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Re: [PATCH v2 5/8] xen/arm: Remove support for PCI ATS on SMMUv3



On Thu, 26 Nov 2020, Rahul Singh wrote:
> PCI ATS functionality is not implemented and tested on ARM. Remove the
> PCI ATS support, once PCI ATS support is tested and available this
> patch can be added.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>

This looks like a revert of 9ce27afc0830f. Can we add that as a note to
the commit message?

One very minor comment at the bottom


> ---
>  xen/drivers/passthrough/arm/smmu-v3.c | 273 --------------------------
>  1 file changed, 273 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
> b/xen/drivers/passthrough/arm/smmu-v3.c
> index 401f7ae006..6a33628087 100644
> --- a/xen/drivers/passthrough/arm/smmu-v3.c
> +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> @@ -460,16 +460,6 @@ struct arm_smmu_cmdq_ent {
>                       u64                     addr;
>               } tlbi;
>  
> -             #define CMDQ_OP_ATC_INV         0x40
> -             #define ATC_INV_SIZE_ALL        52
> -             struct {
> -                     u32                     sid;
> -                     u32                     ssid;
> -                     u64                     addr;
> -                     u8                      size;
> -                     bool                    global;
> -             } atc;
> -
>               #define CMDQ_OP_PRI_RESP        0x41
>               struct {
>                       u32                     sid;
> @@ -632,7 +622,6 @@ struct arm_smmu_master {
>       struct list_head                domain_head;
>       u32                             *sids;
>       unsigned int                    num_sids;
> -     bool                            ats_enabled;
>       unsigned int                    ssid_bits;
>  };
>  
> @@ -650,7 +639,6 @@ struct arm_smmu_domain {
>  
>       struct io_pgtable_ops           *pgtbl_ops;
>       bool                            non_strict;
> -     atomic_t                        nr_ats_masters;
>  
>       enum arm_smmu_domain_stage      stage;
>       union {
> @@ -886,14 +874,6 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct 
> arm_smmu_cmdq_ent *ent)
>       case CMDQ_OP_TLBI_S12_VMALL:
>               cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_VMID, ent->tlbi.vmid);
>               break;
> -     case CMDQ_OP_ATC_INV:
> -             cmd[0] |= FIELD_PREP(CMDQ_0_SSV, ent->substream_valid);
> -             cmd[0] |= FIELD_PREP(CMDQ_ATC_0_GLOBAL, ent->atc.global);
> -             cmd[0] |= FIELD_PREP(CMDQ_ATC_0_SSID, ent->atc.ssid);
> -             cmd[0] |= FIELD_PREP(CMDQ_ATC_0_SID, ent->atc.sid);
> -             cmd[1] |= FIELD_PREP(CMDQ_ATC_1_SIZE, ent->atc.size);
> -             cmd[1] |= ent->atc.addr & CMDQ_ATC_1_ADDR_MASK;
> -             break;
>       case CMDQ_OP_PRI_RESP:
>               cmd[0] |= FIELD_PREP(CMDQ_0_SSV, ent->substream_valid);
>               cmd[0] |= FIELD_PREP(CMDQ_PRI_0_SSID, ent->pri.ssid);
> @@ -925,7 +905,6 @@ static void arm_smmu_cmdq_skip_err(struct arm_smmu_device 
> *smmu)
>               [CMDQ_ERR_CERROR_NONE_IDX]      = "No error",
>               [CMDQ_ERR_CERROR_ILL_IDX]       = "Illegal command",
>               [CMDQ_ERR_CERROR_ABT_IDX]       = "Abort on command fetch",
> -             [CMDQ_ERR_CERROR_ATC_INV_IDX]   = "ATC invalidate timeout",
>       };
>  
>       int i;
> @@ -945,14 +924,6 @@ static void arm_smmu_cmdq_skip_err(struct 
> arm_smmu_device *smmu)
>               dev_err(smmu->dev, "retrying command fetch\n");
>       case CMDQ_ERR_CERROR_NONE_IDX:
>               return;
> -     case CMDQ_ERR_CERROR_ATC_INV_IDX:
> -             /*
> -              * ATC Invalidation Completion timeout. CONS is still pointing
> -              * at the CMD_SYNC. Attempt to complete other pending commands
> -              * by repeating the CMD_SYNC, though we might well end up back
