Re: [PATCH v8 08/46] KVM: Provide generic interface for checking memory private/shared status

[Suzuki K Poulose]

On 19/06/2026 09:21, Fuad Tabba wrote:
> On Fri, 19 Jun 2026 at 09:19, Fuad Tabba <tabba@xxxxxxxxxx> wrote:
> > On Fri, 19 Jun 2026 at 01:31, Ackerley Tng via B4 Relay
> > <devnull+ackerleytng.google.com@xxxxxxxxxx> wrote:
> > > From: Sean Christopherson <seanjc@xxxxxxxxxx>
> > >
> > > Introduce a generic kvm_mem_is_private() interface using a static call to
> > > determine if a GFN is private. This allows the implementation for checking
> > > a GFN's private/shared status to be set at runtime.
> > >
> > > In preparation for choosing implementations between a guest_memfd lookup
> > > and the existing VM attribute lookup, rename the existing
> > > VM-attribute-based check to kvm_vm_mem_is_private to emphasize that it
> > > looks up VM attributes.
> > >
> > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > (SoB fix plz)
> >
> > Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
> >
> > Cheers,
> > /fuad
> > > ---
> > >   include/linux/kvm_host.h | 12 +++++++++++-
> > >   virt/kvm/kvm_main.c      | 15 +++++++++++++++
> > >   2 files changed, 26 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > > index eb26d4ea8945a..3915da2a61778 100644
> > > --- a/include/linux/kvm_host.h
> > > +++ b/include/linux/kvm_host.h
> > > @@ -2546,7 +2546,7 @@ bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm,
> > >   bool kvm_arch_post_set_memory_attributes(struct kvm *kvm,
> > >                                           struct kvm_gfn_range *range);
> > >
> > > -static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
> > > +static inline bool kvm_vm_mem_is_private(struct kvm *kvm, gfn_t gfn)
>
> Should have read the Sashiko review first, but where is this used?
> It's not used at all in this series...

See below:

> /fuad
>
> > >   {
> > >          return kvm_get_vm_memory_attributes(kvm, gfn) & KVM_MEMORY_ATTRIBUTE_PRIVATE;
> > >   }
> > > @@ -2557,6 +2557,16 @@ static inline bool kvm_mem_range_is_private(struct kvm *kvm, gfn_t start,
> > >                                                    KVM_MEMORY_ATTRIBUTE_PRIVATE,
> > >                                                    KVM_MEMORY_ATTRIBUTE_PRIVATE);
> > >   }
> > > +#endif  /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */
> > > +
> > > +#ifdef kvm_arch_has_private_mem
> > > +typedef bool (kvm_mem_is_private_t)(struct kvm *kvm, gfn_t gfn);
> > > +DECLARE_STATIC_CALL(__kvm_mem_is_private, kvm_mem_is_private_t);
> > > +
> > > +static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
> > > +{
> > > +       return static_call(__kvm_mem_is_private)(kvm, gfn);
> > > +}
> > >   #else
> > >   static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
> > >   {
> > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > > index 6669f1477013c..8b238e461b854 100644
> > > --- a/virt/kvm/kvm_main.c
> > > +++ b/virt/kvm/kvm_main.c
> > > @@ -2627,6 +2627,20 @@ static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm,
> > >   }
> > >   #endif /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */
> > >
> > > +#ifdef kvm_arch_has_private_mem
> > > +DEFINE_STATIC_CALL_RET0(__kvm_mem_is_private, kvm_mem_is_private_t);
> > > +EXPORT_STATIC_CALL_GPL(__kvm_mem_is_private);
> > > +
> > > +static void kvm_init_memory_attributes(void)
> > > +{
> > > +#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES
> > > +       static_call_update(__kvm_mem_is_private, kvm_vm_mem_is_private);
> > > +#endif
> > > +}


Here ^^ as the static call update ?


Suzuki