Re: HCR_EL2 GET_ONE_REG value difference

[Marc Zyngier <maz@kernel.org>]

On Fri, 10 Oct 2025 09:30:12 +0100,
Jan Kotas <jank@cadence.com> wrote:
> 
> Hello,
> 
> During NV debugging I noticed a difference in HCR_EL2 value.
> 
> The value I get from accessing this register, using KVM_GET_ONE_REG:
> 0x30480000000

These bits are API, APK, E2H, RW.

When did you access this? After the vcpu has run? Before it has run?
What NV configuration did you use?

>
> However, X1 value after executing mrs x1, hcr_el2 in guest:
> 0x100030080000000

You have ATA, API, APK, RW. Is that the *only* thing that has run in
your guest?

> I access both of these at the same place.

"at the same place"? What do you mean? One is accessed from host
userspace, and the other from the guest. How can that be the same
place?

> I get the list of available registers from KVM_GET_REG_LIST.
> 
> I double checked my encoding, and it seems to be correct.
> HCR_EL2 3, 4, 1, 1, 0
> 
> I can check other registers, but I first wanted to check, if this expected?
> Is there something I’m missing, when accessing emulated registers?

Could you please start by clarifying what you are doing?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.