[PATCH 1/3] proc/vmcore: Do not map unaccepted memory

[David Hildenbrand]

On 11.09.23 11:27, Kirill A. Shutemov wrote:
> On Mon, Sep 11, 2023 at 10:42:51AM +0200, David Hildenbrand wrote:
>> On 11.09.23 10:41, Kirill A. Shutemov wrote:
>>> On Mon, Sep 11, 2023 at 10:03:36AM +0200, David Hildenbrand wrote:
>>>> On 06.09.23 09:39, Adrian Hunter wrote:
>>>>> Support for unaccepted memory was added recently, refer commit
>>>>> dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby
>>>>> a virtual machine may need to accept memory before it can be used.
>>>>>
>>>>> Do not map unaccepted memory because it can cause the guest to fail.
>>>>>
>>>>> For /proc/vmcore, which is read-only, this means a read or mmap of
>>>>> unaccepted memory will return zeros.
>>>>
>>>> Does a second (kdump) kernel that exposes /proc/vmcore reliably get access
>>>> to the information whether memory of the first kernel is unaccepted (IOW,
>>>> not its memory, but the memory of the first kernel it is supposed to expose
>>>> via /proc/vmcore)?
>>>
>>> There are few patches in my queue to few related issue, but generally,
>>> yes, the information is available to the target kernel via EFI
>>> configuration table.
>>
>> I assume that table provided by the first kernel, and not read directly from
>> HW, correct?
> 
> The table is constructed by the EFI stub in the first kernel based on EFI
> memory map.
> 

Okay, should work then once that's done by the first kernel.

Maybe include this patch in your series?

-- 
Cheers,

David / dhildenb