[PATCH v3 06/16] iommu/arm-smmu: Add auxiliary domain support for arm-smmuv2

Jordan Crouse
2019-05-29T20:55:33Z

Support auxiliary domains for arm-smmu-v2 to initialize and support multiple
pagetables for a single SMMU context bank. Since the smmu-v2 hardware
doesn't have any built in support for switching the pagetable base it is
left as an exercise to the caller to actually use the pagetable; aux
domains in the IOMMU driver are only preoccupied with creating and managing
the pagetable memory.

Following is a pseudo code example of how a domain can be created

/* Check to see if aux domains are supported */
if (iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX)) {
iommu = iommu_domain_alloc(...);

if (iommu_aux_attach_device(domain, dev))
return FAIL;

/* Save the base address of the pagetable for use by the driver
iommu_domain_get_attr(domain, DOMAIN_ATTR_PTBASE, &ptbase);
}

Then 'domain' can be used like any other iommu domain to map and
unmap iova addresses in the pagetable. The driver/hardware is used
to switch the pagetable according to its own specific implementation.

v3: Trivial update to reflect new pgtable ops situation

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
---

drivers/iommu/arm-smmu.c | 125 +++++++++++++++++++++++++++++++++++++++++------
1 file changed, 110 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 33e6928..589da47 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -262,6 +262,8 @@ struct arm_smmu_domain {
spinlock_t cb_lock; /* Serialises ATS1* ops and TLB syncs */
u32 attributes;
struct iommu_domain domain;
+ bool is_aux;
+ u64 ttbr0;
};

struct arm_smmu_option_prop {
@@ -803,6 +805,12 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
smmu_domain->stage = ARM_SMMU_DOMAIN_S1;

+ /* Aux domains can only be created for stage-1 tables */
+ if (smmu_domain->is_aux && smmu_domain->stage != ARM_SMMU_DOMAIN_S1) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
/*
* Choosing a suitable context format is even more fiddly. Until we
* grow some way for the caller to express a preference, and/or move
@@ -850,6 +858,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
ias = min(ias, 32UL);
oas = min(oas, 32UL);
}
+
smmu_domain->tlb_ops = &arm_smmu_s1_tlb_ops;
break;
case ARM_SMMU_DOMAIN_NESTED:
@@ -869,6 +878,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
ias = min(ias, 40UL);
oas = min(oas, 40UL);
}
+
if (smmu->version == ARM_SMMU_V2)
smmu_domain->tlb_ops = &arm_smmu_s2_tlb_ops_v2;
else
@@ -878,23 +888,30 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
ret = -EINVAL;
goto out_unlock;
}
- ret = __arm_smmu_alloc_bitmap(smmu->context_map, start,
- smmu->num_context_banks);
- if (ret < 0)
- goto out_unlock;

- cfg->cbndx = ret;
- if (smmu->version < ARM_SMMU_V2) {
- cfg->irptndx = atomic_inc_return(&smmu->irptndx);
- cfg->irptndx %= smmu->num_context_irqs;
- } else {
- cfg->irptndx = cfg->cbndx;
- }
+ /*
+ * Aux domains will use the same context bank assigned to the master
+ * domain for the device
+ */
+ if (!smmu_domain->is_aux) {
+ ret = __arm_smmu_alloc_bitmap(smmu->context_map, start,
+ smmu->num_context_banks);
+ if (ret < 0)
+ goto out_unlock;

- if (smmu_domain->stage == ARM_SMMU_DOMAIN_S2)
- cfg->vmid = cfg->cbndx + 1 + smmu->cavium_id_base;
- else
- cfg->asid = cfg->cbndx + smmu->cavium_id_base;
+ cfg->cbndx = ret;
+ if (smmu->version < ARM_SMMU_V2) {
+ cfg->irptndx = atomic_inc_return(&smmu->irptndx);
+ cfg->irptndx %= smmu->num_context_irqs;
+ } else {
+ cfg->irptndx = cfg->cbndx;
+ }
+
+ if (smmu_domain->stage == ARM_SMMU_DOMAIN_S2)
+ cfg->vmid = cfg->cbndx + 1 + smmu->cavium_id_base;
+ else
+ cfg->asid = cfg->cbndx + smmu->cavium_id_base;
+ }

pgtbl_cfg = (struct io_pgtable_cfg) {
.pgsize_bitmap = smmu->pgsize_bitmap,
@@ -917,11 +934,21 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
goto out_clear_smmu;
}

