Re: [PATCH v2] hw/arm/smmuv3: add support for stage 1 access fault

[Mostafa Saleh <smostafa@google.com>]

Hi Luc,

On Tue, Feb 13, 2024 at 09:22:11AM +0100, Luc Michel wrote:
> An access fault is raised when the Access Flag is not set in the
> looked-up PTE and the AFFD field is not set in the corresponding context
> descriptor. This was already implemented for stage 2. Implement it for
> stage 1 as well.
> 

I noticed the same thing when writing PTW for stage-2, I don’t think there is
any reason this is not supported for stage-1, as SMMUv3.0-HTTU* are not
supported any SW broken will be due to an existing SW bug.

Reviewed-by: Mostafa Saleh <smostafa@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>


> Signed-off-by: Luc Michel <luc.michel@amd.com>
> ---
> 
> v2: drop erroneous submodule modification
> 
> ---
> 
>  hw/arm/smmuv3-internal.h     |  1 +
>  include/hw/arm/smmu-common.h |  1 +
>  hw/arm/smmu-common.c         | 10 ++++++++++
>  hw/arm/smmuv3.c              |  1 +
>  4 files changed, 13 insertions(+)
> 
> diff --git a/hw/arm/smmuv3-internal.h b/hw/arm/smmuv3-internal.h
> index e987bc4686b..e4dd11e1e62 100644
> --- a/hw/arm/smmuv3-internal.h
> +++ b/hw/arm/smmuv3-internal.h
> @@ -622,10 +622,11 @@ static inline int pa_range(STE *ste)
>  #define CD_TSZ(x, sel)   extract32((x)->word[0], (16 * (sel)) + 0, 6)
>  #define CD_TG(x, sel)    extract32((x)->word[0], (16 * (sel)) + 6, 2)
>  #define CD_EPD(x, sel)   extract32((x)->word[0], (16 * (sel)) + 14, 1)
>  #define CD_ENDI(x)       extract32((x)->word[0], 15, 1)
>  #define CD_IPS(x)        extract32((x)->word[1], 0 , 3)
> +#define CD_AFFD(x)       extract32((x)->word[1], 3 , 1)
>  #define CD_TBI(x)        extract32((x)->word[1], 6 , 2)
>  #define CD_HD(x)         extract32((x)->word[1], 10 , 1)
>  #define CD_HA(x)         extract32((x)->word[1], 11 , 1)
>  #define CD_S(x)          extract32((x)->word[1], 12, 1)
>  #define CD_R(x)          extract32((x)->word[1], 13, 1)
> diff --git a/include/hw/arm/smmu-common.h b/include/hw/arm/smmu-common.h
> index fd8d772da11..5ec2e6c1a43 100644
> --- a/include/hw/arm/smmu-common.h
> +++ b/include/hw/arm/smmu-common.h
> @@ -90,10 +90,11 @@ typedef struct SMMUTransCfg {
>      /* Shared fields between stage-1 and stage-2. */
>      int stage;                 /* translation stage */
>      bool disabled;             /* smmu is disabled */
>      bool bypassed;             /* translation is bypassed */
>      bool aborted;              /* translation is aborted */
> +    bool affd;                 /* AF fault disable */
>      uint32_t iotlb_hits;       /* counts IOTLB hits */
>      uint32_t iotlb_misses;     /* counts IOTLB misses*/
>      /* Used by stage-1 only. */
>      bool aa64;                 /* arch64 or aarch32 translation table */
>      bool record_faults;        /* record fault events */
> diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
> index 9a8ac45431a..09ff72e55f5 100644
> --- a/hw/arm/smmu-common.c
> +++ b/hw/arm/smmu-common.c
> @@ -362,10 +362,20 @@ static int smmu_ptw_64_s1(SMMUTransCfg *cfg,
>                                          &block_size);
>              trace_smmu_ptw_block_pte(stage, level, baseaddr,
>                                       pte_addr, pte, iova, gpa,
>                                       block_size >> 20);
>          }
> +
> +        /*
> +         * If AFFD and PTE.AF are 0 => fault. (5.4. Context Descriptor)
> +         * An Access fault takes priority over a Permission fault.
> +         */
> +        if (!PTE_AF(pte) && !cfg->affd) {
> +            info->type = SMMU_PTW_ERR_ACCESS;
> +            goto error;
> +        }
> +
>          ap = PTE_AP(pte);
>          if (is_permission_fault(ap, perm)) {
>              info->type = SMMU_PTW_ERR_PERMISSION;
>              goto error;
>          }
> diff --git a/hw/arm/smmuv3.c b/hw/arm/smmuv3.c
> index 68eeef3e1d4..c416b8c0030 100644
> --- a/hw/arm/smmuv3.c
> +++ b/hw/arm/smmuv3.c
> @@ -682,10 +682,11 @@ static int decode_cd(SMMUTransCfg *cfg, CD *cd, SMMUEventInfo *event)
>  
>      cfg->oas = oas2bits(CD_IPS(cd));
>      cfg->oas = MIN(oas2bits(SMMU_IDR5_OAS), cfg->oas);
>      cfg->tbi = CD_TBI(cd);
>      cfg->asid = CD_ASID(cd);
> +    cfg->affd = CD_AFFD(cd);
>  
>      trace_smmuv3_decode_cd(cfg->oas);
>  
>      /* decode data dependent on TT */
>      for (i = 0; i <= 1; i++) {
> -- 
> 2.39.2

Thanks,
Mostafa