Re: [PATCH] KVM: x86: Fix page-tables reserved bits

From: H. Peter Anvin
Date: Wed Apr 16 2014 - 17:17:48 EST


On 04/16/2014 12:03 PM, Marcelo Tosatti wrote:
>> @@ -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).
>

In long mode (IA-32e), bit 7 is definitely reserved.

-hpa

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