On Wed, Feb 22, 2023, Randy Dunlap wrote:
> modpost reports section mismatch errors/warnings:
> WARNING: modpost: vmlinux.o: section mismatch in reference: svm_hv_hardware_setup (section: .text) -> (unknown) (section: .init.data)
> WARNING: modpost: vmlinux.o: section mismatch in reference: svm_hv_hardware_setup (section: .text) -> (unknown) (section: .init.data)
> WARNING: modpost: vmlinux.o: section mismatch in reference: svm_hv_hardware_setup (section: .text) -> (unknown) (section: .init.data)
>
> Marking svm_hv_hardware_setup() as __init fixes the warnings.
>
> I don't know why this should be needed -- it seems like a compiler
> problem to me since the calling function is marked as __init.
It's not a compiler issue. __initdata is freed after init and so must not be
accessed by __init-less functions.
This as a changelog?
Tag svm_hv_hardware_setup() with __init to fix a modpost warning as the
non-stub implementation accesses __initdata (svm_x86_ops), i.e. would
generate a use-after-free if svm_hv_hardware_setup() were actually invoked
post-init. The helper is only called from svm_hardware_setup(), which is
also __init, i.e. other than the modpost warning, lack of __init is benign.
With that (in case Paolo grabs this directly):
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> This "(unknown) (section: .init.data)" all refer to svm_x86_ops.
>
> Fixes: 1e0c7d40758b ("KVM: SVM: hyper-v: Remote TLB flush for SVM")
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Vineeth Pillai <viremana@xxxxxxxxxxxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> ---
> v2: also make the empty stub function be __init (Vitaly)
>
> arch/x86/kvm/svm/svm_onhyperv.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff -- a/arch/x86/kvm/svm/svm_onhyperv.h b/arch/x86/kvm/svm/svm_onhyperv.h
> --- a/arch/x86/kvm/svm/svm_onhyperv.h
> +++ b/arch/x86/kvm/svm/svm_onhyperv.h
> @@ -30,7 +30,7 @@ static inline void svm_hv_init_vmcb(stru
> hve->hv_enlightenments_control.msr_bitmap = 1;
> }
>
> -static inline void svm_hv_hardware_setup(void)
> +static inline __init void svm_hv_hardware_setup(void)
> {
> if (npt_enabled &&
> ms_hyperv.nested_features & HV_X64_NESTED_ENLIGHTENED_TLB) {
> @@ -84,7 +84,7 @@ static inline void svm_hv_init_vmcb(stru
> {
> }
>
> -static inline void svm_hv_hardware_setup(void)
> +static inline __init void svm_hv_hardware_setup(void)
> {
> }
>
>
