From 85c8555ff07ef09261bd50d603cd4290cff5a8cc Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Fri, 12 Sep 2014 15:16:00 +0200
Subject: [PATCH] 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: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
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 33712fb26eb11..96ec6226e4ab6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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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