Date:   Tue, 14 Jul 2020 20:19:59 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Wei Liu <wei.liu@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Jian Cai <caij2003@...il.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: Re: [PATCH v2] x86/entry: Fix vectors to IDTENTRY_SYSVEC for CONFIG_HYPERV

On Tue, Jul 14, 2020 at 7:46 PM Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
>
> On Tue, Jul 14, 2020 at 4:11 AM Sedat Dilek <sedat.dilek@...il.com> wrote:
> >
> > When using Clang's Integrated Assembler (LLVM_IAS=1) we fell over
> > ClangBuiltLinux (CBL) issue #1043 where Jian Cai provided a patch.
> >
> > With Jian's patch applied another issue raised up when CONFIG_HYPERV=m.
> >
> > It turned out that the conversion of vectors to IDTENTRY_SYSVEC in
> > case of CONFIG_HYPERV was incomplete and fails with a build error:
> >
> > <instantiation>:9:6: error: expected absolute expression
> >  .if HYPERVISOR_REENLIGHTENMENT_VECTOR == 3
> >      ^
> > <instantiation>:1:1: note: while in macro instantiation
> > idtentry HYPERVISOR_REENLIGHTENMENT_VECTOR asm_sysvec_hyperv_reenlightenment sysvec_hyperv_reenlightenment has_error_code=0
> > ^
> > ./arch/x86/include/asm/idtentry.h:627:1: note: while in macro instantiation
> > idtentry_sysvec HYPERVISOR_REENLIGHTENMENT_VECTOR sysvec_hyperv_reenlightenment;
> > ^
> > <instantiation>:9:6: error: expected absolute expression
> >  .if HYPERVISOR_STIMER0_VECTOR == 3
> >      ^
> > <instantiation>:1:1: note: while in macro instantiation
> > idtentry HYPERVISOR_STIMER0_VECTOR asm_sysvec_hyperv_stimer0 sysvec_hyperv_stimer0 has_error_code=0
> > ^
> > ./arch/x86/include/asm/idtentry.h:628:1: note: while in macro instantiation
> > idtentry_sysvec HYPERVISOR_STIMER0_VECTOR sysvec_hyperv_stimer0;
> >
> > I and Nathan double-checked the hyperv(isor) vectors:
> >
> > $ rg --no-heading "HYPERVISOR_REENLIGHTENMENT_VECTOR|HYPERVISOR_STIMER0_VECTOR"
> > $ rg --no-heading "HYPERV_REENLIGHTENMENT_VECTOR|HYPERV_STIMER0_VECTOR"
> >
> > Fix these typos in arch/x86/include/asm/idtentry.h:
> >
> > HYPERVISOR_REENLIGHTENMENT_VECTOR -> HYPERV_REENLIGHTENMENT_VECTOR
> > HYPERVISOR_STIMER0_VECTOR         -> HYPERV_STIMER0_VECTOR
> >
> > For more details see CBL issue #1088.
> >
> > With both fixes applied I was able to build/assemble with a snapshot
> > version of LLVM/Clang from Debian/experimental.
> >
> > NOTE: My patch is independent from Jian's patch and should be applied separately.
>
> Hi Sedat,
> Thanks for the patch!  Nice job finding the fix.
>
> I would like to see a v3 with the commit message trimmed a bit.  In
> particular, you mention that Jian's patch is unrelated.  In that case,
> please don't mention it in the commit message, drop the link to issue
> #1043, and drop the lore link.  I think if the commit was just simply:
>
> ```
> x86/entry: Fix vectors to IDTENTRY_SYSVEC for CONFIG_HYPERV
>
> When assembling with Clang via `make LLVM_IAS=1`, we observe the
> following error:
> <instantiation>:9:6: error: expected absolute expression
> <rest of the diagnostic>
>
> This is caused by typos in arch/x86/include/asm/idtentry.h:
>
> HYPERVISOR_REENLIGHTENMENT_VECTOR -> HYPERV_REENLIGHTENMENT_VECTOR
> HYPERVISOR_STIMER0_VECTOR         -> HYPERV_STIMER0_VECTOR
> ```
> Then the tags you have below minus the unrelated ones.
>
> >
> > Cc: Jian Cai <caij2003@...il.com>
> > Cc: clang-built-linux@...glegroups.com
> > Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
> > Reviewed-by: Wei Liu <wei.liu@...nel.org>
> > Fixes: a16be368dd3f ("x86/entry: Convert various hypervisor vectors to IDTENTRY_SYSVEC")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1043
> > Link: https://lore.kernel.org/patchwork/patch/1272115/
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1088
> > Signed-off-by: Sedat Dilek <sedat.dilek@...il.com>
> > ---
>
> Otherwise you can put some additional info here "below the fold."  It
> doesn't hurt to say "I also need Jian's patch to completely build with
> LLVM_IAS=1" but I don't think that should be in the message that gets
> committed per se.  Sorry to be a pedant about this.  With those
> changes, I'd be happy to sign off on the patch.
>

Yeah, that sounds like good compromise.

Without Jian's fix/patch we did not found the issue.
I wanted to respect this.

I will send out a v3 soonish.

- Sedat -

> > Changes v1->v2:
> > - Add Wei Liu's Reviewed-by
> > - Add note to clarify my patch is independent from Jian's patch
> > - Add link to latest version of Jian's patch
> >
> >  arch/x86/include/asm/idtentry.h | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
> > index eeac6dc2adaa..d79541bfc36f 100644
> > --- a/arch/x86/include/asm/idtentry.h
> > +++ b/arch/x86/include/asm/idtentry.h
> > @@ -626,8 +626,8 @@ DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_NESTED_VECTOR,  sysvec_kvm_posted_intr_nested
> >
> >  #if IS_ENABLED(CONFIG_HYPERV)
> >  DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR,    sysvec_hyperv_callback);
> > -DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_REENLIGHTENMENT_VECTOR,     sysvec_hyperv_reenlightenment);
> > -DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_STIMER0_VECTOR,     sysvec_hyperv_stimer0);
> > +DECLARE_IDTENTRY_SYSVEC(HYPERV_REENLIGHTENMENT_VECTOR, sysvec_hyperv_reenlightenment);
> > +DECLARE_IDTENTRY_SYSVEC(HYPERV_STIMER0_VECTOR, sysvec_hyperv_stimer0);
> >  #endif
> >
> >  #if IS_ENABLED(CONFIG_ACRN_GUEST)
> > --
>
> --
> Thanks,
> ~Nick Desaulniers

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