Avi Kivity wrote:
> On 05/31/2010 05:00 AM, Xiao Guangrong wrote:
>>
>>>
>>>> +
>>>> +#define for_each_gfn_indirect_sp(kvm, sp, gfn, pos, n) \
>>>> + hlist_for_each_entry_safe(sp, pos, n, \
>>>> +&kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)], hash_link)\
>>>> + if (sp->gfn == gfn&& !sp->role.direct)
>>>> +
>>>> +#define for_each_gfn_indirect_valid_sp(kvm, sp, gfn, pos, n) \
>>>> + hlist_for_each_entry_safe(sp, pos, n, \
>>>> +&kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)], hash_link)\
>>>> + if (sp->gfn == gfn&& !sp->role.direct&& \
>>>> + !sp->role.invalid)
>>>>
>>>>
>>> Shouldn't we always skip invalid gfns?
>>>
>> Actually, in kvm_mmu_unprotect_page() function, it need find out
>> invalid shadow pages:
>>
>> | hlist_for_each_entry_safe(sp, node, n, bucket, hash_link)
>> | if (sp->gfn == gfn&& !sp->role.direct) {
>> | pgprintk("%s: gfn %lx role %x\n", __func__, gfn,
>> | sp->role.word);
>> | r = 1;
>> | if (kvm_mmu_zap_page(kvm, sp))
>> | goto restart;
>> | }
>>
>> I'm not sure whether we can skip invalid sp here, since it can change
>> this
>> function's return value. :-(
>>
>
> Hm. Invalid pages don't need to be write protected. So I think you can
> patch unprotect_page() to ignore invalid pages, and then you can convert
> it to the new macros which ignore invalid pages as well.
>
> The invariant is: if an sp exists with !role.invalid and !unsync, then
> the page must be write protected.
OK, will fix it in the next version.
>
>
>>> What about providing both gfn and role to the macro?
>>>
>>>
>> In current code, no code simply use role and gfn to find sp,
>> in kvm_mmu_get_page(), we need do other work for
>> 'sp->gfn == gfn&& sp->role != role' sp, and other functions only need
>> compare
>> some members in role, but not all members.
>>
>
> How about just gfn? I think everything compares against that!
>
In this patch, it already introduced a macro to only compares 'gfn', that is:
+#define for_each_gfn_sp(kvm, sp, gfn, pos, n) \
+ hlist_for_each_entry_safe(sp, pos, n, \
+ &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)], hash_link)\
+ if (sp->gfn == gfn)
Sorry if i misunderstand your meaning.
Thanks,
Xiao
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