Hello,
I am trying to set up a shared page between the hypervisor and a Linux guest
kernel. In Xen I am doing:
void *ptr = alloc_xenheap_page();
share_xen_page_with_guest(virt_to_page(ptr), current->domain,
XENSHARE_writable);
unsigned int mfn = virt_to_mfn(ptr);
And my plan was to pass the mfn to the guest kernel and retrieve the pfn with
mfn_to_pfn(). However, this returned ~0.
So I took a look at share_xen_page_with_guest() and I noticed it calls
set_gpfn_from_mfn(mfn, INVALID_M2P_ENTRY),
where INVALID_M2P_ENTRY = ~0.
My questions are:
1. Do I have to call set_gpfn_from_mfn() after calling
share_xen_page_with_guest() in the hypervisor?
2. If yes, what gpfn should I use? I am thinking I could allocate a
page in the guest, and retrieve the pfn with page_to_pfn(),
and then pass that to the hypervisor. But I don’t know if I am
overcomplicating things.
Thank you for your help,
Emmanuel
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