linux-kernel - Re: [PATCHv2 1/3] x86/tdx: Fix early #VE handling

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Message-ID: <72c0c7ff-35db-eb8e-0220-87baed2a3cd8@linux.intel.com>
Date:   Fri, 20 May 2022 10:46:09 -0700
From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...el.com, luto@...nel.org, peterz@...radead.org
Cc:     ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, linux-kernel@...r.kernel.org, seanjc@...gle.com,
        thomas.lendacky@....com, x86@...nel.org
Subject: Re: [PATCHv2 1/3] x86/tdx: Fix early #VE handling



On 5/19/22 8:13 PM, Kirill A. Shutemov wrote:
> Move RIP in tdx_early_handle_ve() after handling the exception. Failure
> to do that leads to infinite loop of exceptions.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Fixes: 32e72854fa5f ("x86/tdx: Port I/O: Add early boot support")
> ---
>   arch/x86/coco/tdx/tdx.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)

Looks good to me

Reviewed-by: Kuppuswamy Sathyanarayanan 
<sathyanarayanan.kuppuswamy@...ux.intel.com>

> 
> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> index 03deb4d6920d..faae53f8d559 100644
> --- a/arch/x86/coco/tdx/tdx.c
> +++ b/arch/x86/coco/tdx/tdx.c
> @@ -447,13 +447,17 @@ static bool handle_io(struct pt_regs *regs, u32 exit_qual)
>   __init bool tdx_early_handle_ve(struct pt_regs *regs)
>   {
>   	struct ve_info ve;
> +	bool ret;
>   
>   	tdx_get_ve_info(&ve);
>   
>   	if (ve.exit_reason != EXIT_REASON_IO_INSTRUCTION)
>   		return false;
>   
> -	return handle_io(regs, ve.exit_qual);
> +	ret = handle_io(regs, ve.exit_qual);
> +	if (ret)
> +		regs->ip += ve.instr_len;
> +	return ret;
>   }
>   
>   void tdx_get_ve_info(struct ve_info *ve)

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer