Re: [PATCH v1 12/14] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED type of allocations

Eric Auger
2023-03-24T15:46:52Z

Hi Nicolin,

On 3/9/23 11:53, Nicolin Chen wrote:
> Add domain allocation support for IOMMU_DOMAIN_NESTED type. This includes
> the "finalise" part to log in the user space Stream Table Entry info.

Please explain the domain ops specialization.
>
> Co-developed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 38 +++++++++++++++++++--
> 1 file changed, 36 insertions(+), 2 deletions(-)
>
> 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 5ff74edfbd68..1f318b5e0921 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2214,6 +2214,19 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
> return 0;
> }
>
> + if (domain->type == IOMMU_DOMAIN_NESTED) {
> + if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1) ||
> + !(smmu->features & ARM_SMMU_FEAT_TRANS_S2)) {
> + dev_dbg(smmu->dev, "does not implement two stages\n");
> + return -EINVAL;
> + }
> + smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> + smmu_domain->s1_cfg.s1fmt = user_cfg->s1fmt;
> + smmu_domain->s1_cfg.s1cdmax = user_cfg->s1cdmax;
> + smmu_domain->s1_cfg.cdcfg.cdtab_dma = user_cfg->s1ctxptr;
> + return 0;
> + }
> +
> if (user_cfg_s2 && !(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
> return -EINVAL;
> if (user_cfg_s2)
> @@ -2863,6 +2876,11 @@ static void arm_smmu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
> arm_smmu_sva_remove_dev_pasid(domain, dev, pasid);
> }
>
> +static const struct iommu_domain_ops arm_smmu_nested_domain_ops = {
> + .attach_dev = arm_smmu_attach_dev,
> + .free = arm_smmu_domain_free,
> +};
> +
> static struct iommu_domain *
> __arm_smmu_domain_alloc(unsigned type,
> struct arm_smmu_domain *s2,
> @@ -2877,11 +2895,15 @@ __arm_smmu_domain_alloc(unsigned type,
> return arm_smmu_sva_domain_alloc();
>
> if (type != IOMMU_DOMAIN_UNMANAGED &&
> + type != IOMMU_DOMAIN_NESTED &&
> type != IOMMU_DOMAIN_DMA &&
> type != IOMMU_DOMAIN_DMA_FQ &&
> type != IOMMU_DOMAIN_IDENTITY)
> return NULL;
>
> + if (s2 && s2->stage != ARM_SMMU_DOMAIN_S2)
> + return NULL;
> +
> /*
> * Allocate the domain and initialise some of its data structures.
> * We can't really finalise the domain unless a master is given.
> @@ -2889,10 +2911,14 @@ __arm_smmu_domain_alloc(unsigned type,
> smmu_domain = kzalloc(sizeof(*smmu_domain), GFP_KERNEL);
> if (!smmu_domain)
> return NULL;
> + smmu_domain->s2 = s2;
> domain = &smmu_domain->domain;
>
> domain->type = type;
> - domain->ops = arm_smmu_ops.default_domain_ops;
> + if (s2)
> + domain->ops = &arm_smmu_nested_domain_ops;
> + else
> + domain->ops = arm_smmu_ops.default_domain_ops;
>
> mutex_init(&smmu_domain->init_mutex);
> INIT_LIST_HEAD(&smmu_domain->devices);
> @@ -2923,8 +2949,16 @@ arm_smmu_domain_alloc_user(struct device *dev, struct iommu_domain *parent,
> const struct iommu_hwpt_arm_smmuv3 *user_cfg = user_data;
> struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> unsigned type = IOMMU_DOMAIN_UNMANAGED;
> + struct arm_smmu_domain *s2 = NULL;
> +
> + if (parent) {
> + if (parent->ops != arm_smmu_ops.default_domain_ops)
> + return NULL;
> + type = IOMMU_DOMAIN_NESTED;
> + s2 = to_smmu_domain(parent);
> + }
Please can you explain the (use) case where !parent. This creates an
unmanaged S1?

Thanks

Eric
>
> - return __arm_smmu_domain_alloc(type, NULL, master, user_cfg);
> + return __arm_smmu_domain_alloc(type, s2, master, user_cfg);
> }
>
> static struct iommu_ops arm_smmu_ops = {