mbox series

[RFC,v1,0/2] KVM: arm64: Making BT Field in ID_AA64PFR1_EL1 writable

Message ID 20240612023553.127813-1-shahuang@redhat.com
Headers show
Series KVM: arm64: Making BT Field in ID_AA64PFR1_EL1 writable | expand

Message

Shaoqin Huang June 12, 2024, 2:35 a.m. UTC 
Hi guys,

I'm trying to enable migration from MtCollins(Ampere Altra, ARMv8.2+) to
AmpereOne(AmpereOne, ARMv8.6+), the migration always fails when migration from
MtCollins to AmpereOne due to some register fields differing between the
two machines.

In this patch series, we try to make more register fields writable like
ID_AA64PFR1_EL1.BT. This is first step towards making the migration possible.
Some other hurdles need to be overcome. This is not sufficient to make the
migration successful from MtCollins to AmpereOne.

Shaoqin Huang (2):
  KVM: arm64: Allow BT field in ID_AA64PFR1_EL1 writable
  KVM: selftests: aarch64: Add writable test for ID_AA64PFR1_EL1

 arch/arm64/kvm/sys_regs.c                         | 2 +-
 tools/testing/selftests/kvm/aarch64/set_id_regs.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

Comments

Shaoqin Huang June 17, 2024, 12:29 p.m. UTC | #1 
Hi Marc,

On 6/13/24 16:42, Marc Zyngier wrote:
> On Thu, 13 Jun 2024 09:31:45 +0100,
> Shaoqin Huang <shahuang@redhat.com> wrote:
>>
>> If we don't care about the FEAT_CNTSC right now. Could I fix the
>> compile issue and respin this again without the background of enabling
>> migration between MtCollins and AmpereOne, and just keep the
>> information of the different BT field between different machine?
> 
> As I said, I think this patch is valuable. But maybe you should
> consider tackling the full register, rather than only addressing a
> single field.

Yes, it would be better to tackling the full register. I will put more 
time on other fields in the register and try to making more field to be 
writable. But currently I just respin the series with deleting the 
machine specific information and fixing the compilation issue.

Thanks,
Shaoqin

> 
> Thanks,
> 
> 	M.
>