Re: [PATCH v7 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster
From: Pranjal Shrivastava <praan@google.com>
Date: 2025-02-24 20:36:08
Also in:
linux-arm-kernel, linux-iommu, linux-kselftest, linux-patches, lkml
oN sAt, Feb 22, 2025 at 07:54:09AM -0800, Nicolin Chen wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c index 5aa2e7af58b4..364d8469a480 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c@@ -85,6 +85,59 @@ static void arm_smmu_make_nested_domain_ste( } } +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state, + struct iommu_domain *domain) +{ + struct arm_smmu_nested_domain *nested_domain; + struct arm_smmu_vmaster *vmaster; + unsigned long vsid; + int ret; + + iommu_group_mutex_assert(state->master->dev); + + if (domain->type != IOMMU_DOMAIN_NESTED) + return 0; + nested_domain = to_smmu_nested_domain(domain); + + /* Skip invalid vSTE */ + if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V))) + return 0; + + ret = iommufd_viommu_get_vdev_id(&nested_domain->vsmmu->core, + state->master->dev, &vsid); + if (ret) + return ret; + + vmaster = kzalloc(sizeof(*vmaster), GFP_KERNEL); + if (!vmaster) + return -ENOMEM; + vmaster->vsmmu = nested_domain->vsmmu; + vmaster->vsid = vsid; + state->vmaster = vmaster; + + return 0; +} + +void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state) +{ + struct arm_smmu_master *master = state->master; + + mutex_lock(&master->smmu->streams_mutex); + if (state->vmaster != master->vmaster) { + kfree(master->vmaster); + master->vmaster = state->vmaster; + }
Does this condition suggest that we might end up calling `arm_smmu_attach_prepare_vmaster()` multiple times before __actually__ commiting to a vmaster?
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+ mutex_unlock(&master->smmu->streams_mutex); +} + +void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master) +{ + mutex_lock(&master->smmu->streams_mutex); + kfree(master->vmaster); + master->vmaster = NULL; + mutex_unlock(&master->smmu->streams_mutex); +} + static int arm_smmu_attach_dev_nested(struct iommu_domain *domain, struct device *dev) {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 358072b4e293..9e50bcee69d1 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -2803,6 +2803,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, struct arm_smmu_domain *smmu_domain = to_smmu_domain_devices(new_domain); unsigned long flags; + int ret; /* * arm_smmu_share_asid() must not see two domains pointing to the same@@ -2832,9 +2833,15 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, } if (smmu_domain) { + ret = arm_smmu_attach_prepare_vmaster(state, new_domain);
IMO, this adds a little confusion for folks not using iommufd. I guess it'd be cleaner if we invoke this below within the: `if (new_domain->type == IOMMU_DOMAIN_NESTED)` condition instead of simply returning from the function if the new_domain->type isn't NESTED.
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+ if (ret) + return ret; + master_domain = kzalloc(sizeof(*master_domain), GFP_KERNEL); - if (!master_domain) + if (!master_domain) { + kfree(state->vmaster); return -ENOMEM; + } master_domain->master = master; master_domain->ssid = state->ssid; if (new_domain->type == IOMMU_DOMAIN_NESTED)@@ -2861,6 +2868,7 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state, spin_unlock_irqrestore(&smmu_domain->devices_lock, flags); kfree(master_domain); + kfree(state->vmaster); return -EINVAL; }@@ -2893,6 +2901,8 @@ void arm_smmu_attach_commit(struct arm_smmu_attach_state *state) lockdep_assert_held(&arm_smmu_asid_lock); + arm_smmu_attach_commit_vmaster(state); + if (state->ats_enabled && !master->ats_enabled) { arm_smmu_enable_ats(master); } else if (state->ats_enabled && master->ats_enabled) {@@ -3162,6 +3172,7 @@ static int arm_smmu_attach_dev_identity(struct iommu_domain *domain, struct arm_smmu_ste ste; struct arm_smmu_master *master = dev_iommu_priv_get(dev); + arm_smmu_master_clear_vmaster(master); arm_smmu_make_bypass_ste(master->smmu, &ste); arm_smmu_attach_dev_ste(domain, dev, &ste, STRTAB_STE_1_S1DSS_BYPASS); return 0;@@ -3180,7 +3191,9 @@ static int arm_smmu_attach_dev_blocked(struct iommu_domain *domain, struct device *dev) { struct arm_smmu_ste ste; + struct arm_smmu_master *master = dev_iommu_priv_get(dev); + arm_smmu_master_clear_vmaster(master); arm_smmu_make_abort_ste(&ste); arm_smmu_attach_dev_ste(domain, dev, &ste, STRTAB_STE_1_S1DSS_TERMINATE);
Thanks, Praan