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KVM: arm64: Update page shift if stage 2 block mapping not supported
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Commit 196f878 (" KVM: arm/arm64: Signal SIGBUS when stage2 discovers
hwpoison memory") modifies user_mem_abort() to send a SIGBUS signal when
the fault IPA maps to a hwpoisoned page. Commit 1559b75 ("KVM:
arm/arm64: Re-check VMA on detecting a poisoned page") changed
kvm_send_hwpoison_signal() to use the page shift instead of the VMA because
at that point the code had already released the mmap lock, which means
userspace could have modified the VMA.

If userspace uses hugetlbfs for the VM memory, user_mem_abort() tries to
map the guest fault IPA using block mappings in stage 2. That is not always
possible, if, for example, userspace uses dirty page logging for the VM.
Update the page shift appropriately in those cases when we downgrade the
stage 2 entry from a block mapping to a page.

Fixes: 1559b75 ("KVM: arm/arm64: Re-check VMA on detecting a poisoned page")
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20200901133357.52640-2-alexandru.elisei@arm.com
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Alexandru Elisei authored and Marc Zyngier committed Sep 4, 2020
1 parent 376426b commit 7b75cd5
Showing 1 changed file with 1 addition and 0 deletions.
1 change: 1 addition & 0 deletions arch/arm64/kvm/mmu.c
Original file line number Diff line number Diff line change
Expand Up @@ -1871,6 +1871,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
!fault_supports_stage2_huge_mapping(memslot, hva, vma_pagesize)) {
force_pte = true;
vma_pagesize = PAGE_SIZE;
vma_shift = PAGE_SHIFT;
}

/*
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