[PATCH v4 0/2] iommu/arm-smmu-v3: Two vsmmu impl_ops cleanups

[PATCH v4 0/2] iommu/arm-smmu-v3: Two vsmmu impl_ops cleanups

[Nicolin Chen]

Since the vsmmu and cmdqv patches were accepeted via the iommufd tree,
this is based on Jason's for-next tree.

Per request from Will following the accepted latest vcmdq series to clean
up the impl_ops:

https://lore.kernel.org/linux-iommu/aHE4Y-fbucm-j-yi@willie-the-truck/
"
 It would be nice to avoid adding data members to the ops structure, if
 at all possible. The easiest thing would probably be to add a function
 for getting the vsmmu size and then pushing the two checks against
 'vsmmu_type' down into the impl_ops callbacks so that: 

   1. If the type is IOMMU_VIOMMU_TYPE_ARM_SMMUV3, we don't bother with
      the impl_ops at all in arm_vsmmu_init() and arm_smmu_get_viommu_size()
 
   2. Otherwise, we pass the type into the impl_ops and they can check it

 Of course, that can be a patch on top of the series as there's no point
 respinning the whole just for this.
"

Add two clean up patches with the first one doing 1 and 2 to prioritize
IOMMU_VIOMMU_TYPE_ARM_SMMUV3 always, and the second one dropping static
vsmmu_type and vsmmu_size data members.

Changelog
v4:
 * Add Reviewed-by from Pranjal
 * Update inline comments
v3:
 https://lore.kernel.org/all/20250721200444.1740461-1-nicolinc@nvidia.com/
 * Add Acked-by from Will
 * Use logical "!=" instead of arithmetic "^"
v2:
 https://lore.kernel.org/all/20250721191236.1739951-1-nicolinc@nvidia.com/
 * Add Acked-by from Will
 * Move get_viommu_size and vsmmu_init validation to arm_smmu_impl_probe()
v1:
 https://lore.kernel.org/all/20250718234822.1734190-1-nicolinc@nvidia.com/

Nicolin Chen (2):
  iommu/arm-smmu-v3: Do not bother impl_ops if
    IOMMU_VIOMMU_TYPE_ARM_SMMUV3
  iommu/arm-smmu-v3: Replace vsmmu_size/type with get_viommu_size

 .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 20 +++++++++----------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 14 +++++++++++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  3 +--
 .../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c    | 17 ++++++++++++++--
 4 files changed, 39 insertions(+), 15 deletions(-)


base-commit: ab6bc44159d8f0c4ee757e0ce041fa9033e0ead8
-- 
2.43.0

[PATCH v4 1/2] iommu/arm-smmu-v3: Do not bother impl_ops if IOMMU_VIOMMU_TYPE_ARM_SMMUV3

[Nicolin Chen]

When viommu type is IOMMU_VIOMMU_TYPE_ARM_SMMUV3, always return or init the
standard struct arm_vsmmu, instead of going through impl_ops that must have
its own viommu type than the standard IOMMU_VIOMMU_TYPE_ARM_SMMUV3.

Given that arm_vsmmu_init() is called after arm_smmu_get_viommu_size(), any
unsupported viommu->type must be a corruption. And it must be a driver bug
that its vsmmu_size and vsmmu_init ops aren't paired. Warn these two cases.

Suggested-by: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 27 +++++++++++--------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 14 ++++++++++
 2 files changed, 30 insertions(+), 11 deletions(-)

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 d9bea8f1f636d..b963b9b3de542 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
@@ -420,14 +420,13 @@ size_t arm_smmu_get_viommu_size(struct device *dev,
 	    !(smmu->features & ARM_SMMU_FEAT_S2FWB))
 		return 0;
 
-	if (smmu->impl_ops && smmu->impl_ops->vsmmu_size &&
-	    viommu_type == smmu->impl_ops->vsmmu_type)
-		return smmu->impl_ops->vsmmu_size;
+	if (viommu_type == IOMMU_VIOMMU_TYPE_ARM_SMMUV3)
+		return VIOMMU_STRUCT_SIZE(struct arm_vsmmu, core);
 
