From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 85c8555ff07ef09261bd50d603cd4290cff5a8cc upstream.
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@xxxxxxxxxx>
Fixes: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3351605d2608..e7a1166c3eb4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -104,7 +104,7 @@ 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;
}
--
2.10.2
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