linux-kernel - Re: [PATCH v3 08/18] KVM: arm64: Add {get,put}_pkvm_hyp

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Message-ID: <CA+EHjTxd5euMqYrq510kgqvON1JdGmjhE4ROFuMwTR1pgwLD9w@mail.gmail.com>
Date: Tue, 17 Dec 2024 08:48:17 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Quentin Perret <qperret@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Vincent Donnefort <vdonnefort@...gle.com>, 
	Sebastian Ene <sebastianene@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/18] KVM: arm64: Add {get,put}_pkvm_hyp_vm() helpers

On Mon, 16 Dec 2024 at 17:58, Quentin Perret <qperret@...gle.com> wrote:
>
> In preparation for accessing pkvm_hyp_vm structures at EL2 in a context
> where we can't always expect a vCPU to be loaded (e.g. MMU notifiers),
> introduce get/put helpers to get temporary references to hyp VMs from
> any context.
>
> Signed-off-by: Quentin Perret <qperret@...gle.com>

Reviewed-by: Fuad Tabba <tabba@...gle.com>

Cheers,
/fuad

> ---
>  arch/arm64/kvm/hyp/include/nvhe/pkvm.h |  3 +++
>  arch/arm64/kvm/hyp/nvhe/pkvm.c         | 20 ++++++++++++++++++++
>  2 files changed, 23 insertions(+)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> index 24a9a8330d19..f361d8b91930 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> @@ -70,4 +70,7 @@ struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
>                                          unsigned int vcpu_idx);
>  void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu);
>
> +struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle);
> +void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm);
> +
>  #endif /* __ARM64_KVM_NVHE_PKVM_H__ */
> diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> index 071993c16de8..d46a02e24e4a 100644
> --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
> +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> @@ -327,6 +327,26 @@ void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
>         hyp_spin_unlock(&vm_table_lock);
>  }
>
> +struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle)
> +{
> +       struct pkvm_hyp_vm *hyp_vm;
> +
> +       hyp_spin_lock(&vm_table_lock);
> +       hyp_vm = get_vm_by_handle(handle);
> +       if (hyp_vm)
> +               hyp_page_ref_inc(hyp_virt_to_page(hyp_vm));
> +       hyp_spin_unlock(&vm_table_lock);
> +
> +       return hyp_vm;
> +}
> +
> +void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm)
> +{
> +       hyp_spin_lock(&vm_table_lock);
> +       hyp_page_ref_dec(hyp_virt_to_page(hyp_vm));
> +       hyp_spin_unlock(&vm_table_lock);
> +}
> +
>  static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struct kvm *host_kvm)
>  {
>         struct kvm *kvm = &hyp_vm->kvm;
> --
> 2.47.1.613.gc27f4b7a9f-goog
>