[PATCH v4 09/12] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED

Jason Gunthorpe
2024-10-31T00:21:11Z

For SMMUv3 a IOMMU_DOMAIN_NESTED is composed of a S2 iommu_domain acting
as the parent and a user provided STE fragment that defines the CD table
and related data with addresses translated by the S2 iommu_domain.

The kernel only permits userspace to control certain allowed bits of the
STE that are safe for user/guest control.

IOTLB maintenance is a bit subtle here, the S1 implicitly includes the S2
translation, but there is no way of knowing which S1 entries refer to a
range of S2.

For the IOTLB we follow ARM's guidance and issue a CMDQ_OP_TLBI_NH_ALL to
flush all ASIDs from the VMID after flushing the S2 on any change to the
S2.

The IOMMU_DOMAIN_NESTED can only be created from inside a VIOMMU as the
invalidation path relies on the VIOMMU to translate virtual stream ID used
in the invalidation commands for the CD table and ATS.

Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Donald Dutile <ddutile@redhat.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
.../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 157 ++++++++++++++++++
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 17 +-
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 26 +++
include/uapi/linux/iommufd.h | 20 +++
4 files changed, 219 insertions(+), 1 deletion(-)

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 60dd9e90759571..0b9fffc5b2f09b 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
@@ -30,7 +30,164 @@ void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type)
return info;
}

+static void arm_smmu_make_nested_cd_table_ste(
+ struct arm_smmu_ste *target, struct arm_smmu_master *master,
+ struct arm_smmu_nested_domain *nested_domain, bool ats_enabled)
+{
+ arm_smmu_make_s2_domain_ste(
+ target, master, nested_domain->vsmmu->s2_parent, ats_enabled);
+
+ target->data[0] = cpu_to_le64(STRTAB_STE_0_V |
+ FIELD_PREP(STRTAB_STE_0_CFG,
+ STRTAB_STE_0_CFG_NESTED));
+ target->data[0] |= nested_domain->ste[0] &
+ ~cpu_to_le64(STRTAB_STE_0_CFG);
+ target->data[1] |= nested_domain->ste[1];
+}
+
+/*
+ * Create a physical STE from the virtual STE that userspace provided when it
+ * created the nested domain. Using the vSTE userspace can request:
+ * - Non-valid STE
+ * - Abort STE
+ * - Bypass STE (install the S2, no CD table)
+ * - CD table STE (install the S2 and the userspace CD table)
+ */
+static void arm_smmu_make_nested_domain_ste(
+ struct arm_smmu_ste *target, struct arm_smmu_master *master,
+ struct arm_smmu_nested_domain *nested_domain, bool ats_enabled)
+{
+ unsigned int cfg =
+ FIELD_GET(STRTAB_STE_0_CFG, le64_to_cpu(nested_domain->ste[0]));
+
+ /*
+ * Userspace can request a non-valid STE through the nesting interface.
+ * We relay that into an abort physical STE with the intention that
+ * C_BAD_STE for this SID can be generated to userspace.
+ */
+ if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V)))
+ cfg = STRTAB_STE_0_CFG_ABORT;
+
+ switch (cfg) {
+ case STRTAB_STE_0_CFG_S1_TRANS:
+ arm_smmu_make_nested_cd_table_ste(target, master, nested_domain,
+ ats_enabled);
+ break;
+ case STRTAB_STE_0_CFG_BYPASS:
+ arm_smmu_make_s2_domain_ste(target, master,
+ nested_domain->vsmmu->s2_parent,
+ ats_enabled);
+ break;
+ case STRTAB_STE_0_CFG_ABORT:
+ default:
+ arm_smmu_make_abort_ste(target);
+ break;
+ }
+}
+
+static int arm_smmu_attach_dev_nested(struct iommu_domain *domain,
+ struct device *dev)
+{
+ struct arm_smmu_nested_domain *nested_domain =
+ to_smmu_nested_domain(domain);
+ struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+ struct arm_smmu_attach_state state = {
+ .master = master,
+ .old_domain = iommu_get_domain_for_dev(dev),
+ .ssid = IOMMU_NO_PASID,
+ /* Currently invalidation of ATC is not supported */
+ .disable_ats = true,
+ };
+ struct arm_smmu_ste ste;
+ int ret;
+
+ if (nested_domain->vsmmu->smmu != master->smmu)
+ return -EINVAL;
+ if (arm_smmu_ssids_in_use(&master->cd_table))
+ return -EBUSY;
+
+ mutex_lock(&arm_smmu_asid_lock);
+ ret = arm_smmu_attach_prepare(&state, domain);
+ if (ret) {
+ mutex_unlock(&arm_smmu_asid_lock);
+ return ret;
+ }
+
+ arm_smmu_make_nested_domain_ste(&ste, master, nested_domain,
+ state.ats_enabled);
+ arm_smmu_install_ste_for_dev(master, &ste);
+ arm_smmu_attach_commit(&state);
+ mutex_unlock(&arm_smmu_asid_lock);
+ return 0;
+}
+
+static void arm_smmu_domain_nested_free(struct iommu_domain *domain)
+{
+ kfree(to_smmu_nested_domain(domain));
+}
+
+static const struct iommu_domain_ops arm_smmu_nested_ops = {
+ .attach_dev = arm_smmu_attach_dev_nested,
+ .free = arm_smmu_domain_nested_free,
+};
+
+static int arm_smmu_validate_vste(struct iommu_hwpt_arm_smmuv3 *arg)
+{
+ unsigned int cfg;
+
+ if (!(arg->ste[0] & cpu_to_le64(STRTAB_STE_0_V))) {
+ memset(arg->ste, 0, sizeof(arg->ste));
+ return 0;
+ }
+
+ /* EIO is reserved for invalid STE data. */
+ if ((arg->ste[0] & ~STRTAB_STE_0_NESTING_ALLOWED) ||
+ (arg->ste[1] & ~STRTAB_STE_1_NESTING_ALLOWED))
+ return -EIO;
+
+ cfg = FIELD_GET(STRTAB_STE_0_CFG, le64_to_cpu(arg->ste[0]));
+ if (cfg != STRTAB_STE_0_CFG_ABORT && cfg != STRTAB_STE_0_CFG_BYPASS &&
+ cfg != STRTAB_STE_0_CFG_S1_TRANS)
+ return -EIO;
+ return 0;
+}
+
+static struct iommu_domain *
+arm_vsmmu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
+ const struct iommu_user_data *user_data)
+{
+ struct arm_vsmmu *vsmmu = container_of(viommu, struct arm_vsmmu, core);
+ struct arm_smmu_nested_domain *nested_domain;
+ struct iommu_hwpt_arm_smmuv3 arg;
+ int ret;
+
+ if (flags)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ ret = iommu_copy_struct_from_user(&arg, user_data,
+ IOMMU_HWPT_DATA_ARM_SMMUV3, ste);
+ if (ret)
+ return ERR_PTR(ret);
+
+ ret = arm_smmu_validate_vste(&arg);
+ if (ret)
+ return ERR_PTR(ret);
+
+ nested_domain = kzalloc(sizeof(*nested_domain), GFP_KERNEL_ACCOUNT);
+ if (!nested_domain)
+ return ERR_PTR(-ENOMEM);
+
+ nested_domain->domain.type = IOMMU_DOMAIN_NESTED;
+ nested_domain->domain.ops = &arm_smmu_nested_ops;
+ nested_domain->vsmmu = vsmmu;
+ nested_domain->ste[0] = arg.ste[0];
+ nested_domain->ste[1] = arg.ste[1] & ~cpu_to_le64(STRTAB_STE_1_EATS);
+
+ return &nested_domain->domain;
+}
+
static const struct iommufd_viommu_ops arm_vsmmu_ops = {
+ .alloc_domain_nested = arm_vsmmu_alloc_domain_nested,
};

