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

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 19/06/2026 09:21, Fuad Tabba wrote:
> On Fri, 19 Jun 2026 at 09:19, Fuad Tabba <tabba@google.com> wrote:
>>
>> On Fri, 19 Jun 2026 at 01:31, Ackerley Tng via B4 Relay
>> <devnull+ackerleytng.google.com@kernel.org> wrote:
>>>
>>> From: Sean Christopherson <seanjc@google.com>
>>>
>>> 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@google.com>
>>
>> (SoB fix plz)
>>
>> Reviewed-by: Fuad Tabba <tabba@google.com>
>>
>> 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