Re: [PATCH v8 8/8] KVM: Enable and expose KVM_MEM_PRIVATE

[Chao Peng]

On Tue, Oct 04, 2022 at 05:55:28PM +0300, Jarkko Sakkinen wrote:
> On Thu, Sep 15, 2022 at 10:29:13PM +0800, Chao Peng wrote:
> > Expose KVM_MEM_PRIVATE and memslot fields private_fd/offset to
> > userspace. KVM will register/unregister private memslot to fd-based
> > memory backing store and response to invalidation event from
> > inaccessible_notifier to zap the existing memory mappings in the
> > secondary page table.
> > 
> > Whether KVM_MEM_PRIVATE is actually exposed to userspace is determined
> > by architecture code which can turn on it by overriding the default
> > kvm_arch_has_private_mem().
> > 
> > A 'kvm' reference is added in memslot structure since in
> > inaccessible_notifier callback we can only obtain a memslot reference
> > but 'kvm' is needed to do the zapping.
> > 
> > Co-developed-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
> > Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
> > Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> 
> ld: arch/x86/../../virt/kvm/kvm_main.o: in function `kvm_free_memslot':
> kvm_main.c:(.text+0x1385): undefined reference to `inaccessible_unregister_notifier'
> ld: arch/x86/../../virt/kvm/kvm_main.o: in function `kvm_set_memslot':
> kvm_main.c:(.text+0x1b86): undefined reference to `inaccessible_register_notifier'
> ld: kvm_main.c:(.text+0x1c85): undefined reference to `inaccessible_unregister_notifier'
> ld: arch/x86/kvm/mmu/mmu.o: in function `kvm_faultin_pfn':
> mmu.c:(.text+0x1e38): undefined reference to `inaccessible_get_pfn'
> ld: arch/x86/kvm/mmu/mmu.o: in function `direct_page_fault':
> mmu.c:(.text+0x67ca): undefined reference to `inaccessible_put_pfn'
> make: *** [Makefile:1169: vmlinux] Error 1
> 
> I attached kernel config for reproduction.
> 
> The problem is that CONFIG_MEMFD_CREATE does not get enabled:
> 
> mm/Makefile:obj-$(CONFIG_MEMFD_CREATE) += memfd.o memfd_inaccessible.o

Thanks for reporting. Yes there is a dependency issue needs to fix.

Chao