Hi,
Actually, I know that disabling EPT would work. But thank U anyway.
What I interesting in is why would it fail when EPT is enable.
Thank U for answering.
2012/10/9 Marcelo Tosatti <mtosatti@xxxxxxxxxx>:
> On Mon, Oct 08, 2012 at 04:15:57PM +0800, R wrote:
>> Hi,
>>
>> I am a student. And my teacher told me to monitor every process in guest.
>> So, I try to intercept every Cr3 access. However, if kvm is loaded
>> with EPT enable, Acesses to Cr3 would not cause VM-exit.
>
> Disable EPT by loading kvm-intel.ko module with enable_ept=0 parameter.
> Then, CR3 accesses will trap.
>
>> I modified the code to change vmcs configuration.
>> To be specific, these functions are rewirted.
>> static void ept_update_paging_mode_cr0(unsigned long *hw_cr0,
>> unsigned long cr0,
>> struct kvm_vcpu *vcpu)
>> {
>> ....
>> } else if (!is_paging(vcpu)) {
>> /* From nonpaging to paging */
>> vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
>> vmcs_read32(CPU_BASED_VM_EXEC_CONTROL) &
>> - ~(CPU_BASED_CR3_LOAD_EXITING |
>> + ~( // CPU_BASED_CR3_LOAD_EXITING|
>> CPU_BASED_CR3_STORE_EXITING));
>> ....
>> }
>>
>> static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>> {
>> ...
>> if (_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_EPT) {
>> /* CR3 accesses and invlpg don't need to cause VM Exits when EPT
>> enabled */
>> - _cpu_based_exec_control &= ~(CPU_BASED_CR3_LOAD_EXITING |
>> + _cpu_based_exec_control &= ~( //
>> CPU_BASED_CR3_LOAD_EXITING |
>> CPU_BASED_CR3_STORE_EXITING |
>> CPU_BASED_INVLPG_EXITING);
>> ....
>> }
>>
>> I though it can force every Cr3 access to be trapped with EPT enable.
>> However, VM seems to fail to boot when it changes from nonpaging to
>> paging.
>> Do U guys have any idea? Or Can someone tell me how can I intercept
>> Cr3 access and why can not it work?
>>
>> Thank U for answering.
>
>>
>> --
>> Thanks
>> Rui Wu
>> --
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--
Thanks
Rui Wu
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