Re: [PATCH v6 02/15] drivers/smmu-v3: Fix impending MISRA R20.6 violation

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

+ Rahul

On Wed, 16 Apr 2025, Andrew Cooper wrote:
> cpu_to_le64() is about to become a macro, at which point the #ifdef in the
> middle of it becomes undefined behaviour.
> 
> Use a logcal variable to prepare strtab, where the #ifdef is fine to use.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> CC: Michal Orzel <michal.orzel@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> CC: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
> CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> CC: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> CC: Lin Liu <lin.liu@xxxxxxxxxx>
> 
> v6:
>  * New
> 
> Eclair log from v5:
>   
> https://saas.eclairit.com:3787/fs/var/local/eclair/xen-project.ecdf/xen-project/people/andyhhp/xen/ECLAIR_normal/xen-bswap/ARM64/9556392204/PROJECT.ecd;/by_service/MC3A2.R20.6.html
> ---
>  xen/drivers/passthrough/arm/smmu-v3.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
> b/xen/drivers/passthrough/arm/smmu-v3.c
> index cee572402203..df162350578c 100644
> --- a/xen/drivers/passthrough/arm/smmu-v3.c
> +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> @@ -722,15 +722,17 @@ static void arm_smmu_write_strtab_ent(struct 
> arm_smmu_master *master, u32 sid,
>       }
>  
>       if (s2_cfg) {
> -             BUG_ON(ste_live);
> -             dst[2] = cpu_to_le64(
> +             u64 strtab =
>                        FIELD_PREP(STRTAB_STE_2_S2VMID, s2_cfg->vmid) |
>                        FIELD_PREP(STRTAB_STE_2_VTCR, s2_cfg->vtcr) |
>  #ifdef __BIG_ENDIAN
>                        STRTAB_STE_2_S2ENDI |
>  #endif
>                        STRTAB_STE_2_S2PTW | STRTAB_STE_2_S2AA64 |
> -                      STRTAB_STE_2_S2R);
> +                      STRTAB_STE_2_S2R;
> +
> +             BUG_ON(ste_live);
> +             dst[2] = cpu_to_le64(strtab);
>  
>               dst[3] = cpu_to_le64(s2_cfg->vttbr & STRTAB_STE_3_S2TTB_MASK);
>  
> -- 
> 2.39.5
>