struct iommufd_viommu *arm_vsmmu_alloc(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 c425fb923eb3de..53f12b9d78ab21 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -295,6 +295,7 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
case CMDQ_OP_TLBI_NH_ASID:
cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_ASID, ent->tlbi.asid);
fallthrough;
+ case CMDQ_OP_TLBI_NH_ALL:
case CMDQ_OP_TLBI_S12_VMALL:
cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_VMID, ent->tlbi.vmid);
break;
@@ -2230,6 +2231,15 @@ static void arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t size,
}
__arm_smmu_tlb_inv_range(&cmd, iova, size, granule, smmu_domain);

+ if (smmu_domain->nest_parent) {
+ /*
+ * When the S2 domain changes all the nested S1 ASIDs have to be
+ * flushed too.
+ */
+ cmd.opcode = CMDQ_OP_TLBI_NH_ALL;
+ arm_smmu_cmdq_issue_cmd_with_sync(smmu_domain->smmu, &cmd);
+ }
+
/*
* Unfortunately, this can't be leaf-only since we may have
* zapped an entire table.
@@ -2644,6 +2654,8 @@ to_smmu_domain_devices(struct iommu_domain *domain)
if ((domain->type & __IOMMU_DOMAIN_PAGING) ||
domain->type == IOMMU_DOMAIN_SVA)
return to_smmu_domain(domain);
+ if (domain->type == IOMMU_DOMAIN_NESTED)
+ return to_smmu_nested_domain(domain)->vsmmu->s2_parent;
return NULL;
}

