Re: [PATCH v4 11/19] hw/arm/smmu-common: Support nested translation

[Eric Auger]

Hi Mostafa,

On 7/1/24 13:02, Mostafa Saleh wrote:
> When nested translation is requested, do the following:
>
> - Translate stage-1 table address IPA into PA through stage-2.
> - Translate stage-1 table walk output (IPA) through stage-2.
> - Create a single TLB entry from stage-1 and stage-2 translations
>   using logic introduced before.
>
> For stage-1 table translation, the spec (ARM IHI 0070 F.b) says in:
>     7.3.12 F_WALK_EABT:
>         Translation of an IPA for Stage 1 descriptor fetch:
>       S2 == 1 (stage 2), CLASS == T
> So, F_WALK_EABT is used which propagtes to CLASS == TT.
>
> smmu_ptw() has a new argument SMMUState which include the TLB as
> stage-1 table address can be cached in there.
>
> Also in smmu_ptw() a separate path used for nesting to simplify the
> code, although some logic can be combined.
>
> Signed-off-by: Mostafa Saleh <smostafa@google.com>
> ---
>  hw/arm/smmu-common.c         | 72 +++++++++++++++++++++++++++++++-----
>  include/hw/arm/smmu-common.h |  2 +-
>  2 files changed, 64 insertions(+), 10 deletions(-)
>
> diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
> index 24b7d09e2b..71afd486ba 100644
> --- a/hw/arm/smmu-common.c
> +++ b/hw/arm/smmu-common.c
> @@ -318,6 +318,38 @@ SMMUTransTableInfo *select_tt(SMMUTransCfg *cfg, 
> dma_addr_t iova)
>      return NULL;
>  }
>  
> +/* Translate stage-1 table address using stage-2 page table. */
> +static inline int translate_table_addr_ipa(dma_addr_t *table_addr,
> +                                           SMMUTransCfg *cfg,
> +                                           SMMUPTWEventInfo *info,
> +                                           SMMUState *bs)
Nit: in general the SMMUState if the 1st arg, as the most global state.
> +{
> +    dma_addr_t addr = *table_addr;
> +    SMMUTLBEntry *cached_entry;
> +    int asid;
> +
> +    /*
> +     * The translation table walks performed from TTB0 or TTB1 are always
> +     * performed in IPA space if stage 2 translations are enabled.
> +     */
> +    asid = cfg->asid;
> +    cfg->stage = SMMU_STAGE_2;
> +    cfg->asid = -1;
> +    cached_entry = smmu_translate(bs, cfg, addr, IOMMU_RO, info);
> +    cfg->asid = asid;
> +    cfg->stage = SMMU_NESTED;
> +
> +    if (cached_entry) {
> +        *table_addr = CACHED_ENTRY_TO_ADDR(cached_entry, addr);
> +        return 0;
> +    }
> +
> +    info->stage = SMMU_STAGE_2;
> +    info->type = SMMU_PTW_ERR_WALK_EABT;
> +    info->addr = addr;
so I guess also here the recorded address should be the IOVA (Jean's
previous comment)?

