Hi David,
On Wed, 21 May 2025 at 09:05, David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxx>
> > ---
> > 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?
We don't reject, but I don't think we need to. A user can create a
guest_memfd that's private in arm64, it would just be useless.
Cheers,
/fuad
> --
> Cheers,
>
> David / dhildenb
>