+ /* Cache the TTBR0 for the aux domain */
+ smmu_domain->ttbr0 = pgtbl_cfg.arm_lpae_s1_cfg.ttbr[0];
+
/* Update the domain's page sizes to reflect the page table format */
domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
domain->geometry.aperture_end = (1UL << ias) - 1;
domain->geometry.force_aperture = true;

+ /*
+ * aux domains don't use split tables or program the hardware so we're
+ * done setting it up
+ */
+ if (smmu_domain->is_aux)
+ goto out;
+
/* Initialise the context bank with our page table cfg */
arm_smmu_init_context_bank(smmu_domain, &pgtbl_cfg);
arm_smmu_write_context_bank(smmu, cfg->cbndx);
@@ -939,6 +966,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
cfg->irptndx = INVALID_IRPTNDX;
}

+out:
mutex_unlock(&smmu_domain->init_mutex);

/* Publish page table ops for map/unmap */
@@ -962,6 +990,12 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain)
if (!smmu || domain->type == IOMMU_DOMAIN_IDENTITY)
return;

+ /* All we need to do for aux devices is destroy the pagetable */
+ if (smmu_domain->is_aux) {
+ free_io_pgtable_ops(smmu_domain->pgtbl_ops);
+ return;
+ }
+
ret = arm_smmu_rpm_get(smmu);
if (ret < 0)
return;
@@ -1242,14 +1276,17 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,

struct arm_smmu_client_match_data {
bool direct_mapping;
+ bool allow_aux_domain;
};

static const struct arm_smmu_client_match_data qcom_adreno = {
.direct_mapping = true,
+ .allow_aux_domain = true,
};

static const struct arm_smmu_client_match_data qcom_mdss = {
.direct_mapping = true,
+ .allow_aux_domain = false,
};

static const struct of_device_id arm_smmu_client_of_match[] = {
@@ -1269,6 +1306,55 @@ arm_smmu_client_data(struct device *dev)
return match ? match->data : NULL;
}

+static bool arm_smmu_supports_aux(struct device *dev)
+{
+ const struct arm_smmu_client_match_data *data =
+ arm_smmu_client_data(dev);
+
+ return (data && data->allow_aux_domain);
+}
+
+static bool arm_smmu_dev_has_feat(struct device *dev,
+ enum iommu_dev_features feat)
+{
+ if (feat != IOMMU_DEV_FEAT_AUX)
+ return false;
+
+ return arm_smmu_supports_aux(dev);
+}
+
+static int arm_smmu_dev_enable_feat(struct device *dev,
+ enum iommu_dev_features feat)
+{
+ /* If supported aux domain support is always "on" */
+ if (feat == IOMMU_DEV_FEAT_AUX && arm_smmu_supports_aux(dev))
+ return 0;
+
+ return -ENODEV;
+}
+
+static int arm_smmu_dev_disable_feat(struct device *dev,
+ enum iommu_dev_features feat)
+{
+ return -EBUSY;
+}
+
+/* Set up a new aux domain and create a new pagetable with the same
+ * characteristics as the master
+ */
+static int arm_smmu_aux_attach_dev(struct iommu_domain *domain,
+ struct device *dev)
+{
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+ struct arm_smmu_device *smmu = fwspec_smmu(fwspec);
+ struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+
+ smmu_domain->is_aux = true;
+
+ /* No power is needed because aux domain doesn't touch the hardware */
+ return arm_smmu_init_domain_context(domain, smmu);
+}
+
static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
{
int ret;
@@ -1631,6 +1717,11 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
*(int *)data = !!(smmu_domain->attributes &
(1 << DOMAIN_ATTR_SPLIT_TABLES));
return 0;
+ case DOMAIN_ATTR_PTBASE:
+ if (!smmu_domain->is_aux)
+ return -ENODEV;
+ *((u64 *)data) = smmu_domain->ttbr0;
+ return 0;
default:
return -ENODEV;
}
@@ -1741,7 +1832,11 @@ static struct iommu_ops arm_smmu_ops = {
.capable = arm_smmu_capable,
.domain_alloc = arm_smmu_domain_alloc,
.domain_free = arm_smmu_domain_free,
+ .dev_has_feat = arm_smmu_dev_has_feat,
+ .dev_enable_feat = arm_smmu_dev_enable_feat,
+ .dev_disable_feat = arm_smmu_dev_disable_feat,
.attach_dev = arm_smmu_attach_dev,
+ .aux_attach_dev = arm_smmu_aux_attach_dev,
.map = arm_smmu_map,
.unmap = arm_smmu_unmap,
.flush_iotlb_all = arm_smmu_flush_iotlb_all,
--
2.7.4