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KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn()

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Read-only memory ranges may be backed by the zero page, so avoid
misidentifying it a a MMIO pfn.

This fixes another issue I identified when testing QEMU+KVM_UEFI, where
a read to an uninitialized emulated NOR flash brought in the zero page,
but mapped as a read-write device region, because kvm_is_mmio_pfn()
misidentifies it as a MMIO pfn due to its PG_reserved bit being set.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Fixes: b88657674d ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ard Biesheuvel 2014-09-12 15:16:00 +02:00 committed by Paolo Bonzini
parent 0b70068e47
commit 85c8555ff0
1 changed files with 1 additions and 1 deletions
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2
virt/kvm/kvm_main.c
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@ -110,7 +110,7 @@ static bool largepages_enabled = true;
bool kvm_is_mmio_pfn(pfn_t pfn)
{
if (pfn_valid(pfn))
return PageReserved(pfn_to_page(pfn));
return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn));
return true;
}