Re: [patch 2/5] KVM: hypercall based pte updates and TLB flushes

[Avi Kivity <avi@qumranet.com>]

Avi Kivity wrote:
> Marcelo Tosatti wrote:
>> Hypercall based pte updates are faster than faults, and also allow use
>> of the lazy MMU mode to batch operations.
>>
>> Don't report the feature if two dimensional paging is enabled.
>>
>> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>> +/*
>> + * We only need to hook operations that are MMU writes.  We hook 
>> these so that
>> + * we can use lazy MMU mode to batch these operations.  We could 
>> probably
>> + * improve the performance of the host code if we used some of the 
>> information
>> + * here to simplify processing of batched writes.
>> + */
>>   
>
> One option is, if the guest promises never to write to a page table 
> directly, is to avoid write protecting guest page tables.  I think the 
> shadow code can handle it (since the gfn/spte relationship is 
> maintained by shadow code, and doesn't require reading the guest page 
> tables), but am not sure.
>

In addition to reducing mmu work for write protection, this allows more 
efficient use of large pages.

-- 
error compiling committee.c: too many arguments to function


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