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

From: Jason Wang
Date: Fri Sep 11 2015 - 05:27:03 EST




On 09/11/2015 04:31 PM, Cornelia Huck wrote:
> On Fri, 11 Sep 2015 10:26:41 +0200
> Paolo Bonzini <pbonzini@xxxxxxxxxx> 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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