Commit 85c8555f authored Sep 12, 2014 by Ard Biesheuvel Committed by Paolo Bonzini Sep 14, 2014

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

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: b8865767 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 0b70068e

virt/kvm/kvm_main.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}

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