Re: xc_altp2m_set_vcpu_enable_notify fail

[Big Strong <fangtuo90@gmail.com>]

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I just set the domid to DOMID_SELF to pass the check, but another problem
is how to assign the gfn used to store #ve infomation. As I'm doing all the
things in user space, directly assign a new physical page seems impossible.
While LKM can do that with kmalloc and virt_to_phys, it cannot call user
space functions of libxc. Is there a libxc function to translate the
virtual address of malloc() to physical address?

2016-05-16 23:05 GMT+08:00 Big Strong <fangtuo90@gmail.com>:

> To solve that, I install xen and tools in the guest, so as to access its
> domain id and vcpu info to overcome the 'domain is null' error. Now the
> problem is solved, but errors comes at 'domain != DOMID_SELF' checking
> <http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/hvm.c;h=7492030a131a4212d9ca8e700621b2c8836867a9;hb=4f6aea066fe2cf3bf4929d6dac1e558071566f73#l5238>.
> The DOMID_SELF is always 32752 (0x7FF0), while a.domain is the domid of the
> guest, which induce the checking failed and exit. Any helps?
>
>
> 2016-05-16 17:06 GMT+08:00 Big Strong <fangtuo90@gmail.com>:
>
>> Your opinion is inspiring. During the past days, I've tried to directly
>> call HVMOP_altp2m_vcpu_enable_notify in guest by ioctl, this time it fails
>> for "domain is null" checking.
>> <http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/hvm.c;h=7492030a131a4212d9ca8e700621b2c8836867a9;hb=4f6aea066fe2cf3bf4929d6dac1e558071566f73#l5167> I
>> thought it might because the guest is not able to achieve the vcpu info
>> of its current state
>> <http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/hvm.c;h=7492030a131a4212d9ca8e700621b2c8836867a9;hb=4f6aea066fe2cf3bf4929d6dac1e558071566f73#l5164>.
>> While in dom0, this is not a problem. But dom0 is unable to
>> call  HVMOP_altp2m_vcpu_enable_notify for the guest. How can I solve this
>> contradiction?
>>
>> 2016-05-12 23:17 GMT+08:00 Wei Liu <wei.liu2@citrix.com>:
>>
>>> On Thu, May 12, 2016 at 09:00:12PM +0800, Big Strong wrote:
>>> > I'm still not very clear why would do_altp2m_op change the domain to
>>> > current domain (which is dom0 in my case) when the cmd is
>>> > HVMOP_altp2m_vcpu_enable_notify
>>> > <
>>> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/hvm.c;hb=743289d0296268fe6bad64531a24d8053afeb062#l6198
>>> >.
>>> > As to my case, it would prevent the dom0 to set the #ve info page for
>>> other
>>> > domUs because the check of is_hvm_domain would fail
>>> > <
>>> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/hvm/hvm.c;hb=743289d0296268fe6bad64531a24d8053afeb062#l6204
>>> >and
>>> > the function will returns directly.
>>> >
>>>
>>> Maybe the intent of that HVMOP is to get called directly by the guest
>>> that is interested in such event?
>>>
>>> I looks like a natural restriction to me because the vcpu needs to set
>>> up handler for #ve AIUI. It's not likely that Dom0 can do this for
>>> arbitrary guest.
>>>
>>> Wei.
>>>
>>
>>
>

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