-	if (viommu_type != IOMMU_VIOMMU_TYPE_ARM_SMMUV3)
+	if (!smmu->impl_ops || !smmu->impl_ops->vsmmu_size ||
+	    viommu_type != smmu->impl_ops->vsmmu_type)
 		return 0;
-
-	return VIOMMU_STRUCT_SIZE(struct arm_vsmmu, core);
+	return smmu->impl_ops->vsmmu_size;
 }
 
 int arm_vsmmu_init(struct iommufd_viommu *viommu,
@@ -447,12 +446,18 @@ int arm_vsmmu_init(struct iommufd_viommu *viommu,
 	/* FIXME Move VMID allocation from the S2 domain allocation to here */
 	vsmmu->vmid = s2_parent->s2_cfg.vmid;
 
-	if (smmu->impl_ops && smmu->impl_ops->vsmmu_init &&
-	    viommu->type == smmu->impl_ops->vsmmu_type)
-		return smmu->impl_ops->vsmmu_init(vsmmu, user_data);
+	if (viommu->type == IOMMU_VIOMMU_TYPE_ARM_SMMUV3) {
+		viommu->ops = &arm_vsmmu_ops;
+		return 0;
+	}
 
-	viommu->ops = &arm_vsmmu_ops;
-	return 0;
+	/*
+	 * Unsupported type should be rejected by arm_smmu_get_viommu_size.
+	 * Seeing one here indicates a kernel bug or some data corruption.
+	 */
+	if (WARN_ON(viommu->type != smmu->impl_ops->vsmmu_type))
+		return -EOPNOTSUPP;
+	return smmu->impl_ops->vsmmu_init(vsmmu, user_data);
 }
 
 int arm_vmaster_report_event(struct arm_smmu_vmaster *vmaster, u64 *evt)
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 181d07bc1a9d4..9f4ad37058010 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4703,6 +4703,7 @@ static void arm_smmu_impl_remove(void *data)
 static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
 {
 	struct arm_smmu_device *new_smmu = ERR_PTR(-ENODEV);
+	const struct arm_smmu_impl_ops *ops;
 	int ret;
 
 	if (smmu->impl_dev && (smmu->options & ARM_SMMU_OPT_TEGRA241_CMDQV))
@@ -4713,11 +4714,24 @@ static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
 	if (IS_ERR(new_smmu))
 		return new_smmu;
 
+	ops = new_smmu->impl_ops;
+	if (ops) {
+		/* vsmmu_size and vsmmu_init ops must be paired */
+		if (WARN_ON(!ops->vsmmu_size != !ops->vsmmu_init)) {
+			ret = -EINVAL;
+			goto err_remove;
+		}
+	}
+
 	ret = devm_add_action_or_reset(new_smmu->dev, arm_smmu_impl_remove,
 				       new_smmu);
 	if (ret)
 		return ERR_PTR(ret);
 	return new_smmu;
+
+err_remove:
+	arm_smmu_impl_remove(new_smmu);
+	return ERR_PTR(ret);
 }
 
 static int arm_smmu_device_probe(struct platform_device *pdev)
-- 
2.43.0

[PATCH v4 2/2] iommu/arm-smmu-v3: Replace vsmmu_size/type with get_viommu_size

[Nicolin Chen]

It's more flexible to have a get_viommu_size op. Replace static vsmmu_size
and vsmmu_type with that.

Suggested-by: Will Deacon <will@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 11 ++---------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c     |  4 ++--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h     |  3 +--
 drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c  | 17 +++++++++++++++--
 4 files changed, 20 insertions(+), 15 deletions(-)

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 b963b9b3de542..8cd8929bbfdf8 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
@@ -423,10 +423,9 @@ size_t arm_smmu_get_viommu_size(struct device *dev,
 	if (viommu_type == IOMMU_VIOMMU_TYPE_ARM_SMMUV3)
 		return VIOMMU_STRUCT_SIZE(struct arm_vsmmu, core);
 
-	if (!smmu->impl_ops || !smmu->impl_ops->vsmmu_size ||
-	    viommu_type != smmu->impl_ops->vsmmu_type)
+	if (!smmu->impl_ops || !smmu->impl_ops->get_viommu_size)
 		return 0;
-	return smmu->impl_ops->vsmmu_size;
+	return smmu->impl_ops->get_viommu_size(viommu_type);
 }
 
 int arm_vsmmu_init(struct iommufd_viommu *viommu,
@@ -451,12 +450,6 @@ int arm_vsmmu_init(struct iommufd_viommu *viommu,
 		return 0;
 	}
 
