Re: [PATCH v1 4/4] KVM: arm64: Initialize trap register values in hyp in pKVM

[Oliver Upton <oliver.upton@linux.dev>]

On Mon, Oct 14, 2024 at 11:24:12AM +0100, Fuad Tabba wrote:
> Handle the initialization of trap registers at the hypervisor in
> pKVM, even for non-protected guests. The host is not trusted with
> the values of the trap registers, regardless of the VM type.
> Therefore, when switching between the host and the guests, only
> flush the required bits of the trap registers from the host's
> view that are required for hyp-host communication.

It'd be a bit more precise to just mention that the host is allowed to
configure TWI and TWE still for opportunistic scheduling, as neither
affects the protection of VMs or the hypervisor.

>  	pvm_init_trap_regs(vcpu);
>  	pvm_init_traps_aa64pfr0(vcpu);
>  	pvm_init_traps_aa64pfr1(vcpu);

aside: it'd be great to reorganize all of these traps in terms of the
affected trap register and not the feature register.

But that can happen later.

-- 
Thanks,
Oliver