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SubjectRe: [PATCH v2 5/5] KVM: x86: improve reexecute_instruction
On 12/14/2012 07:02 AM, Marcelo Tosatti wrote:

>>> Same comment as before: the only case where it should not attempt to
>>> emulate is when there is a condition which makes it impossible to fix
>>> (the information is available to detect that condition).
>>>
>>> The earlier suggestion
>>>
>>> "How about recording the gfn number for shadow pages that have been
>>> shadowed in the current pagefault run?"
>>>
>>> Was about that.
>>
>> I think we can have a try. Is this change good to you, Marcelo?
>>
>> [eric@localhost kvm]$ git diff
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index 01d7c2a..e3d0001 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -4359,24 +4359,34 @@ unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
>> return nr_mmu_pages;
>> }
>>
>> -int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4])
>> +void kvm_mmu_get_sp_hierarchy(struct kvm_vcpu *vcpu, u64 addr,
>> + struct kvm_mmu_sp_hierarchy *hierarchy)
>> {
>> struct kvm_shadow_walk_iterator iterator;
>> u64 spte;
>> - int nr_sptes = 0;
>> +
>> + hierarchy->max_level = hierarchy->nr_levels = 0;
>>
>> walk_shadow_page_lockless_begin(vcpu);
>> for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
>> - sptes[iterator.level-1] = spte;
>> - nr_sptes++;
>> + struct kvm_mmu_page *sp = page_header(__pa(iterator.sptep));
>> +
>> + if (hierarchy->indirect_only && sp->role.direct)
>> + break;
>> +
>> + if (!hierarchy->max_level)
>> + hierarchy->max_level = iterator.level;
>> +
>> + hierarchy->shadow_gfns[iterator.level-1] = sp->gfn;
>> + hierarchy->sptes[iterator.level-1] = spte;
>> + hierarchy->nr_levels++;
>> +
>> if (!is_shadow_present_pte(spte))
>> break;
>> }
>> walk_shadow_page_lockless_end(vcpu);
>> -
>> - return nr_sptes;
>> }
>
> Record gfns while shadowing in the vcpu struct, in a struct, along with cr2.
> Then validate
> That way its guaranteed its not some other vcpu.

Okay, i will try this way. :)




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