[edk2-devel] [PATCH] ArmVirtPkg/ArmVirtMemoryInitPeiLib: avoid redundant cache invalidation
Alexander Graf via groups.io
graf=amazon.com at groups.io
Mon Jan 31 13:21:13 UTC 2022
On 29.01.22 16:13, Ard Biesheuvel wrote:
> Alex reports that the cache invalidation performed by
> ArmVirtMemoryInitPeiLib takes a non-negligible amount of time at boot.
> This cache invalidation used to be necessary to avoid inconsistencies
> between the CPU's cached and uncached views of the permanent PEI memory
> region, given that the PEI phase is where the MMU gets enabled.
>
> The only allocations done from permanent PEI memory with the MMU off are
> pages used for page tables, and since commit 748fea6279ef
> ("ArmPkg/ArmMmuLib AARCH64: invalidate page tables before populating
> them"), each of those is invalidated in the caches explicitly, for
> reasons described in the patch's commit log. All other allocations done
> in PEI are either from temporary PEI memory, which includes the stack,
> or from permanent PEI memory but after the MMU has been enabled.
>
> This means that the cache invalidation in ArmVirtMemoryInitPeiLib is no
> longer necessary, and can simply be dropped.
>
> Cc: Alexander Graf <agraf at csgraf.de>
> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
Reviewed-by: Alexander Graf <graf at amazon.com>
Also, feel free to add
Reported-by: Alexander Graf <graf at amazon.com>
Thanks a bunch!
Alex
> ---
> .../ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c | 9 ---------
> 1 file changed, 9 deletions(-)
>
> diff --git a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> index 022e13e762b6..98d90ad4200d 100644
> --- a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> +++ b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> @@ -91,15 +91,6 @@ MemoryPeim (
> );
> }
>
> - //
> - // When running under virtualization, the PI/UEFI memory region may be
> - // clean but not invalidated in system caches or in lower level caches
> - // on other CPUs. So invalidate the region by virtual address, to ensure
> - // that the contents we put there with the caches and MMU off will still
> - // be visible after turning them on.
> - //
> - InvalidateDataCacheRange ((VOID *)(UINTN)UefiMemoryBase, UefiMemorySize);
> -
> // Build Memory Allocation Hob
> InitMmu ();
>
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#86251): https://edk2.groups.io/g/devel/message/86251
Mute This Topic: https://groups.io/mt/88767635/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-
More information about the edk2-devel-archive
mailing list