Re: Rename restrictedmem => guardedmem? (was: Re: [PATCH v10 0/9] KVM: mm: fd-based approach for supporting KVM)

[Ackerley Tng]

I've ported selftests from Chao and I [1] while working on hugetlb support  
for
guest_mem [2].

In the process, I found some bugs and have some suggestions for guest_mem.
Please see separate commits at [3].

Here are some highlights/questions:

+ "KVM: guest_mem: Explain the use of the uptodate flag for gmem"
    + Generally, uptodate flags means that the contents of this page match  
the
      backing store. Since gmem is memory-backed, does "uptodate" for gmem  
mean
      "zeroed"?
+ "KVM: guest_mem: Don't re-mark accessed after getting a folio" and "KVM:
  guest_mem: Don't set dirty flag for folio"
    + Do we need to folio_mark_accessed(), when it was created with
      FGP_ACCESSED?
    + What is the significance of these LRU flags when gmem doesn't support
      swapping/eviction?
+ "KVM: guest_mem: Align so that at least 1 page is allocated"
    + Bug in current implementation: without this alignment, fallocate() of  
a
      size less than the gmem page size will result in no allocation at all
    + Both shmem and hugetlbfs perform this alignment
+ "KVM: guest_mem: Add alignment checks"
    + Implemented the alignment checks for guest_mem because hugetlb on gmem
      would hit a BUG_ON without this check
+ "KVM: guest_mem: Prevent overflows in kvm_gmem_invalidate_begin()"
    + Sean fixed a bug in the offset-to-gfn conversion in
      kvm_gmem_invalidate_begin() earlier, adding a WARN_ON_ONCE()
    + Code will always hit WARN_ON_ONCE() when the entire file is closed  
and all
      offsets are invalidated, so WARN_ON_ONCE() should be removed
    + Vishal noticed that the conversion might result in an overflow, so I  
fixed
      that
+ And of course, hugetlb support! Please let me know what you think of the
  approach proposed at [2].

[1]  
https://lore.kernel.org/all/cover.1678926164.git.ackerleytng@xxxxxxxxxx/T/
[2]  
https://lore.kernel.org/lkml/cover.1686077275.git.ackerleytng@xxxxxxxxxx/T/
[3] https://github.com/googleprodkernel/linux-cc/tree/gmem-hugetlb-rfc-v1