[PATCH v6 0/4] KVM: mm: count KVM mmu usage in memory stats

[Yosry Ahmed <yosryahmed@google.com>]

Add NR_SECONDARY_PAGETABLE memory stat and use it to account KVM mmu
usage as the first type of accounted secondary page tables. This stat
can be later extended to account for other types of secondary pages
tables (e.g. iommu page tables).

Rationale behind why this is useful and link to extended discussion in
the first patch.

---

Changes in V6:
- Rebased on top of kvm/queue and fixed conflicts.
- Fixed docs spaces and tabs (Sean).
- More narrative commit logs (Sean and Oliver).
- Updated kvm_account_pgtable_pages() documentation to describe the
  rules of using it more clearly (Sean).
- Collected Acks and Reviewed-by's by Shakeel and Oliver (Thanks!)

Changes in V5:
- Updated cover letter to explain more the rationale behind the change
  (Thanks to contributions by Sean Christopherson).
- Removed extraneous + in arm64 patch (Oliver Upton, Marc Zyngier).
- Shortened secondary_pagetables to sec_pagetables (Shakeel Butt).
- Removed dependency on other patchsets (applies to queue branch).

Changes in V4:
- Changed accounting hooks in arm64 to only account s2 page tables and
  refactored them to a much cleaner form, based on recommendations from
  Oliver Upton and Marc Zyngier.
- Dropped patches for mips and riscv. I am not interested in those archs
  anyway and don't have the resources to test them. I posted them for
  completeness but it doesn't seem like anyone was interested.

Changes in V3:
- Added NR_SECONDARY_PAGETABLE instead of piggybacking on NR_PAGETABLE
  stats.

Changes in V2:
- Added accounting stats for other archs than x86.
- Changed locations in the code where x86 KVM page table stats were
  accounted based on suggestions from Sean Christopherson.

---

Yosry Ahmed (4):
  mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses.
  KVM: mmu: add a helper to account memory used by KVM MMU.
  KVM: x86/mmu: count KVM mmu usage in secondary pagetable stats.
  KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats

 Documentation/admin-guide/cgroup-v2.rst |  5 ++++
 Documentation/filesystems/proc.rst      |  4 +++
 arch/arm64/kvm/mmu.c                    | 36 ++++++++++++++++++++++---
 arch/x86/kvm/mmu/mmu.c                  | 16 +++++++++--
 arch/x86/kvm/mmu/tdp_mmu.c              | 12 +++++++++
 drivers/base/node.c                     |  2 ++
 fs/proc/meminfo.c                       |  2 ++
 include/linux/kvm_host.h                | 10 +++++++
 include/linux/mmzone.h                  |  1 +
 mm/memcontrol.c                         |  1 +
 mm/page_alloc.c                         |  6 ++++-
 mm/vmstat.c                             |  1 +
 12 files changed, 89 insertions(+), 7 deletions(-)

-- 
2.37.0.rc0.161.g10f37bed90-goog