linux-kernel - Re: [PATCH] x86/entry: Fix vectors to IDTENTRY_SYSVEC for CONFIG

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Message-ID: <CA+icZUUAyqgJR-qQFMvFAK-SJmUaxdH9EL9VXR0Me+hwJW5qaQ@mail.gmail.com>
Date:   Mon, 13 Jul 2020 17:59:13 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Wei Liu <wei.liu@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        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>,
        linux-kernel@...r.kernel.org,
        Clang-Built-Linux ML <clang-built-linux@...glegroups.com>,
        Jian Cai <caij2003@...il.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: Re: [PATCH] x86/entry: Fix vectors to IDTENTRY_SYSVEC for CONFIG_HYPERV

On Mon, Jul 13, 2020 at 1:13 PM Wei Liu <wei.liu@...nel.org> wrote:
>
> On Mon, Jul 13, 2020 at 01:10:50AM +0200, Sedat Dilek wrote:
> > When using Clang's Integrated Assembler (LLVM_IAS=1) we fell over
> > ClangBuiltLinux (CBL) issue #1043 where Jian Cai provided a fix.
> >
> > With Jian's fix 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;
>
> Hmm... Interesting. GCC never complained. Guests are perhaps broken in a
> rather subtle way.
>
> >
> > 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.
>
> I think the issue found here is independent of the other. This patch
> shouldn't need to wait for the other to land.
>

Yes, this one is - and can land - independently.
Without Jian's fix and CONFIG_HYPERV=m we have not seen the issue.

> >
> > Cc: Jian Cai <caij2003@...il.com>
> > Cc: clang-built-linux@...glegroups.com
> > Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
> > Fixes: a16be368dd3f ("x86/entry: Convert various hypervisor vectors to IDTENTRY_SYSVEC")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1043
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1088
> > Signed-off-by: Sedat Dilek <sedat.dilek@...il.com>
> > ---
> >  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 513eb2ccbdbf..a811f6c6cf15 100644
> > --- a/arch/x86/include/asm/idtentry.h
> > +++ b/arch/x86/include/asm/idtentry.h
> > @@ -624,8 +624,8 @@ 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);
>
> Reviewed-by: Wei Liu <wei.liu@...nel.org>
>

Thanks for your review.

- Sedat -

> Thomas, can you pick this up for 5.8? Thanks.
>
> Wei.