Re: [PATCH] xen/arm: Document the erratum #853709 related to Cortex A72

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi,

> On 14 Oct 2020, at 11:05, Michal Orzel <Michal.Orzel@xxxxxxx> wrote:
> 
> Workaround for Cortex-A57 erratum #852523 is already
> in Xen but Cortex-A72 erratum #853709 is not although
> it applies to the same issue.
> 
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

Change in commit message suggested by Julien is quite right and
should be added.

Bertrand

> ---
> docs/misc/arm/silicon-errata.txt | 1 +
> xen/arch/arm/domain.c            | 6 ++++--
> 2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/docs/misc/arm/silicon-errata.txt 
> b/docs/misc/arm/silicon-errata.txt
> index e15d0923e9..1f18a9df58 100644
> --- a/docs/misc/arm/silicon-errata.txt
> +++ b/docs/misc/arm/silicon-errata.txt
> @@ -50,6 +50,7 @@ stable hypervisors.
> | ARM            | Cortex-A57      | #834220         | ARM64_ERRATUM_834220   
>  |
> | ARM            | Cortex-A57      | #1319537        | N/A                    
>  |
> | ARM            | Cortex-A72      | #1319367        | N/A                    
>  |
> +| ARM            | Cortex-A72      | #853709         | N/A                   
>   |
> | ARM            | Cortex-A76      | #1165522        | N/A                    
>  |
> | ARM            | Neoverse-N1     | #1165522        | N/A
> | ARM            | MMU-500         | #842869         | N/A                    
>  |
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 3b37f899b9..18cafcdda7 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -216,7 +216,8 @@ static void ctxt_switch_to(struct vcpu *n)
>     WRITE_SYSREG64(n->arch.ttbr1, TTBR1_EL1);
> 
>     /*
> -     * Erratum #852523: DACR32_EL2 must be restored before one of the
> +     * Erratum #852523 (Cortex-A57) or erratum #853709 (Cortex-A72):
> +     * DACR32_EL2 must be restored before one of the
>      * following sysregs: SCTLR_EL1, TCR_EL1, TTBR0_EL1, TTBR1_EL1 or
>      * CONTEXTIDR_EL1.
>      */
> @@ -245,7 +246,8 @@ static void ctxt_switch_to(struct vcpu *n)
> 
>     /*
>      * This write to sysreg CONTEXTIDR_EL1 ensures we don't hit erratum
> -     * #852523. I.e DACR32_EL2 is not correctly synchronized.
> +     * #852523 (Cortex-A57) or #853709 (Cortex-A72).
> +     * I.e DACR32_EL2 is not correctly synchronized.
>      */
>     WRITE_SYSREG(n->arch.contextidr, CONTEXTIDR_EL1);
>     WRITE_SYSREG(n->arch.tpidr_el0, TPIDR_EL0);
> -- 
> 2.28.0
>