Re: [Xen-devel] xc_altp2m_set_vcpu_enable_notify fail

[Big Strong <fangtuo90@xxxxxxxxx>]

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@xxxxxxxxx>:

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. 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@xxxxxxxxx>:

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. I thought it might because the guest is not able to achieve the vcpu info of its current state. 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@xxxxxxxxxx>:

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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