[v2,7/7] mm: secretmem: add ability to reserve memory at boot
diff mbox series

Message ID 20200727162935.31714-8-rppt@kernel.org
State New
Headers show
Series
  • mm: introduce memfd_secret system call to create "secret" memory areas
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Commit Message

Mike Rapoport July 27, 2020, 4:29 p.m. UTC
From: Mike Rapoport <rppt@linux.ibm.com>

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 <rppt@linux.ibm.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Mike Rapoport July 27, 2020, 5:11 p.m. UTC | #1
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 <rppt@linux.ibm.com>
> 
> 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 <rppt@linux.ibm.com>
> ---
>  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
>

Patch
diff mbox series

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.