Subject: Re: [PATCH v2 14/15] KVM: Terminate memslot walks via used_slots

From: Paolo Bonzini <[email-masked]>
Date: Tue, 22 Oct 2019 17:30:58 +0200

On 22/10/19 17:28, Sean Christopherson wrote:
> On Tue, Oct 22, 2019 at 04:04:18PM +0200, Paolo Bonzini wrote:
>> On 22/10/19 02:35, Sean Christopherson wrote:
>>> +static inline int kvm_shift_memslots_forward(struct kvm_memslots *slots,
>>> +					     struct kvm_memory_slot *new)
>>> +{
>>> +	struct kvm_memory_slot *mslots = slots->memslots;
>>> +	int i;
>>> +
>>> +	if (WARN_ON_ONCE(slots->id_to_index[new->id] == -1) ||
>>> +	    WARN_ON_ONCE(!slots->used_slots))
>>> +		return -1;
>>> +
>>> +	for (i = slots->id_to_index[new->id]; i < slots->used_slots - 1; i++) {
>>> +		if (new->base_gfn > mslots[i + 1].base_gfn)
>>> +			break;
>>> +
>>> +		WARN_ON_ONCE(new->base_gfn == mslots[i + 1].base_gfn);
>>> +
>>> +		/* Shift the next memslot forward one and update its index. */
>>> +		mslots[i] = mslots[i + 1];
>>> +		slots->id_to_index[mslots[i].id] = i;
>>> +	}
>>> +	return i;
>>> +}
>>> +
>>> +static inline int kvm_shift_memslots_back(struct kvm_memslots *slots,
>>> +					  struct kvm_memory_slot *new,
>>> +					  int start)
>>
>> This new implementation of the insertion sort loses the comments that
>> were there in the old one.  Please keep them as function comments.
> 
> I assume you're talking about this blurb in particular?
> 
> 	 * The ">=" is needed when creating a slot with base_gfn == 0,
> 	 * so that it moves before all those with base_gfn == npages == 0.

Yes, well all of the comments.  You can also keep them in the caller, as
you prefer.

Paolo

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