT] was executed after the last
execution of GETSEC[SENTER]. See Chapter 6, “Safer Mode Extensions Reference,” in Intel® 64 and IA-32 Architectures Software