[igt-dev] [PATCH i-g-t] i915: Add gem_vm_create

[Tvrtko Ursulin]

On 01/04/2019 09:52, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-04-01 09:12:08)
>>
>>
>> On 30/03/2019 10:29, Chris Wilson wrote:
>>> +     /* Verify the trick with the assumed target works */
>>> +     write_to_address(i915, ctx[0], obj[0].offset, i915);
>>> +     gem_read(i915, obj[0].handle, 0, &result, sizeof(result));
>>> +     igt_assert_eq(result, i915);
>>> +
>>> +     /* Now check that we can't write to vm[0] from second fd/vm */
>>> +     write_to_address(other, ctx[1], obj[0].offset, other);
>>> +     gem_read(i915, obj[0].handle, 0, &result, sizeof(result));
>>> +     igt_assert_eq(result, i915);
>>> +
>>
>> Relies on objects being zeroes (check) and neither fd being zero. To be
>> safe add asserts for the latter?
> 
> Just replace i915,other there with 1,2. Objects are verified to be zero
> in other tests, and it's a core piece of ABI that we don't allow
> information leaks so easily.

I know, the "check" in parentheses was supposed to mean a ticked 
checkbox kind of check. I wasn't clear at all. :( So I was just saying 
to put in a quick assert neither fd is zero. Or if we cannot ever 
imagine running IGT with closed stdin maybe it doesn't matter.

Regards,

Tvrtko