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

Avi Kivity
2010-03-16T05:31:47Z

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.

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

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.