Re: [PATCH v2 0/3] KVM: arm64: Fix handling of ID_PFR1_EL1.GIC

[Suzuki K Poulose <suzuki.poulose@arm.com>]

Hi Marc

On 30/10/2025 12:27, Marc Zyngier wrote:
> Peter reported[0] that restoring a GICv2 VM fails badly, and correctly
> points out that ID_PFR1_EL1.GIC isn't writable, while its 64bit
> equivalent is. I broke that in 6.12.
> 
> The other thing is that fixing the ID regs at runtime isn't great.
> specially when we could adjust them at the point where the GIC gets
> created.
> 
> This small series aims at fixing these issues. I've only tagged the
> first one as a stable candidate. 

But, all 3 patches have the same Fixes tag, was that intentional ?

Otherwise looks good.

Suzuki


With these fixes, I can happily



> save/restore a GICv2 VM (both 32 and 64bit) on my trusty Synquacer.
> 
> * From v1 [1]:
> 
>    - Make all 32bit ID regs writable
> 
>    - Use official accessors to manipulate ID regs
> 
>    - Rebased on 6.18-rc3
> 
> [0] https://lore.kernel.org/r/CAFEAcA8TpQduexT=8rdRYC=yxm_073COjzgWJAvc26_T+-F5vA@mail.gmail.com
> [3] https://lore.kernel.org/r/20251013083207.518998-1-maz@kernel.org
> 
> Marc Zyngier (3):
>    KVM: arm64: Make all 32bit ID registers fully writable
>    KVM: arm64: Set ID_{AA64PFR0,PFR1}_EL1.GIC when GICv3 is configured
>    KVM: arm64: Limit clearing of ID_{AA64PFR0,PFR1}_EL1.GIC to userspace
>      irqchip
> 
>   arch/arm64/kvm/sys_regs.c       | 71 ++++++++++++++++++---------------
>   arch/arm64/kvm/vgic/vgic-init.c | 14 ++++++-
>   2 files changed, 50 insertions(+), 35 deletions(-)
>