> -              * here since the ATC invalidation may still be pending.
> -              */
> -             return;
>       case CMDQ_ERR_CERROR_ILL_IDX:
>       default:
>               break;
> @@ -1422,9 +1393,6 @@ static void arm_smmu_write_strtab_ent(struct 
> arm_smmu_master *master, u32 sid,
>               val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_S2_TRANS);
>       }
>  
> -     if (master->ats_enabled)
> -             dst[1] |= cpu_to_le64(FIELD_PREP(STRTAB_STE_1_EATS,
> -                                              STRTAB_STE_1_EATS_TRANS));
>  
>       arm_smmu_sync_ste_for_sid(smmu, sid);
>       /* See comment in arm_smmu_write_ctx_desc() */
> @@ -1633,112 +1601,6 @@ static irqreturn_t arm_smmu_combined_irq_handler(int 
> irq, void *dev)
>       return IRQ_WAKE_THREAD;
>  }
>  
> -static void
> -arm_smmu_atc_inv_to_cmd(int ssid, unsigned long iova, size_t size,
> -                     struct arm_smmu_cmdq_ent *cmd)
> -{
> -     size_t log2_span;
> -     size_t span_mask;
> -     /* ATC invalidates are always on 4096-bytes pages */
> -     size_t inval_grain_shift = 12;
> -     unsigned long page_start, page_end;
> -
> -     *cmd = (struct arm_smmu_cmdq_ent) {
> -             .opcode                 = CMDQ_OP_ATC_INV,
> -             .substream_valid        = !!ssid,
> -             .atc.ssid               = ssid,
> -     };
> -
> -     if (!size) {
> -             cmd->atc.size = ATC_INV_SIZE_ALL;
> -             return;
> -     }
> -
> -     page_start      = iova >> inval_grain_shift;
> -     page_end        = (iova + size - 1) >> inval_grain_shift;
> -
> -     /*
> -      * In an ATS Invalidate Request, the address must be aligned on the
> -      * range size, which must be a power of two number of page sizes. We
> -      * thus have to choose between grossly over-invalidating the region, or
> -      * splitting the invalidation into multiple commands. For simplicity
> -      * we'll go with the first solution, but should refine it in the future
> -      * if multiple commands are shown to be more efficient.
> -      *
> -      * Find the smallest power of two that covers the range. The most
> -      * significant differing bit between the start and end addresses,
> -      * fls(start ^ end), indicates the required span. For example:
> -      *
> -      * We want to invalidate pages [8; 11]. This is already the ideal range:
> -      *              x = 0b1000 ^ 0b1011 = 0b11
> -      *              span = 1 << fls(x) = 4
> -      *
> -      * To invalidate pages [7; 10], we need to invalidate [0; 15]:
> -      *              x = 0b0111 ^ 0b1010 = 0b1101
> -      *              span = 1 << fls(x) = 16
> -      */
> -     log2_span       = fls_long(page_start ^ page_end);
> -     span_mask       = (1ULL << log2_span) - 1;
> -
> -     page_start      &= ~span_mask;
> -
> -     cmd->atc.addr   = page_start << inval_grain_shift;
> -     cmd->atc.size   = log2_span;
> -}
> -
> -static int arm_smmu_atc_inv_master(struct arm_smmu_master *master,
> -                                struct arm_smmu_cmdq_ent *cmd)
> -{
> -     int i;
> -
> -     if (!master->ats_enabled)
> -             return 0;
> -
> -     for (i = 0; i < master->num_sids; i++) {
> -             cmd->atc.sid = master->sids[i];
> -             arm_smmu_cmdq_issue_cmd(master->smmu, cmd);
> -     }
> -
> -     return arm_smmu_cmdq_issue_sync(master->smmu);
> -}
> -
> -static int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain,
> -                                int ssid, unsigned long iova, size_t size)
> -{
> -     int ret = 0;
> -     unsigned long flags;
> -     struct arm_smmu_cmdq_ent cmd;
> -     struct arm_smmu_master *master;
> -
> -     if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_ATS))
> -             return 0;
> -
> -     /*
> -      * Ensure that we've completed prior invalidation of the main TLBs
> -      * before we read 'nr_ats_masters' in case of a concurrent call to
