* [PATCH] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn()
@ 2014-09-12 13:16 Ard Biesheuvel
2014-09-12 13:36 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Ard Biesheuvel @ 2014-09-12 13:16 UTC (permalink / raw)
To: gleb, pbonzini, marc.zyngier, christoffer.dall, kvm, kvmarm,
steve.capper
Cc: lersek, fu.wei, peter.maydell, Ard Biesheuvel
Read-only memory ranges may be backed by the zero page, so avoid
misidentifying it a a MMIO pfn.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Fixes: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
---
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.
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 36b887dd0c84..f8adaabeac13 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;
}
--
1.8.3.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn()
2014-09-12 13:16 [PATCH] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn() Ard Biesheuvel
@ 2014-09-12 13:36 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2014-09-12 13:36 UTC (permalink / raw)
To: Ard Biesheuvel, gleb, marc.zyngier, christoffer.dall, kvm, kvmarm,
steve.capper
Cc: lersek, fu.wei, peter.maydell
Il 12/09/2014 15:16, Ard Biesheuvel ha scritto:
> Read-only memory ranges may be backed by the zero page, so avoid
> misidentifying it a a MMIO pfn.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Fixes: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping")
> ---
>
> 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.
>
> 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 36b887dd0c84..f8adaabeac13 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;
> }
>
Thanks, applying to kvm/master.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-09-12 13:16 [PATCH] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn() Ard Biesheuvel
2014-09-12 13:36 ` Paolo Bonzini
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