Re: user-allocated memory

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Carsten Otte wrote:
> Izik Eidus wrote:
>   
>> we are working on swapping support for the guests in kvm.
>> we want to allow management of the memory swapping of the guests from kvm.
>>     
> This is excellent, thank you!
>
>   
>> this is request for comment, so any idea you have please write to me.
>>     
> I ran into a few while reading the code:
>
> +static void kvm_free_userspace_physmem(struct kvm_memory_slot *free)
> +{
> +	int i;
> +	
> +	for (i = 0; i < free->npages; ++i) {
> +		if (free->phys_mem[i]) {
> +			if (!PageReserved(free->phys_mem[i]))
> +				SetPageDirty(free->phys_mem[i]);
> +			page_cache_release(free->phys_mem[i]);
> +		}
> +	}
> +}
> I don't see why we would want to dirty a page we release in general. 
> We do only need to dirty it, if the corresponding page table entry 
> indicates so (dirty bit). Did I miss something?
>
>   

kvm only tracks dirty bits if requested by userspace (for live 
migration).  Checking the pte is not so easy because the pte contains 
only host addresses, not page addresses (well, we could consult the 
guest page table, but...).

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


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