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

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Date:   Mon, 13 Jul 2020 11:13:30 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Sedat Dilek <sedat.dilek@...il.com>
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>,
        Wei Liu <wei.liu@...nel.org>, linux-kernel@...r.kernel.org,
        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 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.

> 
> 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>

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

Wei.