Re: [PATCH v6 05/21] arm64: Initialise as nVHE before switching to VHE

[Hector Martin 'marcan']

On 01/02/2021 20.56, Marc Zyngier wrote:
> As we are aiming to be able to control whether we enable VHE or
> not, let's always drop down to EL1 first, and only then upgrade
> to VHE if at all possible.
>
> This means that if the kernel is booted at EL2, we always start
> with a nVHE init, drop to EL1 to initialise the the kernel, and
> only then upgrade the kernel EL to EL2 if possible (the process
> is obviously shortened for secondary CPUs).

Unfortunately, this is going to break on Apple SoCs, where it turns out 
HCR_EL2.E2H is hard-wired to 1 - there is no nVHE mode. :(

>>> mrs(HCR_EL2) & (1<<34)
0x400000000
>>> msr(HCR_EL2, mrs(HCR_EL2) & ~(1<<34))
>>> mrs(HCR_EL2) & (1<<34)
0x400000000

--
Hector Martin "marcan" (marcan@xxxxxxxxx)
Public Key: https://mrcn.st/pub