KVM: arm64: Use stage-1 leaf size for VM_PFNMAP

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When commit 2aa53d68ce ("KVM: arm64: Try stage2 block mapping for
host device MMIO") added VM_PFNMAP support to get_vma_page_shift(),
stage-1 page tables did not support huge PFNMAP (as in VFIO-PCI
vfio_pci_mmap_huge_fault()) and transparent_hugepage_adjust() was
unsafe for MMIO as it dereferenced struct page.

Since commit 6011cf68c8 ("KVM: arm64: Walk userspace page tables to
compute the THP mapping size"), transparent_hugepage_adjust() instead
walks the host stage-1 page tables via get_user_mapping_size() without
touching struct page. Meanwhile, commit 3e509c9b03 ("mm/arm64:
support large pfn mappings") enabled stage-1 huge PFNMAP.

So. we can drop the VMA-based VM_PFNMAP size calculation in
get_vma_page_shift() and let transparent_hugepage_adjust() derive
the stage-2 mapping size directly from the populated stage-1 leaf
for non-cacheable mappings as well.

Assisted-by: LLM
Cc: stable@vger.kernel.org
Fixes: 2aa53d68ce ("KVM: arm64: Try stage2 block mapping for host device MMIO")
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Oliver Upton <oupton@kernel.org>

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Mostafa Saleh 2026-09-29 20:02:09 +00:00 • committed by Oliver Upton

parent afb4334fb5

commit 71cc2c67fb

1 changed files with 6 additions and 41 deletions

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arch/arm64/kvm/mmu.c

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