[PATCH] arm64: hibernate: reduce TLB maintenance scope

[PATCH] arm64: hibernate: reduce TLB maintenance scope

[Mark Rutland]

In break_before_make_ttbr_switch we perform broadcast TLB maintenance
for the inner shareable domain, and use a DSB ISH to complete this.
However, at the point we execute this, secondary CPUs are either
physically offline, or executing code outside of the kernel. Upon
entering the kernel, secondary CPUs will invalidate their TLBs before
enabling their MMUs.

Thus we do not need to invalidate TLBs of other CPUs, and as with
idmap_cpu_replace_ttbr1 we can reduce the scope of maintenance to the
TLBs of the local CPU. This keeps our TLB maintenance code consistent,
and is a minor optimisation.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/kernel/hibernate-asm.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S
index 46f29b6..7734f3e 100644
--- a/arch/arm64/kernel/hibernate-asm.S
+++ b/arch/arm64/kernel/hibernate-asm.S
@@ -36,8 +36,8 @@
 .macro break_before_make_ttbr_switch zero_page, page_table
 	msr	ttbr1_el1, \zero_page
 	isb
-	tlbi	vmalle1is
-	dsb	ish
+	tlbi	vmalle1
+	dsb	nsh
 	msr	ttbr1_el1, \page_table
 	isb
 .endm
-- 
1.9.1

[PATCH] arm64: hibernate: reduce TLB maintenance scope

[James Morse]

On 08/08/16 11:12, Mark Rutland wrote:
> In break_before_make_ttbr_switch we perform broadcast TLB maintenance
> for the inner shareable domain, and use a DSB ISH to complete this.
> However, at the point we execute this, secondary CPUs are either
> physically offline, or executing code outside of the kernel. Upon
> entering the kernel, secondary CPUs will invalidate their TLBs before
> enabling their MMUs.
> 
> Thus we do not need to invalidate TLBs of other CPUs, and as with
> idmap_cpu_replace_ttbr1 we can reduce the scope of maintenance to the
> TLBs of the local CPU. This keeps our TLB maintenance code consistent,
> and is a minor optimisation.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm64/kernel/hibernate-asm.S | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S
> index 46f29b6..7734f3e 100644
> --- a/arch/arm64/kernel/hibernate-asm.S
> +++ b/arch/arm64/kernel/hibernate-asm.S
> @@ -36,8 +36,8 @@
>  .macro break_before_make_ttbr_switch zero_page, page_table
>  	msr	ttbr1_el1, \zero_page
>  	isb
> -	tlbi	vmalle1is
> -	dsb	ish
> +	tlbi	vmalle1
> +	dsb	nsh
>  	msr	ttbr1_el1, \page_table
>  	isb
>  .endm
> 


Looks like what I should have done from the beginning!

Acked-by: James Morse <james.morse@arm.com>


Thanks,


James