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

[Paolo Bonzini <pbonzini@redhat.com>]

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;