Subject: [PATCH 0/6] KVM: Remove uses of struct page from x86 and arm64 MMU

From: David Stevens <[email-masked]>
Date: Thu, 24 Jun 2021 12:57:43 +0900

KVM supports mapping VM_IO and VM_PFNMAP memory into the guest by using
follow_pte in gfn_to_pfn. However, the resolved pfns may not have
assoicated struct pages, so they should not be passed to pfn_to_page.
This series removes such calls from the x86 and arm64 secondary MMU. To
do this, this series modifies gfn_to_pfn to return a struct page in
addition to a pfn, if the hva was resolved by gup. This allows the
caller to call put_page only when necessated by gup.

This series provides a helper function that unwraps the new return type
of gfn_to_pfn to provide behavior identical to the old behavior. As I
have no hardware to test powerpc/mips changes, the function is used
there for minimally invasive changes. Additionally, as gfn_to_page and
gfn_to_pfn_cache are not integrated with mmu notifier, they cannot be
easily changed over to only use pfns.

This addresses CVE-2021-22543 on x86 and arm64.

David Stevens (6):
  KVM: x86/mmu: release audited pfns
  KVM: mmu: also return page from gfn_to_pfn
  KVM: x86/mmu: avoid struct page in MMU
  KVM: arm64/mmu: avoid struct page in MMU
  KVM: mmu: remove over-aggressive warnings
  drm/i915/gvt: use gfn_to_pfn's page instead of pfn

 arch/arm64/kvm/mmu.c                   |  42 +++++----
 arch/mips/kvm/mmu.c                    |   3 +-
 arch/powerpc/kvm/book3s.c              |   3 +-
 arch/powerpc/kvm/book3s_64_mmu_hv.c    |   5 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c |   5 +-
 arch/powerpc/kvm/book3s_hv_uvmem.c     |   4 +-
 arch/powerpc/kvm/e500_mmu_host.c       |   2 +-
 arch/x86/kvm/mmu/mmu.c                 |  60 ++++++------
 arch/x86/kvm/mmu/mmu_audit.c           |  13 ++-
 arch/x86/kvm/mmu/mmu_internal.h        |   3 +-
 arch/x86/kvm/mmu/paging_tmpl.h         |  36 +++++---
 arch/x86/kvm/mmu/tdp_mmu.c             |   7 +-
 arch/x86/kvm/mmu/tdp_mmu.h             |   4 +-
 arch/x86/kvm/x86.c                     |   9 +-
 drivers/gpu/drm/i915/gvt/gtt.c         |  12 ++-
 drivers/gpu/drm/i915/gvt/hypercall.h   |   3 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c       |  12 +--
 drivers/gpu/drm/i915/gvt/mpt.h         |   8 +-
 include/linux/kvm_host.h               |  27 ++++--
 include/linux/kvm_types.h              |   5 +
 virt/kvm/kvm_main.c                    | 123 +++++++++++++------------
 21 files changed, 212 insertions(+), 174 deletions(-)

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2.32.0.93.g670b81a890-goog