-	/*
-	 * Unsupported type should be rejected by arm_smmu_get_viommu_size.
-	 * Seeing one here indicates a kernel bug or some data corruption.
-	 */
-	if (WARN_ON(viommu->type != smmu->impl_ops->vsmmu_type))
-		return -EOPNOTSUPP;
 	return smmu->impl_ops->vsmmu_init(vsmmu, user_data);
 }
 
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 9f4ad37058010..f56113107c8ad 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4716,8 +4716,8 @@ static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
 
 	ops = new_smmu->impl_ops;
 	if (ops) {
-		/* vsmmu_size and vsmmu_init ops must be paired */
-		if (WARN_ON(!ops->vsmmu_size != !ops->vsmmu_init)) {
+		/* get_viommu_size and vsmmu_init ops must be paired */
+		if (WARN_ON(!ops->get_viommu_size != !ops->vsmmu_init)) {
 			ret = -EINVAL;
 			goto err_remove;
 		}
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 3fa02c51df9f3..e332f5ba2f8a2 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -728,8 +728,7 @@ struct arm_smmu_impl_ops {
 	 */
 	void *(*hw_info)(struct arm_smmu_device *smmu, u32 *length,
 			 enum iommu_hw_info_type *type);
-	const size_t vsmmu_size;
-	const enum iommu_viommu_type vsmmu_type;
+	size_t (*get_viommu_size)(enum iommu_viommu_type viommu_type);
 	int (*vsmmu_init)(struct arm_vsmmu *vsmmu,
 			  const struct iommu_user_data *user_data);
 };
diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index 4c86eacd36b16..be1aaaf8cd17c 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -832,6 +832,13 @@ static void *tegra241_cmdqv_hw_info(struct arm_smmu_device *smmu, u32 *length,
 	return info;
 }
 
+static size_t tegra241_cmdqv_get_vintf_size(enum iommu_viommu_type viommu_type)
+{
+	if (viommu_type != IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV)
+		return 0;
+	return VIOMMU_STRUCT_SIZE(struct tegra241_vintf, vsmmu.core);
+}
+
 static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = {
 	/* For in-kernel use */
 	.get_secondary_cmdq = tegra241_cmdqv_get_cmdq,
@@ -839,8 +846,7 @@ static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = {
 	.device_remove = tegra241_cmdqv_remove,
 	/* For user-space use */
 	.hw_info = tegra241_cmdqv_hw_info,
-	.vsmmu_size = VIOMMU_STRUCT_SIZE(struct tegra241_vintf, vsmmu.core),
-	.vsmmu_type = IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV,
+	.get_viommu_size = tegra241_cmdqv_get_vintf_size,
 	.vsmmu_init = tegra241_cmdqv_init_vintf_user,
 };
 
@@ -1273,6 +1279,13 @@ tegra241_cmdqv_init_vintf_user(struct arm_vsmmu *vsmmu,
 	phys_addr_t page0_base;
 	int ret;
 
+	/*
+	 * Unsupported type should be rejected by tegra241_cmdqv_get_vintf_size.
+	 * Seeing one here indicates a kernel bug or some data corruption.
+	 */
+	if (WARN_ON(vsmmu->core.type != IOMMU_VIOMMU_TYPE_TEGRA241_CMDQV))
+		return -EOPNOTSUPP;
+
 	if (!user_data)
 		return -EINVAL;
 
-- 
2.43.0

Re: [PATCH v4 0/2] iommu/arm-smmu-v3: Two vsmmu impl_ops cleanups

[Jason Gunthorpe]

On Thu, Jul 24, 2025 at 03:10:00PM -0700, Nicolin Chen wrote:
> Nicolin Chen (2):
>   iommu/arm-smmu-v3: Do not bother impl_ops if
>     IOMMU_VIOMMU_TYPE_ARM_SMMUV3
>   iommu/arm-smmu-v3: Replace vsmmu_size/type with get_viommu_size
> 
>  .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c     | 20 +++++++++----------
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 14 +++++++++++++
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  3 +--
>  .../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c    | 17 ++++++++++++++--
>  4 files changed, 39 insertions(+), 15 deletions(-)

Applied, thanks

Jason