linux-kernel - Re: [PATCH v11 05/12] x86/mm: add INVLPGB support code

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Message-ID: <20250219120441.GNZ7XI2aWWUmXh2H2m@fat_crate.local>
Date: Wed, 19 Feb 2025 13:04:41 +0100
From: Borislav Petkov <bp@...en8.de>
To: Rik van Riel <riel@...riel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, peterz@...radead.org,
	dave.hansen@...ux.intel.com, zhengqi.arch@...edance.com,
	nadav.amit@...il.com, thomas.lendacky@....com, kernel-team@...a.com,
	linux-mm@...ck.org, akpm@...ux-foundation.org, jackmanb@...gle.com,
	jannh@...gle.com, mhklinux@...look.com, andrew.cooper3@...rix.com,
	Manali Shukla <Manali.Shukla@....com>
Subject: Re: [PATCH v11 05/12] x86/mm: add INVLPGB support code

On Thu, Feb 13, 2025 at 11:13:56AM -0500, Rik van Riel wrote:
> Add invlpgb.h with the helper functions and definitions needed to use
> broadcast TLB invalidation on AMD EPYC 3 and newer CPUs.
> 
> Signed-off-by: Rik van Riel <riel@...riel.com>
> Tested-by: Manali Shukla <Manali.Shukla@....com>
> Tested-by: Brendan Jackman <jackmanb@...gle.com>
> Tested-by: Michael Kelley <mhklinux@...look.com>
> ---
>  arch/x86/include/asm/disabled-features.h |   8 +-
>  arch/x86/include/asm/invlpgb.h           | 101 +++++++++++++++++++++++
>  arch/x86/include/asm/tlbflush.h          |   1 +
>  3 files changed, 109 insertions(+), 1 deletion(-)
>  create mode 100644 arch/x86/include/asm/invlpgb.h
> 
> diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
> index c492bdc97b05..625a89259968 100644
> --- a/arch/x86/include/asm/disabled-features.h
> +++ b/arch/x86/include/asm/disabled-features.h
> @@ -129,6 +129,12 @@
>  #define DISABLE_SEV_SNP		(1 << (X86_FEATURE_SEV_SNP & 31))
>  #endif
>  
> +#ifdef CONFIG_X86_BROADCAST_TLB_FLUSH
> +#define DISABLE_INVLPGB		0
> +#else
> +#define DISABLE_INVLPGB		(1 << (X86_FEATURE_INVLPGB & 31))
> +#endif
> +

What does that bring you really in savings?

>  /*
>   * Make sure to add features to the correct mask
>   */
> @@ -146,7 +152,7 @@
>  #define DISABLED_MASK11	(DISABLE_RETPOLINE|DISABLE_RETHUNK|DISABLE_UNRET| \
>  			 DISABLE_CALL_DEPTH_TRACKING|DISABLE_USER_SHSTK)
>  #define DISABLED_MASK12	(DISABLE_FRED|DISABLE_LAM)
> -#define DISABLED_MASK13	0
> +#define DISABLED_MASK13	(DISABLE_INVLPGB)
>  #define DISABLED_MASK14	0
>  #define DISABLED_MASK15	0
>  #define DISABLED_MASK16	(DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP| \
> diff --git a/arch/x86/include/asm/invlpgb.h b/arch/x86/include/asm/invlpgb.h
> new file mode 100644
> index 000000000000..a1d5dedd5217
> --- /dev/null
> +++ b/arch/x86/include/asm/invlpgb.h

I remember asking you to add all that gunk to arch/x86/include/asm/tlb.h.
Please do so.

> +#define INVLPGB_VA			BIT(0)
> +#define INVLPGB_PCID			BIT(1)
> +#define INVLPGB_ASID			BIT(2)
> +#define INVLPGB_INCLUDE_GLOBAL		BIT(3)
> +#define INVLPGB_FINAL_ONLY		BIT(4)
> +#define INVLPGB_INCLUDE_NESTED		BIT(5)
> +
> +/* Flush all mappings for a given pcid and addr, not including globals. */
> +static inline void invlpgb_flush_user(unsigned long pcid,
> +				      unsigned long addr)

Please drop this unused function.

-- 
Regards/Gruss,
    Boris.

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