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    SubjectRe: [PATCH v5 07/12] arm-smmu-v3/sva: Add SVA domain support
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    On 2022/5/4 02:12, Jean-Philippe Brucker wrote:
    > On Mon, May 02, 2022 at 09:48:37AM +0800, Lu Baolu wrote:
    >> Add support for SVA domain allocation and provide an SVA-specific
    >> iommu_domain_ops.
    >>
    >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    >> ---
    >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 14 +++++++
    >> .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 42 +++++++++++++++++++
    >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 21 ++++++++++
    >> 3 files changed, 77 insertions(+)
    >>
    >> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
    >> index cd48590ada30..7631c00fdcbd 100644
    >> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
    >> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
    >> @@ -759,6 +759,10 @@ struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
    >> void arm_smmu_sva_unbind(struct iommu_sva *handle);
    >> u32 arm_smmu_sva_get_pasid(struct iommu_sva *handle);
    >> void arm_smmu_sva_notifier_synchronize(void);
    >> +int arm_smmu_sva_attach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev, ioasid_t id);
    >> +void arm_smmu_sva_detach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev, ioasid_t id);
    >> #else /* CONFIG_ARM_SMMU_V3_SVA */
    >> static inline bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
    >> {
    >> @@ -804,5 +808,15 @@ static inline u32 arm_smmu_sva_get_pasid(struct iommu_sva *handle)
    >> }
    >>
    >> static inline void arm_smmu_sva_notifier_synchronize(void) {}
    >> +
    >> +static inline int arm_smmu_sva_attach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev, ioasid_t id)
    >> +{
    >> + return -ENODEV;
    >> +}
    >> +
    >> +static inline void arm_smmu_sva_detach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev,
    >> + ioasid_t id) {}
    >> #endif /* CONFIG_ARM_SMMU_V3_SVA */
    >> #endif /* _ARM_SMMU_V3_H */
    >> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
    >> index c623dae1e115..3b843cd3ed67 100644
    >> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
    >> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
    >> @@ -541,3 +541,45 @@ void arm_smmu_sva_notifier_synchronize(void)
    >> */
    >> mmu_notifier_synchronize();
    >> }
    >> +
    >> +int arm_smmu_sva_attach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev, ioasid_t id)
    >> +{
    >> + int ret = 0;
    >> + struct iommu_sva *handle;
    >> + struct mm_struct *mm = iommu_sva_domain_mm(domain);
    >> +
    >> + if (domain->type != IOMMU_DOMAIN_SVA || !mm)
    >
    > We wouldn't get that far with a non-SVA domain since iommu_sva_domain_mm()
    > would dereference a NULL pointer. Could you move it after the domain->type
    > check, and maybe add a WARN_ON()? It could help catch issues in future
    > API changes.

    Sure. I will make it like this,

    int arm_smmu_sva_attach_dev_pasid(struct iommu_domain *domain,
    struct device *dev, ioasid_t id)
    {
    int ret = 0;
    struct mm_struct *mm;
    struct iommu_sva *handle;

    if (domain->type != IOMMU_DOMAIN_SVA)
    return -EINVAL;

    mm = iommu_sva_domain_mm(domain);
    if (WARN_ON(!mm))
    return -ENODEV;
    ... ...

    >
    >> + return -EINVAL;
    >> +
    >> + mutex_lock(&sva_lock);
    >> + handle = __arm_smmu_sva_bind(dev, mm);
    >> + if (IS_ERR(handle))
    >> + ret = PTR_ERR(handle);
    >> + mutex_unlock(&sva_lock);
    >> +
    >> + return ret;
    >> +}
    >> +
    >> +void arm_smmu_sva_detach_dev_pasid(struct iommu_domain *domain,
    >> + struct device *dev, ioasid_t id)
    >> +{
    >> + struct arm_smmu_bond *bond = NULL, *t;
    >> + struct mm_struct *mm = iommu_sva_domain_mm(domain);
    >> + struct arm_smmu_master *master = dev_iommu_priv_get(dev);
    >> +
    >> + mutex_lock(&sva_lock);
    >> + list_for_each_entry(t, &master->bonds, list) {
    >> + if (t->mm == mm) {
    >> + bond = t;
    >> + break;
    >> + }
    >> + }
    >> +
    >> + if (!WARN_ON(!bond) && refcount_dec_and_test(&bond->refs)) {
    >> + list_del(&bond->list);
    >> + arm_smmu_mmu_notifier_put(bond->smmu_mn);
    >> + kfree(bond);
    >> + }
    >> + mutex_unlock(&sva_lock);
    >> +}
    >> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
    >> index afc63fce6107..bd80de0bad98 100644
    >> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
    >> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
    >> @@ -1995,10 +1995,31 @@ static bool arm_smmu_capable(enum iommu_cap cap)
    >> }
    >> }
    >>
    >> +static void arm_smmu_sva_domain_free(struct iommu_domain *domain)
    >> +{
    >> + kfree(domain);
    >> +}
    >> +
    >> +static const struct iommu_domain_ops arm_smmu_sva_domain_ops = {
    >> + .attach_dev_pasid = arm_smmu_sva_attach_dev_pasid,
    >> + .detach_dev_pasid = arm_smmu_sva_detach_dev_pasid,
    >> + .free = arm_smmu_sva_domain_free,
    >> +};
    >> +
    >> static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
    >> {
    >> struct arm_smmu_domain *smmu_domain;
    >>
    >> + if (type == IOMMU_DOMAIN_SVA) {
    >> + struct iommu_domain *domain;
    >> +
    >> + domain = kzalloc(sizeof(*domain), GFP_KERNEL);
    >> + if (domain)
    >> + domain->ops = &arm_smmu_sva_domain_ops;
    >> +
    >> + return domain;
    >> + }
    >> +
    >
    > I'd prefer moving all of this to arm-smmu-v3-sva.c and just call
    > arm_smmu_sva_domain_alloc() here

    Sure.

    >
    > Otherwise the patch looks fine. I'll rework the driver when I find some
    > time, because we can now remove arm_smmu_bond and move smmu_mn to the SVA
    > domain, maybe also remove sva_lock but I haven't thought it through.

    Yes. Intel SVA code also needs further cleanup. It's in my non-urgent
    task list.

    >
    > Thanks,
    > Jean
    >
    >> if (type != IOMMU_DOMAIN_UNMANAGED &&
    >> type != IOMMU_DOMAIN_DMA &&
    >> type != IOMMU_DOMAIN_DMA_FQ &&
    >> --
    >> 2.25.1
    >>

    Best regards,
    baolu

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