Re: [PATCH v4 03/11] xen/arm: smmuv3: Revert patch related to XArray

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 8 Jan 2021, Rahul Singh wrote:
> XArray is not implemented in XEN revert the patch that introduce the
> XArray code in SMMUv3 driver.
> 
> XArray is added in preparation for sharing some ASIDs with the CPU,
> 
> As XEN support only Stage-2 translation, ASID is used for Stage-1
> translation there is no consequences of reverting this patch for XEN.
> 
> Once XArray is implemented in XEN this patch can be added in XEN if XEN
> supports Stage-1 translation.
> 
> Reverted the commit 0299a1a81ca056e79c1a7fb751f936ec0d5c7afe
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes in V3:
> - Added consequences of reverting this patch in commit message
> Changes in V4: Rebase
> ---
>  xen/drivers/passthrough/arm/smmu-v3.c | 27 +++++++++------------------
>  1 file changed, 9 insertions(+), 18 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
> b/xen/drivers/passthrough/arm/smmu-v3.c
> index 8b7747ed38..7b29ead48c 100644
> --- a/xen/drivers/passthrough/arm/smmu-v3.c
> +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> @@ -625,6 +625,7 @@ struct arm_smmu_device {
>  
>  #define ARM_SMMU_MAX_ASIDS           (1 << 16)
>       unsigned int                    asid_bits;
> +     DECLARE_BITMAP(asid_map, ARM_SMMU_MAX_ASIDS);
>  
>  #define ARM_SMMU_MAX_VMIDS           (1 << 16)
>       unsigned int                    vmid_bits;
> @@ -690,8 +691,6 @@ struct arm_smmu_option_prop {
>       const char *prop;
>  };
>  
> -static DEFINE_XARRAY_ALLOC1(asid_xa);
> -
>  static struct arm_smmu_option_prop arm_smmu_options[] = {
>       { ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
>       { ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
> @@ -1346,14 +1345,6 @@ static void arm_smmu_free_cd_tables(struct 
> arm_smmu_domain *smmu_domain)
>       cdcfg->cdtab = NULL;
>  }
>  
> -static void arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd)
> -{
> -     if (!cd->asid)
> -             return;
> -
> -     xa_erase(&asid_xa, cd->asid);
> -}
> -
>  /* Stream table manipulation functions */
>  static void
>  arm_smmu_write_strtab_l1_desc(__le64 *dst, struct arm_smmu_strtab_l1_desc 
> *desc)
> @@ -1988,9 +1979,10 @@ static void arm_smmu_domain_free(struct iommu_domain 
> *domain)
>       if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
>               struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
>  
> -             if (cfg->cdcfg.cdtab)
> +             if (cfg->cdcfg.cdtab) {
>                       arm_smmu_free_cd_tables(smmu_domain);
> -             arm_smmu_free_asid(&cfg->cd);
> +                     arm_smmu_bitmap_free(smmu->asid_map, cfg->cd.asid);
> +             }
>       } else {
>               struct arm_smmu_s2_cfg *cfg = &smmu_domain->s2_cfg;
>               if (cfg->vmid)
> @@ -2005,15 +1997,14 @@ static int arm_smmu_domain_finalise_s1(struct 
> arm_smmu_domain *smmu_domain,
>                                      struct io_pgtable_cfg *pgtbl_cfg)
>  {
>       int ret;
> -     u32 asid;
> +     int asid;
>       struct arm_smmu_device *smmu = smmu_domain->smmu;
>       struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
>       typeof(&pgtbl_cfg->arm_lpae_s1_cfg.tcr) tcr = 
> &pgtbl_cfg->arm_lpae_s1_cfg.tcr;
>  
> -     ret = xa_alloc(&asid_xa, &asid, &cfg->cd,
> -                    XA_LIMIT(1, (1 << smmu->asid_bits) - 1), GFP_KERNEL);
> -     if (ret)
> -             return ret;
> +     asid = arm_smmu_bitmap_alloc(smmu->asid_map, smmu->asid_bits);
> +     if (asid < 0)
> +             return asid;
>  
>       cfg->s1cdmax = master->ssid_bits;
>  
> @@ -2046,7 +2037,7 @@ static int arm_smmu_domain_finalise_s1(struct 
> arm_smmu_domain *smmu_domain,
>  out_free_cd_tables:
>       arm_smmu_free_cd_tables(smmu_domain);
>  out_free_asid:
> -     arm_smmu_free_asid(&cfg->cd);
> +     arm_smmu_bitmap_free(smmu->asid_map, asid);
>       return ret;
>  }
>  
> -- 
> 2.17.1
>