HV KVM fails on 970 due to HTAB allocation

[Alexander Graf <agraf@suse.de>]

Hi Paul,

While trying to run HV KVM for something useful on 970, we stumbled over 
the following code path:

         /* Allocate guest's hashed page table */
         hpt = 
__get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|__GFP_NOWARN,
                                HPT_ORDER - PAGE_SHIFT);
         if (!hpt) {
                 pr_err("kvm_alloc_hpt: Couldn't alloc HPT\n");
                 return -ENOMEM;
         }
         kvm->arch.hpt_virt = hpt;

We're most of the time running into the !hpt case, because we simply 
don't have 16MB of contiguous memory lying around.

I was trying to check if we could maybe allocate a huge_tlb page from 
within kernel space, since that usually matches the 16MB pretty well. 
However that seems to be very tricky. Maybe something similar to the RMA 
thing would be a good idea?


Alex