Re: [PATCH] ArmPkg: update InvalidateInstructionCacheRange to flush only to PoU

[Laszlo Ersek <lersek@redhat.com>]

On 01/28/19 11:46, Mark Rutland wrote:
> On Wed, Jan 23, 2019 at 10:54:56AM +0100, Laszlo Ersek wrote:
>> On 01/23/19 10:26, Ard Biesheuvel wrote:
>>> On Wed, 23 Jan 2019 at 10:14, Laszlo Ersek <lersek@redhat.com> wrote:
>>>> On 01/22/19 16:37, Ard Biesheuvel wrote:
>>
>>>>> Is SetUefiImageMemoryAttributes() being
>>>>> called to remap the memory R-X ?
>>>>
>>>> No, it is not; the grub binary in question doesn't have the required
>>>> section alignment (... I hope at least that that's what your question
>>>> refers to):
>>>>
>>>>> ProtectUefiImageCommon - 0x3E6C54C0
>>>>>   - 0x000000013BEEF000 - 0x0000000000030600
>>>>> !!!!!!!!  ProtectUefiImageCommon - Section Alignment(0x200) is
>>>> incorrect  !!!!!!!!
>>>
>>> This is puzzling, given that the exact same binary works on Mustang.
>>
>> And even on the original (unspecified) hardware, the same binary works
>> frequently. My understanding is that there are five VMs executing reboot
>> loops in parallel, on the same host, and 4 out of 5 may hit the issue in
>> a reasonable time period (300 reboots or so).
> 
> Interesting.
> 
> Do you happen to know how many VMID bits the host has? If it has an 8-bit VMID,
> this could be indicative of some problem upon overflow.

I'll let Tan Xiaojun (CC'd) answer this questions.

> Can you point us at the host kernel?

In the report, Tan Xiaojun wrote "4.18.0-48.el8.aarch64"; I guess that
information is mostly useless in an upstream discussion. Unfortunately,
I couldn't reproduce the symptom at all (I know nothing about the
hardware in question), so I can't myself retest with an upstream host
kernel.

Thank you!
Laszlo