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

From: Paolo Bonzini
Date: Fri Sep 11 2015 - 04:26:50 EST




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;
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