Message-ID: <CAKwvOdk3WSMhMxxaWfFeWYkR=xYgwrREckS+X5Yg5QeC48UVrg@mail.gmail.com>
Date:   Tue, 14 Jul 2020 10:46:24 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Sedat Dilek <sedat.dilek@...il.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 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.

> 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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