Re: [PATCH v2] x86/sev: Fix operator precedence in GHCB_MSR_VMPL_REQ_LEVEL macro

[Borislav Petkov]

On Sun, May 11, 2025 at 06:23:28PM +0900, Seongmanlee wrote:
> From: leonardo-leecaprio <augustus92@xxxxxxxxxxx>
	^^^^^^^^^^^^^

Right, when you fix the name, you need to fix the authorship too:

$ git commit --amend --author="Seongman Lee <augustus92@xxxxxxxxxxx>"

as this name will appear in the git history.

But no worries, I'll fix it up when applying - just something to think about
in the future.

You can also set your name in .git/config or .gitconfig and then it'll be
correct automagically.

> The GHCB_MSR_VMPL_REQ_LEVEL macro lacked parentheses around the bitmask
> expression, causing the shift operation to bind too early. As a result,
> when switching to VMPL2 from VMPL1 (e.g., GHCB_MSR_VMPL_REQ_LEVEL(1)),
> incorrect values such as 0x000000016 were generated instead of the intended
> 0x100000016.
> 
> Fixes the precedence issue by grouping the masked value before applying
> the shift.
> 
> Fixes: 34ff65901735 ("x86/sev: Use kernel provided SVSM Calling Areas")
> 
> Signed-off-by: Seongman Lee <augustus92@xxxxxxxxxxx>
> ---
>  arch/x86/include/asm/sev-common.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index acb85b934..0020d77a0 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -116,7 +116,7 @@ enum psc_op {
>  #define GHCB_MSR_VMPL_REQ		0x016
>  #define GHCB_MSR_VMPL_REQ_LEVEL(v)			\
>  	/* GHCBData[39:32] */				\
> -	(((u64)(v) & GENMASK_ULL(7, 0) << 32) |		\
> +	((((u64)(v) & GENMASK_ULL(7, 0)) << 32) |	\
>  	/* GHCBDdata[11:0] */				\
>  	GHCB_MSR_VMPL_REQ)
>  
> -- 

Thx.

-- 
Regards/Gruss,
    Boris.

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