[RFC PATCH v2 04/38] KVM: arm/arm64: Check if nested virtualization is in use

Christoffer Dall
2017-07-30T19:59:38Z

On Tue, Jul 18, 2017 at 11:58:30AM -0500, Jintack Lim wrote:
> Nested virtualizaion is in use only if all three conditions are met:
> - The architecture supports nested virtualization.
> - The kernel parameter is set.
> - The userspace uses nested virtualiztion feature.
>
> Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
> ---
> arch/arm/include/asm/kvm_host.h | 11 +++++++++++
> arch/arm64/include/asm/kvm_host.h | 2 ++
> arch/arm64/kvm/nested.c | 17 +++++++++++++++++
> virt/kvm/arm/arm.c | 4 ++++
> 4 files changed, 34 insertions(+)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 00b0f97..7e9e6c8 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -303,4 +303,15 @@ static inline int __init kvmarm_nested_cfg(char *buf)
> {
> return 0;
> }
> +
> +static inline int init_nested_virt(void)
> +{
> + return 0;
> +}
> +
> +static inline bool nested_virt_in_use(struct kvm_vcpu *vcpu)
> +{
> + return false;
> +}
> +
> #endif /* __ARM_KVM_HOST_H__ */
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 6df0c7c..86d4b6c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -387,5 +387,7 @@ static inline void __cpu_init_stage2(void)
> }
>
> int __init kvmarm_nested_cfg(char *buf);
> +int init_nested_virt(void);
> +bool nested_virt_in_use(struct kvm_vcpu *vcpu);
>
> #endif /* __ARM64_KVM_HOST_H__ */
> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
> index 79f38da..9a05c76 100644
> --- a/arch/arm64/kvm/nested.c
> +++ b/arch/arm64/kvm/nested.c
> @@ -24,3 +24,20 @@ int __init kvmarm_nested_cfg(char *buf)
> {
> return strtobool(buf, &nested_param);
> }
> +
> +int init_nested_virt(void)
> +{
> + if (nested_param && cpus_have_const_cap(ARM64_HAS_NESTED_VIRT))
> + kvm_info("Nested virtualization is supported\n");
> +
> + return 0;
> +}
> +
> +bool nested_virt_in_use(struct kvm_vcpu *vcpu)
> +{
> + if (nested_param && cpus_have_const_cap(ARM64_HAS_NESTED_VIRT)
> + && test_bit(KVM_ARM_VCPU_NESTED_VIRT, vcpu->arch.features))
> + return true;
> +
> + return false;
> +}

after reading through a lot of your patches, I feel like vm_has_el2()
would be a more elegant name, but it's not a strict requirement to
change it.

> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 1c1c772..36aae3a 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -1478,6 +1478,10 @@ int kvm_arch_init(void *opaque)
> if (err)
> goto out_err;
>
> + err = init_nested_virt();
> + if (err)
> + return err;
> +
> err = init_subsystems();
> if (err)
> goto out_hyp;
> --
> 1.9.1
>

Thanks,
-Christoffer