Re: [PATCH 20/27] nVMX: Deciding if L0 or L1 should handle an L2 exit

[Avi Kivity <avi@redhat.com>]

  On 10/20/2010 02:13 PM, Avi Kivity wrote:
>> +    switch (exit_reason) {
>> +    case EXIT_REASON_EXTERNAL_INTERRUPT:
>> +        return 0;
>> +    case EXIT_REASON_EXCEPTION_NMI:
>> +        if (!is_exception(intr_info))
>> +            return 0;
>> +        else if (is_page_fault(intr_info)&&  (!enable_ept))
>> +            return 0;
> +
>
> We may still find out later that the page fault needs to be 
> intercepted by the guest, yes?
>
>> +        return (vmcs12->exception_bitmap&
>> +                (1u<<  (intr_info&  INTR_INFO_VECTOR_MASK)));
>> +    case EXIT_REASON_EPT_VIOLATION:
>> +        return 0;
>> +    case EXIT_REASON_INVLPG:
>> +        return (vmcs12->cpu_based_vm_exec_control&
>> +                CPU_BASED_INVLPG_EXITING);
>> +    case EXIT_REASON_MSR_READ:
>> +    case EXIT_REASON_MSR_WRITE:
>> +        return nested_vmx_exit_handled_msr(vcpu, vmcs12, exit_reason);
>> +    case EXIT_REASON_CR_ACCESS:
>> +        return nested_vmx_exit_handled_cr(vcpu, vmcs12);
>> +    case EXIT_REASON_DR_ACCESS:
>> +        return (vmcs12->cpu_based_vm_exec_control&
>> +                CPU_BASED_MOV_DR_EXITING);
>> +    default:
>> +        /*
>> +         * One particularly interesting case that is covered here is an
>> +         * exit caused by L2 running a VMX instruction. L2 is guest
>> +         * mode in L1's world, and according to the VMX spec running a
>> +         * VMX instruction in guest mode should cause an exit to root
>> +         * mode, i.e., to L1. This is why we need to return r=1 for
>> +         * those exit reasons too. This enables further nesting: Like
>> +         * L0 emulates VMX for L1, we now allow L1 to emulate VMX for
>> +         * L2, who will then be able to run L3.
>> +         */
>> +        return 1;
>
> What about intr/nmi window?
>

Also WBINVD, pause loop exit, rdtsc[p], monitor/mwait, hlt.

It's best to list every exit reason here, so it's easier to review and 
maintain.


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.