> -      * arm_smmu_enable_ats():
> -      *
> -      *      // unmap()                      // arm_smmu_enable_ats()
> -      *      TLBI+SYNC                       atomic_inc(&nr_ats_masters);
> -      *      smp_mb();                       [...]
> -      *      atomic_read(&nr_ats_masters);   pci_enable_ats() // writel()
> -      *
> -      * Ensures that we always see the incremented 'nr_ats_masters' count if
> -      * ATS was enabled at the PCI device before completion of the TLBI.
> -      */
> -     smp_mb();
> -     if (!atomic_read(&smmu_domain->nr_ats_masters))
> -             return 0;
> -
> -     arm_smmu_atc_inv_to_cmd(ssid, iova, size, &cmd);
> -
> -     spin_lock_irqsave(&smmu_domain->devices_lock, flags);
> -     list_for_each_entry(master, &smmu_domain->devices, domain_head)
> -             ret |= arm_smmu_atc_inv_master(master, &cmd);
> -     spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
> -
> -     return ret ? -ETIMEDOUT : 0;
> -}
>  
>  /* IO_PGTABLE API */
>  static void arm_smmu_tlb_inv_context(void *cookie)
> @@ -1765,7 +1627,6 @@ static void arm_smmu_tlb_inv_context(void *cookie)
>        */
>       arm_smmu_cmdq_issue_cmd(smmu, &cmd);
>       arm_smmu_cmdq_issue_sync(smmu);
> -     arm_smmu_atc_inv_domain(smmu_domain, 0, 0, 0);
>  }
>  
>  static void arm_smmu_tlb_inv_range_nosync(unsigned long iova, size_t size,
> @@ -2106,108 +1967,6 @@ static void arm_smmu_install_ste_for_dev(struct 
> arm_smmu_master *master)
>       }
>  }
>  
> -static bool arm_smmu_ats_supported(struct arm_smmu_master *master)
> -{
> -     struct device *dev = master->dev;
> -     struct arm_smmu_device *smmu = master->smmu;
> -     struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> -
> -     if (!(smmu->features & ARM_SMMU_FEAT_ATS))
> -             return false;
> -
> -     if (!(fwspec->flags & IOMMU_FWSPEC_PCI_RC_ATS))
> -             return false;
> -
> -     return dev_is_pci(dev) && pci_ats_supported(to_pci_dev(dev));
> -}
> -
> -static void arm_smmu_enable_ats(struct arm_smmu_master *master)
> -{
> -     size_t stu;
> -     struct pci_dev *pdev;
> -     struct arm_smmu_device *smmu = master->smmu;
> -     struct arm_smmu_domain *smmu_domain = master->domain;
> -
> -     /* Don't enable ATS at the endpoint if it's not enabled in the STE */
> -     if (!master->ats_enabled)
> -             return;
> -
> -     /* Smallest Translation Unit: log2 of the smallest supported granule */
> -     stu = __ffs(smmu->pgsize_bitmap);
> -     pdev = to_pci_dev(master->dev);
> -
> -     atomic_inc(&smmu_domain->nr_ats_masters);
> -     arm_smmu_atc_inv_domain(smmu_domain, 0, 0, 0);
> -     if (pci_enable_ats(pdev, stu))
> -             dev_err(master->dev, "Failed to enable ATS (STU %zu)\n", stu);
> -}
> -
> -static void arm_smmu_disable_ats(struct arm_smmu_master *master)
> -{
> -     struct arm_smmu_cmdq_ent cmd;
> -     struct arm_smmu_domain *smmu_domain = master->domain;
> -
> -     if (!master->ats_enabled)
> -             return;
> -
> -     pci_disable_ats(to_pci_dev(master->dev));
> -     /*
> -      * Ensure ATS is disabled at the endpoint before we issue the
> -      * ATC invalidation via the SMMU.
> -      */
> -     wmb();
> -     arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
> -     arm_smmu_atc_inv_master(master, &cmd);
> -    atomic_dec(&smmu_domain->nr_ats_masters);
> -}
> -
> -static int arm_smmu_enable_pasid(struct arm_smmu_master *master)
> -{
> -     int ret;
> -     int features;
> -     int num_pasids;
> -     struct pci_dev *pdev;
> -
> -     if (!dev_is_pci(master->dev))
> -             return -ENODEV;
> -
> -     pdev = to_pci_dev(master->dev);
> -
> -     features = pci_pasid_features(pdev);
> -     if (features < 0)
> -             return features;
> -
> -     num_pasids = pci_max_pasids(pdev);
> -     if (num_pasids <= 0)
> -             return num_pasids;
> -
> -     ret = pci_enable_pasid(pdev, features);
> -     if (ret) {
