Re: [PATCH 3/5] mmu: don't set the present bit unconditionally

Xiao Guangrong
2016-06-30T07:18:31Z

On 06/29/2016 04:18 PM, Paolo Bonzini wrote:
>
>
> On 29/06/2016 05:17, Xiao Guangrong wrote:
>>>
>>> +++ b/arch/x86/kvm/mmu.c
>>> @@ -2516,13 +2516,17 @@ static int set_spte(struct kvm_vcpu *vcpu, u64
>>> *sptep,
>>> gfn_t gfn, kvm_pfn_t pfn, bool speculative,
>>> bool can_unsync, bool host_writable)
>>> {
>>> - u64 spte;
>>> + u64 spte = 0;
>>> int ret = 0;
>>> + struct kvm_mmu *context = &vcpu->arch.mmu;
>>> + bool execonly = !(context->guest_rsvd_check.bad_mt_xwr &
>>> + (1ull << VMX_EPT_EXECUTABLE_MASK));
>>
>> Could we introduce a new field, say execonly, to "struct kvm_mmu"?
>> That would make the code be more clearer.
>
> Given how execonly is used, let's add shadow_present_mask instead.

Yup, it is better.