problems about EPT in kvm

problems about EPT in kvm

[xitler adole]

Dear developer:

I am facing confusing problems, there is no way for me to figure it
out, so I have to ask for help:

1.  I am using the <asm/kvm_host.h> <linux/kvm_host.h> for using kvm
in my module, but there are always some function undefined like
kvm_arch_mmu_notifier_invalidate_range. Are those functions not
visiable from outside?

2.   With the ept technology, If I use "alloc_page" inside the guest
virtual machine, and use "page_to_pfn" to get the pfn of the certain
page, Is the pfn I get the gfn or the pfn of the host machine?

3.  I want to modify the EPT table, so that I can make the gva point
to certain hpa just to share information between vm, Given the
condition that I can not modify the kvm code, Is that possible?

4. Do you have some technology about sharing memory between virtual
machine with some example code?

sorry for trouble, but I really find it hart to solve it only by myself.

Re: problems about EPT in kvm

[Vitaly Kuznetsov]

xitler adole <zqyleo@gmail.com> writes:

> Dear developer:
>
> I am facing confusing problems, there is no way for me to figure it
> out, so I have to ask for help:
>
> 1.  I am using the <asm/kvm_host.h> <linux/kvm_host.h> for using kvm
> in my module, but there are always some function undefined like
> kvm_arch_mmu_notifier_invalidate_range. Are those functions not
> visiable from outside?

kvm_arch_mmu_notifier_invalidate_range() is not exported to other
modules with EXPORT_SYMBOL_GPL() so you won't be able to call it.

>
> 2.   With the ept technology, If I use "alloc_page" inside the guest
> virtual machine, and use "page_to_pfn" to get the pfn of the certain
> page, Is the pfn I get the gfn or the pfn of the host machine?

You'll get gfn. Basically, the guest doesn't know that it runs as guest.

>
> 3.  I want to modify the EPT table, so that I can make the gva point
> to certain hpa just to share information between vm, Given the
> condition that I can not modify the kvm code, Is that possible?

You have two level of translation:

GVA -> GPA
GPA -> HPA

so to make it happen you'll need a maping inside the guest (GVA -> GPA)
+ an entry in EPT (GPA -> HPA).

-- 
Vitaly