> -             dev_err(&pdev->dev, "Failed to enable PASID\n");
> -             return ret;
> -     }
> -
> -     master->ssid_bits = min_t(u8, ilog2(num_pasids),
> -                               master->smmu->ssid_bits);
> -     return 0;
> -}
> -
> -static void arm_smmu_disable_pasid(struct arm_smmu_master *master)
> -{
> -     struct pci_dev *pdev;
> -
> -     if (!dev_is_pci(master->dev))
> -             return;
> -
> -     pdev = to_pci_dev(master->dev);
> -
> -     if (!pdev->pasid_enabled)
> -             return;
> -
> -     master->ssid_bits = 0;
> -     pci_disable_pasid(pdev);
> -}
> -
>  static void arm_smmu_detach_dev(struct arm_smmu_master *master)
>  {
>       unsigned long flags;
> @@ -2216,14 +1975,11 @@ static void arm_smmu_detach_dev(struct 
> arm_smmu_master *master)
>       if (!smmu_domain)
>               return;
>  
> -     arm_smmu_disable_ats(master);
> -
>       spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>       list_del(&master->domain_head);
>       spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
>  
>       master->domain = NULL;
> -     master->ats_enabled = false;
>       arm_smmu_install_ste_for_dev(master);
>  }
>  
> @@ -2271,17 +2027,12 @@ static int arm_smmu_attach_dev(struct iommu_domain 
> *domain, struct device *dev)
>  
>       master->domain = smmu_domain;
>  
> -     if (smmu_domain->stage != ARM_SMMU_DOMAIN_BYPASS)
> -             master->ats_enabled = arm_smmu_ats_supported(master);
> -
>       arm_smmu_install_ste_for_dev(master);
>  
>       spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>       list_add(&master->domain_head, &smmu_domain->devices);
>       spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
>  
> -     arm_smmu_enable_ats(master);
> -
>  out_unlock:
>       mutex_unlock(&smmu_domain->init_mutex);
>       return ret;
> @@ -2410,16 +2161,6 @@ static struct iommu_device 
> *arm_smmu_probe_device(struct device *dev)
>  
>       master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
>  
> -     /*
> -      * Note that PASID must be enabled before, and disabled after ATS:
> -      * PCI Express Base 4.0r1.0 - 10.5.1.3 ATS Control Register
> -      *
> -      *   Behavior is undefined if this bit is Set and the value of the PASID
> -      *   Enable, Execute Requested Enable, or Privileged Mode Requested bits
> -      *   are changed.
> -      */
> -     arm_smmu_enable_pasid(master);
> -
>       if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
>               master->ssid_bits = min_t(u8, master->ssid_bits,
>                                         CTXDESC_LINEAR_CDMAX);
> @@ -2442,7 +2183,6 @@ static void arm_smmu_release_device(struct device *dev)
>  
>       master = dev_iommu_priv_get(dev);
>       arm_smmu_detach_dev(master);
> -     arm_smmu_disable_pasid(master);
>       kfree(master);
>       iommu_fwspec_free(dev);
>  }
> @@ -2997,15 +2737,6 @@ static int arm_smmu_device_reset(struct 
> arm_smmu_device *smmu, bool bypass)
>               }
>       }
>  
> -     if (smmu->features & ARM_SMMU_FEAT_ATS) {
> -             enables |= CR0_ATSCHK;
> -             ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0,
> -                                           ARM_SMMU_CR0ACK);
> -             if (ret) {
> -                     dev_err(smmu->dev, "failed to enable ATS check\n");
> -                     return ret;
> -             }
> -     }
>  
>       ret = arm_smmu_setup_irqs(smmu);
>       if (ret) {
> @@ -3076,13 +2807,9 @@ static int arm_smmu_device_hw_probe(struct 
> arm_smmu_device *smmu)
>       if (IS_ENABLED(CONFIG_PCI_PRI) && reg & IDR0_PRI)
>               smmu->features |= ARM_SMMU_FEAT_PRI;
>  
> -     if (IS_ENABLED(CONFIG_PCI_ATS) && reg & IDR0_ATS)
> -             smmu->features |= ARM_SMMU_FEAT_ATS;
> -
>       if (reg & IDR0_SEV)
>               smmu->features |= ARM_SMMU_FEAT_SEV;
>  
> -
>       if (reg & IDR0_HYP)

spurious change



 


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