Re: [PATCH] mem/x86: add processor address space check for VM memory

[Ani Sinha]

On Mon, 18 Sept, 2023, 3:39 pm David Hildenbrand, <david@redhat.com> wrote:

On 18.09.23 12:07, Ani Sinha wrote:
>
>
> On Mon, 18 Sept, 2023, 3:03 pm David Hildenbrand, <david@redhat.com
> <mailto:david@redhat.com>> wrote:
>
>      >>
>      >>>> /*
>      >>>> * The 64bit pci hole starts after "above 4G RAM" and
>      >>>> * potentially the space reserved for memory hotplug.
>      >>>> */
>      >>>>
>      >>>> There is the
>      >>>>    ROUND_UP(hole64_start, 1 * GiB);
>      >>>> in there that is not really required for the !hole64 case. It
>      >>>> shouldn't matter much in practice I think (besides an aligned
>     value
>      >>>> showing up in the error message).
>      >>>>
>      >>>> We could factor out most of that calculation into a
>      >>>> separate function, skipping that alignment to make that
>      >>>> clearer.
>      >>> Yeah this whole memory segmentation is quite complicated and
>     might benefit from a qemu doc or a refactoring.
>      >>
>      >> Absolutely. Do you have time to work on that (including the
>     updated fix?).
>      >
>      > Other than the fix you proposed I am not sure if we need to fix
>     anything else atm. Seems physical address space bound checks are
>     already in place.
>      > Re: doc, maybe. I will add it to my TODO list.
>
>     Will you send a proper patch, ideally not using pc_pci_hole64_start()
>     but instead the same logic without the final alignment to 1 GiB?
>
>
> I'll send. No problem. Could you answer my other question please ?

Sorry, which one did I miss

Ok hopefully my last question. I am still confused on something. Does the above mean that the hole64 will actually start from an address that is beyond maxram? Like basically if you added all of ram_below_4G, ram_above_4G, hot plug_mem and pci_hole64 then can it exceed maxram? I think it will. Does this not an issue?

--
Cheers,

David / dhildenb