[PATCH][for-stable-v5.11]] arm64: Unconditionally set virtual cpu id registers

[Vladimir Murzin]

On 3/16/21 11:31 AM, Greg KH wrote:
> On Tue, Mar 16, 2021 at 11:25:00AM +0000, Vladimir Murzin wrote:
>> Commit 78869f0f0552 ("arm64: Extract parts of el2_setup into a macro")
>> reorganized el2 setup in such way that virtual cpu id registers set
>> only in nVHE, yet they used (and need) to be set irrespective VHE
>> support. Lack of setup causes 32-bit guest stop booting due to MIDR
>> stay undefined.
>>
>> Fixes: 78869f0f0552 ("arm64: Extract parts of el2_setup into a macro")
>> Signed-off-by: Vladimir Murzin <vladimir.murzin at arm.com>
>> ---
>>
>> There is no upstream fix since issue went away due to code there has
>> been reworked in 5.12: nVHE comes first, so virtual cpu id register
>> are always set.
>>
>> Maintainers, please, Ack.
> 
> Why not just use the "rework" patch instead that fixes this issue?> 
> 
> that's always preferred instead of one-off patches.

That's moderate size patch series [1] which brings new functionality, but
more importantly move boot flow upside down, where we first boot nVHE and
then switch to VHE if supported. I think that a lot of change to carry in
stable compare to proposed fix.

[1] https://lore.kernel.org/kvmarm/20210208095732.3267263-2-maz@kernel.org/

Cheers
Vladimir

> 
> thanks,
> 
> greg k-h
>