Hi Nicolin,
On 5/21/26 11:54 PM, Nicolin Chen wrote:
> On Thu, May 21, 2026 at 03:27:17PM +0200, Eric Auger wrote:
>> On 5/21/26 2:26 PM, Shameer Kolothum Thodi wrote:
>>>>> + /* Ignore any invalid address. This may come as part of reset etc. */
>>>>> + if (!address_space_range_is_ram(&address_space_memory, addr, size)) {
>>>> why do you need to test the whole range and not only the start addressa
>>> That was to make it more defensive based on v4 discussion here:
>>> https://lore.kernel.org/qemu-devel/aft%[email protected]/
>>>
>>> Please let me know if there is a better way.
>> Well it is unclear to me. You want to make sure the GPA was fully set
>> through the H and L regs. To me that's enough. As far as I understand
>> Nicolin's reply, the kernel checks the rest. But please sync with Jason
>> or Nicolin
> Yes. Kernel checks if the range is in the stage-2 page table, i.e.,
> mapped GPAs. One caveat: mapped GPA doesn't guarantee it's is_ram.
>
> So, what if the GPA is in the IO space (PCI BAR) or reserved space
> (firmware)?
>
> AFAIK, kernel doesn't have a way to know. So, it's VMM's job to do
> so.
would it jeopardize the host integrity or would it just break the
misbehaving guest. If the latest I am not sure this is critical to
check. We are not checking either with regular SMMU cmd queues
Thanks
Eric
>
> Nicolin
>
