Re: [BUG net-next] arch/x86/kernel/cpu/bugs.c:2935: "Unpatched return thunk in use. This should not happen!" [STACKTRACE]

Sean Christopherson
2024-04-03T12:48:24Z

On Wed, Apr 03, 2024, Borislav Petkov wrote:
> On Tue, Apr 02, 2024 at 08:38:56AM -0500, Michael Roth wrote:
> > On Tue, Apr 02, 2024 at 12:15:49PM +0200, bp@kernel.org wrote:
> > I can also trigger using one of the more basic KVM selftests:
> >
> > make INSTALL_HDR_PATH="$headers_dir" headers_install
> > make -C tools/testing/selftests TARGETS="kvm" EXTRA_CFLAGS="-DDEBUG -I$headers_dir"
> > sudo tools/testing/selftests/kvm/userspace_io_test
>
> Ok, thanks, that helped.
>
> Problem is:
>
> 7f4b5cde2409 ("kvm: Disable objtool frame pointer checking for vmenter.S")
>
> it is disabling checking of the arch/x86/kvm/svm/vmenter.S by objtool
> when CONFIG_FRAME_POINTER=y but that also leads to objtool *not*
> generating .return_sites and the return thunk remains unpatched.
>
> I think we need to say: ignore frame pointer checking but still generate
> .return_sites.

I'm guessing a general solution for OBJECT_FILES_NON_STANDARD is needed, but I
have a series to drop it for vmenter.S.