Subject: Re: [PATCH v2 7/7] mm: secretmem: add ability to reserve memory at boot

From: Mike Rapoport <[email-masked]>
Date: Mon, 27 Jul 2020 20:11:02 +0300

Oops, something went wrong with the rebase, this should have been
squashed into the previous patch...

On Mon, Jul 27, 2020 at 07:29:35PM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <[email-masked]>
> 
> Taking pages out from the direct map and bringing them back may create
> undesired fragmentation and usage of the smaller pages in the direct
> mapping of the physical memory.
> 
> This can be avoided if a significantly large area of the physical memory
> would be reserved for secretmem purposes at boot time.
> 
> Add ability to reserve physical memory for secretmem at boot time using
> "secretmem" kernel parameter and then use that reserved memory as a global
> pool for secret memory needs.
> 
> Signed-off-by: Mike Rapoport <[email-masked]>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index fb95fad81c79..6f3c2f28160f 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4548,6 +4548,10 @@
>  			Format: integer between 0 and 10
>  			Default is 0.
>  
> +	secretmem=n[KMG]
> +			[KNL,BOOT] Reserve specified amount of memory to
> +			back mappings of secret memory.
> +
>  	skew_tick=	[KNL] Offset the periodic timer tick per cpu to mitigate
>  			xtime_lock contention on larger systems, and/or RCU lock
>  			contention on all systems with CONFIG_MAXSMP set.
> -- 
> 2.26.2
> 

-- 
Sincerely yours,
Mike.

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