Re: [PATCH] KVM MMU: check reserved bits only if CR4.PSE=1 or CR4.PAE=1

Xiao Guangrong
2010-03-16T06:06:51Z

Avi Kivity wrote:
> On 03/16/2010 08:21 PM, Xiao Guangrong wrote:
>> The RSV bit is possibility set in error code when #PF occurred
>> only if CR4.PSE=1 or CR4.PAE=1
>>
>> Signed-off-by: Xiao Guangrong<xiaoguangrong@cn.fujitsu.com>
>> ---
>> arch/x86/kvm/mmu.c | 3 +++
>> 1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index 741373e..36e50ab 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -2270,6 +2270,9 @@ static bool is_rsvd_bits_set(struct kvm_vcpu
>> *vcpu, u64 gpte, int level)
>> {
>> int bit7;
>>
>> + if (!is_pae(vcpu)&& !is_pse(vcpu))
>> + return 0;
>> +
>> bit7 = (gpte>> 7)& 1;
>> return (gpte& vcpu->arch.mmu.rsvd_bits_mask[bit7][level-1]) != 0;
>> }
>>
>
> Should be handled by reset_rsvd_bits_mask(), so that all reserved bit
> handling happens in one place.
>

OK, will fix it.

> I think the only change is that is !is_pse(vcpu) we ignore bit 7?

If the vcpu is in PT32E_ROOT_LEVEL/PT64_ROOT_LEVEL mode, CR4.PAE
is aways enabled, so what we need do is ignore bit7 if !is_pse(vcpu)
under PT32_ROOT_LEVEL mode, right?

Thanks,
Xiao