linux-kernel - Re: [PATCH v3 02/12] x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid

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Message-ID: <20230727125228.rtayk33s3diflqkm@box.shutemov.name>
Date:   Thu, 27 Jul 2023 15:52:28 +0300
From:   kirill.shutemov@...ux.intel.com
To:     Kai Huang <kai.huang@...el.com>
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, tglx@...utronix.de, bp@...en8.de,
        mingo@...hat.com, hpa@...or.com, x86@...nel.org, seanjc@...gle.com,
        pbonzini@...hat.com, isaku.yamahata@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com,
        n.borisov.lkml@...il.com
Subject: Re: [PATCH v3 02/12] x86/tdx: Skip saving output regs when SEAMCALL
 fails with VMFailInvalid

On Wed, Jul 26, 2023 at 11:25:04PM +1200, Kai Huang wrote:
> If SEAMCALL fails with VMFailInvalid, the SEAM software (e.g., the TDX
> module) won't have chance to set any output register.  Skip saving the
> output registers to the structure in this case.
> 
> Also, as '.Lno_output_struct' is the very last symbol before RET, rename
> it to '.Lout' to make it short.
> 
> Opportunistically make the asm directives unindented.
> 
> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> ---
> 
> v2 -> v3:
>  - No change.
> 
> v1 -> v2:
>  - A new patch to improve SEAMCALL VMFailInvalid failure, with v1 patch
>    "x86/tdx: Move FRAME_BEGIN/END to TDX_MODULE_CALL asm macro" merged.
> 
> ---
>  arch/x86/coco/tdx/tdcall.S      |  3 ---
>  arch/x86/virt/vmx/tdx/tdxcall.S | 29 ++++++++++++++++++++---------
>  2 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
> index 2eca5f43734f..e5d4b7d8ecd4 100644
> --- a/arch/x86/coco/tdx/tdcall.S
> +++ b/arch/x86/coco/tdx/tdcall.S
> @@ -78,10 +78,7 @@
>   * Return status of TDCALL via RAX.
>   */
>  SYM_FUNC_START(__tdx_module_call)
> -	FRAME_BEGIN
>  	TDX_MODULE_CALL host=0
> -	FRAME_END
> -	RET
>  SYM_FUNC_END(__tdx_module_call)
>  

Do we still need to include asm/frame.h after the change?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov