Re: [PATCH] arm64: Work around Falkor erratum 1009

[Mark Rutland]

On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:
> From: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
> 
> During a TLB invalidate sequence targeting the inner shareable
> domain, Falkor may prematurely complete the DSB before all loads
> and stores using the old translation are observed; instruction
> fetches are not subject to the conditions of this erratum.
> 
> Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
> Signed-off-by: Christopher Covington <cov@xxxxxxxxxxxxxx>
> ---
>  arch/arm64/Kconfig                | 10 +++++++++
>  arch/arm64/include/asm/cpucaps.h  |  3 ++-
>  arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/cpu_errata.c    |  7 +++++++
>  arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
>  5 files changed, 96 insertions(+), 6 deletions(-)

Please update Documentation/arm64/silicon-errata.txt respectively.

[...]

>  #include <linux/sched.h>
>  #include <asm/cputype.h>
> +#include <asm/alternative.h>

Nit: please keep includes (alphabetically) ordered (at least below the
linux/ or asm/ level).

[...]

> +	asm volatile(ALTERNATIVE(
> +		     "nop \n"
> +		     "nop \n",
> +		     "tlbi vmalle1is \n"
> +		     "dsb ish \n",

As a general note, perhaps we want a C compatible NOP_ALTERNATIVE() so
that the nop case can be implicitly generated for sequences like this.

Thanks,
Mark.