@@ -2716,7 +2728,8 @@ int arm_smmu_attach_prepare(struct arm_smmu_attach_state *state,
* enabled if we have arm_smmu_domain, those always have page
* tables.
*/
- state->ats_enabled = arm_smmu_ats_supported(master);
+ state->ats_enabled = !state->disable_ats &&
+ arm_smmu_ats_supported(master);
}

if (smmu_domain) {
@@ -3122,6 +3135,7 @@ arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
goto err_free;
}
smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
+ smmu_domain->nest_parent = true;
}

smmu_domain->domain.type = IOMMU_DOMAIN_UNMANAGED;
@@ -3518,6 +3532,7 @@ static struct iommu_ops arm_smmu_ops = {
.page_response = arm_smmu_page_response,
.def_domain_type = arm_smmu_def_domain_type,
.viommu_alloc = arm_vsmmu_alloc,
+ .user_pasid_table = 1,
.pgsize_bitmap = -1UL, /* Restricted during device attach */
.owner = THIS_MODULE,
.default_domain_ops = &(const struct iommu_domain_ops) {
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 3b8013afcec0de..3fabe187ea7815 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -244,6 +244,7 @@ static inline u32 arm_smmu_strtab_l2_idx(u32 sid)
#define STRTAB_STE_0_CFG_BYPASS 4
#define STRTAB_STE_0_CFG_S1_TRANS 5
#define STRTAB_STE_0_CFG_S2_TRANS 6
+#define STRTAB_STE_0_CFG_NESTED 7

#define STRTAB_STE_0_S1FMT GENMASK_ULL(5, 4)
#define STRTAB_STE_0_S1FMT_LINEAR 0
@@ -295,6 +296,15 @@ static inline u32 arm_smmu_strtab_l2_idx(u32 sid)

#define STRTAB_STE_3_S2TTB_MASK GENMASK_ULL(51, 4)

+/* These bits can be controlled by userspace for STRTAB_STE_0_CFG_NESTED */
+#define STRTAB_STE_0_NESTING_ALLOWED \
+ cpu_to_le64(STRTAB_STE_0_V | STRTAB_STE_0_CFG | STRTAB_STE_0_S1FMT | \
+ STRTAB_STE_0_S1CTXPTR_MASK | STRTAB_STE_0_S1CDMAX)
+#define STRTAB_STE_1_NESTING_ALLOWED \
+ cpu_to_le64(STRTAB_STE_1_S1DSS | STRTAB_STE_1_S1CIR | \
+ STRTAB_STE_1_S1COR | STRTAB_STE_1_S1CSH | \
+ STRTAB_STE_1_S1STALLD)
+
/*
* Context descriptors.
*
@@ -514,6 +524,7 @@ struct arm_smmu_cmdq_ent {
};
} cfgi;

+ #define CMDQ_OP_TLBI_NH_ALL 0x10
#define CMDQ_OP_TLBI_NH_ASID 0x11
#define CMDQ_OP_TLBI_NH_VA 0x12
#define CMDQ_OP_TLBI_EL2_ALL 0x20
@@ -815,10 +826,18 @@ struct arm_smmu_domain {
struct list_head devices;
spinlock_t devices_lock;
bool enforce_cache_coherency : 1;
+ bool nest_parent : 1;

struct mmu_notifier mmu_notifier;
};

+struct arm_smmu_nested_domain {
+ struct iommu_domain domain;
+ struct arm_vsmmu *vsmmu;
+
+ __le64 ste[2];
+};
+
/* The following are exposed for testing purposes. */
struct arm_smmu_entry_writer_ops;
struct arm_smmu_entry_writer {
@@ -863,6 +882,12 @@ static inline struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
return container_of(dom, struct arm_smmu_domain, domain);
}

+static inline struct arm_smmu_nested_domain *
+to_smmu_nested_domain(struct iommu_domain *dom)
+{
+ return container_of(dom, struct arm_smmu_nested_domain, domain);
+}
+
extern struct xarray arm_smmu_asid_xa;
extern struct mutex arm_smmu_asid_lock;

@@ -909,6 +934,7 @@ struct arm_smmu_attach_state {
struct iommu_domain *old_domain;
struct arm_smmu_master *master;
bool cd_needs_ats;
+ bool disable_ats;
ioasid_t ssid;
/* Resulting state */
bool ats_enabled;
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 27c5117db985b2..47ee35ce050b63 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -396,6 +396,26 @@ struct iommu_hwpt_vtd_s1 {
__u32 __reserved;
};

+/**
+ * struct iommu_hwpt_arm_smmuv3 - ARM SMMUv3 nested STE
+ * (IOMMU_HWPT_DATA_ARM_SMMUV3)
+ *
+ * @ste: The first two double words of the user space Stream Table Entry for
+ * the translation. Must be little-endian.
+ * Allowed fields: (Refer to "5.2 Stream Table Entry" in SMMUv3 HW Spec)
+ * - word-0: V, Cfg, S1Fmt, S1ContextPtr, S1CDMax
+ * - word-1: S1DSS, S1CIR, S1COR, S1CSH, S1STALLD
+ *
+ * -EIO will be returned if @ste is not legal or contains any non-allowed field.
+ * Cfg can be used to select a S1, Bypass or Abort configuration. A Bypass
+ * nested domain will translate the same as the nesting parent. The S1 will
+ * install a Context Descriptor Table pointing at userspace memory translated
+ * by the nesting parent.
+ */
+struct iommu_hwpt_arm_smmuv3 {
+ __aligned_le64 ste[2];
+};
+
/**
* enum iommu_hwpt_data_type - IOMMU HWPT Data Type
* @IOMMU_HWPT_DATA_NONE: no data
--
2.43.0