From mboxrd@z Thu Jan  1 00:00:00 1970
From: christoffer.dall@arm.com (Christoffer Dall)
Date: Tue, 6 Nov 2018 08:53:53 +0100
Subject: [PATCH 2/4] KVM: arm64: Allow implementations to be confined to
 using VHE
In-Reply-To: <20181105143617.120602-3-marc.zyngier@arm.com>
References: <20181105143617.120602-1-marc.zyngier@arm.com>
 <20181105143617.120602-3-marc.zyngier@arm.com>
Message-ID: <20181106075353.GF12057@e113682-lin.lund.arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Nov 05, 2018 at 02:36:14PM +0000, Marc Zyngier wrote:
> Some implementations may be forced to use VHE to work around HW
> errata, for example. Let's introduce a helper that checks for
> these cases.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  arch/arm/include/asm/kvm_host.h   | 1 +
>  arch/arm64/include/asm/kvm_host.h | 6 ++++++
>  virt/kvm/arm/arm.c                | 5 +++++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index c3469729f40c..0f2f782548cb 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -286,6 +286,7 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>  struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
>  
>  static inline bool kvm_arch_sve_requires_vhe(void) { return false; }
> +static inline bool kvm_arch_impl_requires_vhe(void) { return false; }
>  static inline void kvm_arch_hardware_unsetup(void) {}
>  static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index ca1714148400..7d6e974d024a 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -432,6 +432,12 @@ static inline bool kvm_arch_sve_requires_vhe(void)
>  	return system_supports_sve();
>  }
>  
> +static inline bool kvm_arch_impl_requires_vhe(void)
> +{
> +	/* Some implementations have defects that confine them to VHE */
> +	return false;
> +}
> +
>  static inline void kvm_arch_hardware_unsetup(void) {}
>  static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 66de2efddfca..bc90a1cdd27f 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -1647,6 +1647,11 @@ int kvm_arch_init(void *opaque)
>  			kvm_pr_unimpl("SVE system without VHE unsupported.  Broken cpu?");
>  			return -ENODEV;
>  		}
> +
> +		if (kvm_arch_impl_requires_vhe()) {
> +			kvm_pr_unimpl("CPU requiring VHE in non-VHE mode");
> +			return -ENODEV;
> +		}

So as per my previous comment, I'd prefer this function to only issue a
single call, and have the function in kvm_host.h check for all the
conditions, do the printing, etc.

Thoughts?


Thanks,

    Christoffer

>  	}
>  
>  	for_each_online_cpu(cpu) {
> -- 
> 2.19.1
>