linux-kernel - Re: [PATCH V4 3/4] kvm: fix zero length mmio searching

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Date:	Fri, 11 Sep 2015 17:26:54 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	Cornelia Huck <cornelia.huck@...ibm.com>,
	Paolo Bonzini <pbonzini@...hat.com>
Cc:	gleb@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	mst@...hat.com
Subject: Re: [PATCH V4 3/4] kvm: fix zero length mmio searching



On 09/11/2015 04:31 PM, Cornelia Huck wrote:
> On Fri, 11 Sep 2015 10:26:41 +0200
> Paolo Bonzini <pbonzini@...hat.com> wrote:
>
>> On 11/09/2015 05:17, Jason Wang wrote:
>>> +	int len = r2->len ? r1->len : 0;
>>> +
>>>  	if (r1->addr < r2->addr)
>>>  		return -1;
>>> -	if (r1->addr + r1->len > r2->addr + r2->len)
>>> +	if (r1->addr + len > r2->addr + r2->len)
>>>  		return 1;
>> Perhaps better:
>>
>> 	gpa_t addr1 = r1->addr;
>> 	gpa_t addr2 = r2->addr;
>>
>> 	if (addr1 < addr2)
>> 		return -1;
>>
>> 	/* If r2->len == 0, match the exact address.  If r2->len != 0,
>> 	 * accept any overlapping write.  Any order is acceptable for
>> 	 * overlapping ranges, because kvm_io_bus_get_first_dev ensures
>> 	 * we process all of them.
>> 	 */
>> 	if (r2->len) {
>> 		addr1 += r1->len;
>> 		addr2 += r2->len;
>> 	}
>>
>> 	if (addr1 > addr2)
>> 		return 1;
>>
>> 	return 0;
>>
> +1 to documenting what the semantics are :)
>

Right, better. Will fix this in V5.
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