The 64-bit argument for the "get DIMM info" SMC call consists of
"mem_ctrl_idx" left-shifted 16 bits and OR-ed with DIMM index.
With "mem_ctrl_idx" defined as 32-bits wide the left-shift operation
truncates the upper 16 bits of information during the calculation
of the SMC argument. The "mem_ctrl_idx" stack variable must be
defined as 64-bits wide to prevent any potential integer overflow,
i.e. loss of data from upper 16 bits.

Fixes: 82413e562ea6 ("EDAC, mellanox: Add ECC support for BlueField DDR4")
Reviewed-by: Shravan Kumar Ramani <shravankr@nvidia.com>
Signed-off-by: David Thompson <davthompson@nvidia.com>
---
 drivers/edac/bluefield_edac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/edac/bluefield_edac.c b/drivers/edac/bluefield_edac.c
index 5b3164560648..0e539c107351 100644
--- a/drivers/edac/bluefield_edac.c
+++ b/drivers/edac/bluefield_edac.c
@@ -180,7 +180,7 @@ static void bluefield_edac_check(struct mem_ctl_info *mci)
 static void bluefield_edac_init_dimms(struct mem_ctl_info *mci)
 {
 	struct bluefield_edac_priv *priv = mci->pvt_info;
-	int mem_ctrl_idx = mci->mc_idx;
+	u64 mem_ctrl_idx = mci->mc_idx;
 	struct dimm_info *dimm;
 	u64 smc_info, smc_arg;
 	int is_empty = 1, i;
-- 
2.30.1

On Mon, Sep 30, 2024 at 11:10:56AM -0400, David Thompson wrote:
> The 64-bit argument for the "get DIMM info" SMC call consists of
> "mem_ctrl_idx" left-shifted 16 bits and OR-ed with DIMM index.
> With "mem_ctrl_idx" defined as 32-bits wide the left-shift operation
> truncates the upper 16 bits of information during the calculation
> of the SMC argument. The "mem_ctrl_idx" stack variable must be
> defined as 64-bits wide to prevent any potential integer overflow,
> i.e. loss of data from upper 16 bits.
> 
> Fixes: 82413e562ea6 ("EDAC, mellanox: Add ECC support for BlueField DDR4")
> Reviewed-by: Shravan Kumar Ramani <shravankr@nvidia.com>
> Signed-off-by: David Thompson <davthompson@nvidia.com>
> ---
>  drivers/edac/bluefield_edac.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/edac/bluefield_edac.c b/drivers/edac/bluefield_edac.c
> index 5b3164560648..0e539c107351 100644
> --- a/drivers/edac/bluefield_edac.c
> +++ b/drivers/edac/bluefield_edac.c
> @@ -180,7 +180,7 @@ static void bluefield_edac_check(struct mem_ctl_info *mci)
>  static void bluefield_edac_init_dimms(struct mem_ctl_info *mci)
>  {
>  	struct bluefield_edac_priv *priv = mci->pvt_info;
> -	int mem_ctrl_idx = mci->mc_idx;
> +	u64 mem_ctrl_idx = mci->mc_idx;
>  	struct dimm_info *dimm;
>  	u64 smc_info, smc_arg;
>  	int is_empty = 1, i;
> -- 

Is this something you're hitting in real workloads so that it needs to go to
stable or is it rather something caught through code review or so?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette