[PATCH 1/2] KVM: arm64: Fix hvhe/nvhe early alias parsing

[Will Deacon]

Hey Oliver,

On Wed, May 01, 2024 at 05:44:57PM +0000, Oliver Upton wrote:
> On Wed, May 01, 2024 at 05:33:59PM +0100, Will Deacon wrote:
> > Booting a kernel with "arm64_sw.hvhe=1 kvm-arm.mode=nvhe" on the
> > command-line results in KVM initialising using hVHE, whereas one might
> > expect the latter option to override the former.
> > 
> > Fix this by adding "arm64_sw.hvhe=0" to the alias expansion for
> > "kvm-arm.mode=nvhe".
> 
> Hmm, I wonder if it'd be better to just evaluate the sanitised VH field
> in hvhe_possible(). Otherwise I worry about keeping aliases in sync when
> new command line options come along.
> 
> This is similar to what we had before commit 35876f35f482 ("arm64:
> cpufeature: Add helper to test for CPU feature overrides") w/ the added
> use of the sanitised reg.
> 
> Thoughts?

I think that goes wonky when you have the arguments the other way around:

	"kvm-arm.mode=nvhe arm64_sw.hvhe=1"

would end up using nVHE.

Will