Re: [PATCH v9 14/17] KVM: arm64: Enable mapping guest_memfd in arm64

[David Hildenbrand <david@redhat.com>]

On 13.05.25 18:34, Fuad Tabba wrote:
> Enable mapping guest_memfd in arm64. For now, it applies to all
> VMs in arm64 that use guest_memfd. In the future, new VM types
> can restrict this via kvm_arch_gmem_supports_shared_mem().
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
>   arch/arm64/include/asm/kvm_host.h | 10 ++++++++++
>   arch/arm64/kvm/Kconfig            |  1 +
>   2 files changed, 11 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 08ba91e6fb03..2514779f5131 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -1593,4 +1593,14 @@ static inline bool kvm_arch_has_irq_bypass(void)
>   	return true;
>   }
>   
> +static inline bool kvm_arch_supports_gmem(struct kvm *kvm)
> +{
> +	return IS_ENABLED(CONFIG_KVM_GMEM);
> +}
> +
> +static inline bool kvm_arch_vm_supports_gmem_shared_mem(struct kvm *kvm)
> +{
> +	return IS_ENABLED(CONFIG_KVM_GMEM_SHARED_MEM);
> +}
> +
>   #endif /* __ARM64_KVM_HOST_H__ */
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 096e45acadb2..8c1e1964b46a 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -38,6 +38,7 @@ menuconfig KVM
>   	select HAVE_KVM_VCPU_RUN_PID_CHANGE
>   	select SCHED_INFO
>   	select GUEST_PERF_EVENTS if PERF_EVENTS
> +	select KVM_GMEM_SHARED_MEM
>   	help
>   	  Support hosting virtualized guest machines.
>   

Do we have to reject somewhere if we are given a guest_memfd that was 
*not* created using the SHARED flag? Or will existing checks already 
reject that?

-- 
Cheers,

David / dhildenb