Re: [RFC v4 09/31] hw/arm/smmuv3: Enforce Secure stage 2 capability check when decoding STE

[Mostafa Saleh <smostafa@google.com>]

On Sat, Feb 21, 2026 at 06:02:28PM +0800, Tao Tang wrote:
> When decoding a Stream Table Entry (STE) from the Secure stream table
> that enables stage-2 translation, verify that the SMMU implementation
> advertises Secure stage-2 support via S_IDR1.SEL2. If stage-2 is
> requested but S_IDR1.SEL2 is 0, mark the STE as ILLEGAL.
> 
> This implements the requirement from the Arm SMMUv3 architecture
> specification (IHI 0070G.b, Section 5.2, Page 218) that a Secure STE
> with stage-2 enabled is only valid when the implementation supports
> Secure stage-2 translation.
> 
> Signed-off-by: Tao Tang <tangtao1634@phytium.com.cn>
> ---
>  hw/arm/smmuv3.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 2192bec2368..d011357253e 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -623,6 +623,16 @@ static int decode_ste(SMMUv3State *s, SMMUTransCfg *cfg,
>          if (ret) {
>              goto bad_ste;
>          }
> +
> +        /*
> +         * Stage 2 is implemented but Secure stage 2 is not supported while
> +         * STE is from Secure stream table. STE is ILLEGAL in this case
> +         * according to (IHI 0070G.b) 5.2 STE, Stream Table Entry, Page 218.
> +         */
> +        if ((cfg->sec_sid == SMMU_SEC_SID_S) &&
> +            !(FIELD_EX32(s->bank[SMMU_SEC_SID_S].idr[1], S_IDR1, SEL2))) {
> +            goto bad_ste;
> +        }
The IDR is not currently set, we can just safely return bad_ste for
“SMMU_SEC_SID_S”, no need to complicate things until SEL2 is supported.

Thanks,
Mostafa

>      }
>  
>      /* Multiple context descriptors require SubstreamID support */
> -- 
> 2.34.1
>