On Mon, Feb 24, 2025 at 08:35:56PM +0000, Pranjal Shrivastava wrote:
oN sAt, Feb 22, 2025 at 07:54:09AM -0800, Nicolin Chen wrote:
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?
No. prepare() and commit() are 1:1. How is it interpreted to have "multiple times"?
- 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.
But the arm_smmu_attach_commit_vmaster() still has to be unconditional as !NESTED domain should clean the vamster away..
Nicolin