Hello Julien,
> On 11 Dec 2020, at 2:25 pm, Julien Grall <[email protected]> wrote:
>
> Hi Rahul,
>
> On 10/12/2020 16:57, Rahul Singh wrote:
>> struct arm_smmu_strtab_cfg {
>> @@ -613,8 +847,13 @@ struct arm_smmu_device {
>> u64 padding;
>> };
>> - /* IOMMU core code handle */
>> - struct iommu_device iommu;
>> + /* Need to keep a list of SMMU devices */
>> + struct list_head devices;
>> +
>> + /* Tasklets for handling evts/faults and pci page request IRQs*/
>> + struct tasklet evtq_irq_tasklet;
>> + struct tasklet priq_irq_tasklet;
>> + struct tasklet combined_irq_tasklet;
>> };
>> /* SMMU private data for each master */
>> @@ -638,7 +877,6 @@ enum arm_smmu_domain_stage {
>> struct arm_smmu_domain {
>> struct arm_smmu_device *smmu;
>> - struct mutex init_mutex; /* Protects smmu pointer */
>
> Hmmm... Your commit message says the mutex would be replaced by a spinlock.
> However, you are dropping the lock. What I did miss?
Linux code using the mutex in the function arm_smmu_attach_dev() but in XEN
this function is called from arm_smmu_assign_dev() which already has the
spin_lock when arm_smmu_attach_dev() function I called so I drop the mutex to
avoid nested spinlock.
Timing analysis of using spin lock in place of mutex as compared to linux when
attaching a device to SMMU is still valid.
>
> [...]
>
>> @@ -1578,6 +1841,17 @@ static int arm_smmu_domain_finalise_s2(struct
>> arm_smmu_domain *smmu_domain,
>> struct arm_smmu_device *smmu = smmu_domain->smmu;
>> struct arm_smmu_s2_cfg *cfg = &smmu_domain->s2_cfg;
>> typeof(&arm_lpae_s2_cfg.vtcr) vtcr = &arm_lpae_s2_cfg.vtcr;
>> + uint64_t reg = READ_SYSREG64(VTCR_EL2);
>
> Please don't use VTCR_EL2 here. You should be able to infer the parameter
> from the p2m_ipa_bits.
Ok.
>
> Also, I still don't see code that will restrict the IPA bits because on the
> support for the SMMU.
Ok I will add the code to restrict the IPA bits in next version.
>
>> +
>> + vtcr->tsz = FIELD_GET(STRTAB_STE_2_VTCR_S2T0SZ, reg);
>> + vtcr->sl = FIELD_GET(STRTAB_STE_2_VTCR_S2SL0, reg);
>> + vtcr->irgn = FIELD_GET(STRTAB_STE_2_VTCR_S2IR0, reg);
>> + vtcr->orgn = FIELD_GET(STRTAB_STE_2_VTCR_S2OR0, reg);
>> + vtcr->sh = FIELD_GET(STRTAB_STE_2_VTCR_S2SH0, reg);
>> + vtcr->tg = FIELD_GET(STRTAB_STE_2_VTCR_S2TG, reg);
>> + vtcr->ps = FIELD_GET(STRTAB_STE_2_VTCR_S2PS, reg);
>> +
>> + arm_lpae_s2_cfg.vttbr = page_to_maddr(cfg->domain->arch.p2m.root);
>> vmid = arm_smmu_bitmap_alloc(smmu->vmid_map, smmu->vmid_bits);
>> if (vmid < 0)
>> @@ -1592,6 +1866,11 @@ static int arm_smmu_domain_finalise_s2(struct
>> arm_smmu_domain *smmu_domain,
>> FIELD_PREP(STRTAB_STE_2_VTCR_S2SH0, vtcr->sh) |
>> FIELD_PREP(STRTAB_STE_2_VTCR_S2TG, vtcr->tg) |
>> FIELD_PREP(STRTAB_STE_2_VTCR_S2PS, vtcr->ps);
>> +
>> + printk(XENLOG_DEBUG
>> + "SMMUv3: d%u: vmid 0x%x vtcr 0x%"PRIpaddr" p2maddr
>> 0x%"PRIpaddr"\n",
>> + cfg->domain->domain_id, cfg->vmid, cfg->vtcr, cfg->vttbr);
>> +
>> return 0;
>> }
>
> [...]
>
>> @@ -1923,8 +2239,8 @@ static int arm_smmu_init_one_queue(struct
>> arm_smmu_device *smmu,
>> return -ENOMEM;
>> }
>> - if (!WARN_ON(q->base_dma & (qsz - 1))) { > -
>> dev_info(smmu->dev, "allocated %u entries for %s\n",
>> + if (unlikely(q->base_dma & (qsz - 1))) {
>> + dev_warn(smmu->dev, "allocated %u entries for %s\n",
> dev_warn() is not the same as WARN_ON(). But really, the first step is for
> you to try to change behavior of WARN_ON() in Xen.
Ok. I will make sure we have the same behaviour as linux by modifying the code
as below.
WARN_ON(q->base_dma & (qsz - 1));
if (!unlikely(q->base_dma & (qsz - 1))) {
dev_info(smmu->dev, "allocated %u entries for %s\n",
1 << q->llq.max_n_shift, name);
}
Regards,
Rahul
>
> If this doesn't go through then we can discuss about approach to mitigate it.
>
> Cheers,
>
> --
> Julien Grall