Eric
> +    return -EINVAL;
> +}
> +
>  /**
>   * smmu_ptw_64_s1 - VMSAv8-64 Walk of the page tables for a given IOVA
>   * @cfg: translation config
> @@ -333,7 +365,8 @@ SMMUTransTableInfo *select_tt(SMMUTransCfg *cfg, 
> dma_addr_t iova)
>   */
>  static int smmu_ptw_64_s1(SMMUTransCfg *cfg,
>                            dma_addr_t iova, IOMMUAccessFlags perm,
> -                          SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info)
> +                          SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info,
> +                          SMMUState *bs)
>  {
>      dma_addr_t baseaddr, indexmask;
>      SMMUStage stage = cfg->stage;
> @@ -381,6 +414,11 @@ static int smmu_ptw_64_s1(SMMUTransCfg *cfg,
>                  goto error;
>              }
>              baseaddr = get_table_pte_address(pte, granule_sz);
> +            if (cfg->stage == SMMU_NESTED) {
> +                if (translate_table_addr_ipa(&baseaddr, cfg, info, bs)) {
> +                    goto error;
> +                }
> +            }
>              level++;
>              continue;
>          } else if (is_page_pte(pte, level)) {
> @@ -568,10 +606,8 @@ error:
>   * combine S1 and S2 TLB entries into a single entry.
>   * As a result the S1 entry is overriden with combined data.
>   */
> -static void __attribute__((unused)) combine_tlb(SMMUTLBEntry *tlbe,
> -                                                SMMUTLBEntry *tlbe_s2,
> -                                                dma_addr_t iova,
> -                                                SMMUTransCfg *cfg)
> +static void combine_tlb(SMMUTLBEntry *tlbe, SMMUTLBEntry *tlbe_s2,
> +                        dma_addr_t iova, SMMUTransCfg *cfg)
>  {
>      if (tlbe_s2->entry.addr_mask < tlbe->entry.addr_mask) {
>          tlbe->entry.addr_mask = tlbe_s2->entry.addr_mask;
> @@ -596,14 +632,19 @@ static void __attribute__((unused)) 
> combine_tlb(SMMUTLBEntry *tlbe,
>   * @perm: tentative access type
>   * @tlbe: returned entry
>   * @info: ptw event handle
> + * @bs: smmu state which includes TLB instance
>   *
>   * return 0 on success
>   */
>  int smmu_ptw(SMMUTransCfg *cfg, dma_addr_t iova, IOMMUAccessFlags perm,
> -             SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info)
> +             SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info, SMMUState *bs)
>  {
> +    int ret;
> +    SMMUTLBEntry tlbe_s2;
> +    dma_addr_t ipa;
> +
>      if (cfg->stage == SMMU_STAGE_1) {
> -        return smmu_ptw_64_s1(cfg, iova, perm, tlbe, info);
> +        return smmu_ptw_64_s1(cfg, iova, perm, tlbe, info, bs);
>      } else if (cfg->stage == SMMU_STAGE_2) {
>          /*
>           * If bypassing stage 1(or unimplemented), the input address is 
> passed
> @@ -621,7 +662,20 @@ int smmu_ptw(SMMUTransCfg *cfg, dma_addr_t iova, 
> IOMMUAccessFlags perm,
>          return smmu_ptw_64_s2(cfg, iova, perm, tlbe, info);
>      }
>  
> -    g_assert_not_reached();
> +    /* SMMU_NESTED. */
> +    ret = smmu_ptw_64_s1(cfg, iova, perm, tlbe, info, bs);
> +    if (ret) {
> +        return ret;
> +    }
> +
> +    ipa = CACHED_ENTRY_TO_ADDR(tlbe, iova);
> +    ret = smmu_ptw_64_s2(cfg, ipa, perm, &tlbe_s2, info);
> +    if (ret) {
> +        return ret;
> +    }
> +
> +    combine_tlb(tlbe, &tlbe_s2, iova, cfg);
> +    return 0;
>  }
>  
>  SMMUTLBEntry *smmu_translate(SMMUState *bs, SMMUTransCfg *cfg, dma_addr_t 
> addr,
> @@ -677,7 +731,7 @@ SMMUTLBEntry *smmu_translate(SMMUState *bs, SMMUTransCfg 
> *cfg, dma_addr_t addr,
>      }
>  
>      cached_entry = g_new0(SMMUTLBEntry, 1);
> -    status = smmu_ptw(cfg, aligned_addr, flag, cached_entry, info);
> +    status = smmu_ptw(cfg, aligned_addr, flag, cached_entry, info, bs);
>      if (status) {
>              g_free(cached_entry);
>              return NULL;
> diff --git a/include/hw/arm/smmu-common.h b/include/hw/arm/smmu-common.h
> index 1db566d451..cf0fd3ec74 100644
> --- a/include/hw/arm/smmu-common.h
> +++ b/include/hw/arm/smmu-common.h
> @@ -185,7 +185,7 @@ static inline uint16_t smmu_get_sid(SMMUDevice *sdev)
>   * pair, according to @cfg translation config
>   */
>  int smmu_ptw(SMMUTransCfg *cfg, dma_addr_t iova, IOMMUAccessFlags perm,
> -             SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info);
> +             SMMUTLBEntry *tlbe, SMMUPTWEventInfo *info, SMMUState *bs);
>  
>  
>  /*