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

Hector Martin 'marcan' marcan at marcan.st
Fri Feb 5 07:01:46 EST 2021

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

Hector Martin "marcan" (marcan at marcan.st)
Public Key: https://mrcn.st/pub

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