Re: [PATCH 1/6] firmware/smccc: Call arch-specific hook on discovering KVM services

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Will Deacon <will@kernel.org> writes:

> From: Marc Zyngier <maz@kernel.org>
>
> arm64 will soon require its own callback to initialise services
> that are only available on this architecture. Introduce a hook
> that can be overloaded by the architecture.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/arm/include/asm/hypervisor.h   | 2 ++
>  arch/arm64/include/asm/hypervisor.h | 4 ++++
>  drivers/firmware/smccc/kvm_guest.c  | 2 ++
>  3 files changed, 8 insertions(+)
>
> diff --git a/arch/arm/include/asm/hypervisor.h b/arch/arm/include/asm/hypervisor.h
> index bd61502b9715..8a648e506540 100644
> --- a/arch/arm/include/asm/hypervisor.h
> +++ b/arch/arm/include/asm/hypervisor.h
> @@ -7,4 +7,6 @@
>  void kvm_init_hyp_services(void);
>  bool kvm_arm_hyp_service_available(u32 func_id);
>  
> +static inline void kvm_arch_init_hyp_services(void) { };
> +
>  #endif
> diff --git a/arch/arm64/include/asm/hypervisor.h b/arch/arm64/include/asm/hypervisor.h
> index 0ae427f352c8..8cab2ab535b7 100644
> --- a/arch/arm64/include/asm/hypervisor.h
> +++ b/arch/arm64/include/asm/hypervisor.h
> @@ -7,4 +7,8 @@
>  void kvm_init_hyp_services(void);
>  bool kvm_arm_hyp_service_available(u32 func_id);
>  
> +static inline void kvm_arch_init_hyp_services(void)
> +{
> +};
> +
>  #endif
> diff --git a/drivers/firmware/smccc/kvm_guest.c b/drivers/firmware/smccc/kvm_guest.c
> index 89a68e7eeaa6..f3319be20b36 100644
> --- a/drivers/firmware/smccc/kvm_guest.c
> +++ b/drivers/firmware/smccc/kvm_guest.c
> @@ -39,6 +39,8 @@ void __init kvm_init_hyp_services(void)
>  
>  	pr_info("hypervisor services detected (0x%08lx 0x%08lx 0x%08lx 0x%08lx)\n",
>  		 res.a3, res.a2, res.a1, res.a0);
> +
> +	kvm_arch_init_hyp_services();
>  }
>

That is a bit late to detect RMM? One of the requirements is to
figure out the pgprot_t flags for early_ioremap so that "earlycon" will
work (by mapping the address as shared alias). To do that we need to
make an RSI call to detect PROT_NS_SHARED mask as below. 

	if (rsi_get_realm_config(&config))
		return;
	prot_ns_shared = BIT(config.ipa_bits - 1);

-aneesh