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SubjectRe: [PATCH] KVM: x86: Fix page-tables reserved bits
On Fri, Apr 04, 2014 at 06:31:04AM +0300, Nadav Amit wrote:
> KVM does not handle the reserved bits of x86 page tables correctly:
> In PAE, bits 5:8 are reserved in the PDPTE.
> In IA-32e, bit 8 is not reserved.
>
> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
> ---
> arch/x86/kvm/mmu.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index f5704d9..3993976 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -3538,7 +3538,7 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
> case PT32E_ROOT_LEVEL:
> context->rsvd_bits_mask[0][2] =
> rsvd_bits(maxphyaddr, 63) |
> - rsvd_bits(7, 8) | rsvd_bits(1, 2); /* PDPTE */
> + rsvd_bits(5, 8) | rsvd_bits(1, 2); /* PDPTE */
> context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
> rsvd_bits(maxphyaddr, 62); /* PDE */
> context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
> @@ -3550,9 +3550,9 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
> break;
> case PT64_ROOT_LEVEL:
> context->rsvd_bits_mask[0][3] = exb_bit_rsvd |
> - rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
> + rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 7);
> context->rsvd_bits_mask[0][2] = exb_bit_rsvd |
> - rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
> + rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 7);

Bit 7 is not reserved either, for the PDPTE (its PageSize bit).



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