[PATCH 3/3] KVM: arm64: timer: Consolidate NV configuration of virtual timers
Oliver Upton
oliver.upton at linux.dev
Thu Jan 30 13:41:04 PST 2025
> +void kvm_timer_vcpu_nv_init(struct kvm_vcpu *vcpu)
> +{
> + /*
> + * A vcpu running at EL2 is in charge of the offset applied to
> + * the virtual timer, so use the physical VM offset, and point
> + * the vcpu offset to CNTVOFF_EL2.
> + *
> + * The virtual offset behaviour is "interesting", as it always
> + * applies when HCR_EL2.E2H==0, but only when accessed from EL1 when
> + * HCR_EL2.E2H==1. Apply it to the HV timer when E2H==0.
> + */
I'm definitely being pedantic, but all the talk of an HV timer when
E2H==0 isn't sitting well with me. Since a programmable E2H has gone
out the window there isn't such thing as an HV timer when E2H==0, as
FEAT_VHE isn't implemented for the VM.
And along those lines, accesses to CNTHV_*_EL2 registers should undef
when FEAT_VHE isn't implemented for the VM but I don't think we have any
enforcement of that.
--
Thanks,
Oliver
More information about the linux-arm-kernel
mailing list