[PATCH v13 00/10] iommu: I/O page faults for SMMUv3

[PATCH v13 00/10] iommu: I/O page faults for SMMUv3

[Jean-Philippe Brucker]

Add stall support to the SMMUv3 driver, along with a common I/O Page
Fault handler.

Since v12 [1]:
* Fixed failure path of arm_smmu_insert_master(), in patch 07 (Keqian
  Zhu)
* In arm_smmu_handle_evt(), patch 10, don't report IPA field on stage-1
  faults, and report accurate fault reason (Eric Auger)
* Fix possible use-after-free in arm_smmu_handle_evt(), patch 10: if a
  master is removed while we handle its events, we could in theory
  dereference a freed master struct. Hold streams_mutex while using a
  master struct obtained with arm_smmu_find_master().


Future work regarding IOPF:
* Keep stall disabled by default, only enable it per CD when drivers
  request it [2][3].
* Add PRI support to SMMUv3.
* Route all recoverable faults through io-pgfault.c, so we can track
  partial faults better [4].
* Nested IOPF [5].

[1] https://lore.kernel.org/linux-iommu/20210127154322.3959196-1-jean-philippe@linaro.org/
[2] https://lore.kernel.org/linux-iommu/22fa4120-eadf-20d5-0d0a-9935aa0f1fb5@hisilicon.com/
[3] https://lore.kernel.org/linux-iommu/YAhui7UOw7743shI@myrica/
[4] https://lore.kernel.org/kvm/YB0f5Yno9frihQq4@myrica/
[5] https://lore.kernel.org/linux-acpi/MWHPR11MB188653AF6EFA0E55DE17815F8CA40@MWHPR11MB1886.namprd11.prod.outlook.com/

Jean-Philippe Brucker (10):
  iommu: Fix comment for struct iommu_fwspec
  iommu/arm-smmu-v3: Use device properties for pasid-num-bits
  iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA
  iommu/vt-d: Support IOMMU_DEV_FEAT_IOPF
  uacce: Enable IOMMU_DEV_FEAT_IOPF
  iommu: Add a page fault handler
  iommu/arm-smmu-v3: Maintain a SID->device structure
  dt-bindings: document stall property for IOMMU masters
  ACPI/IORT: Enable stall support for platform devices
  iommu/arm-smmu-v3: Add stall support for platform devices

 drivers/iommu/Makefile                        |   1 +
 .../devicetree/bindings/iommu/iommu.txt       |  18 +
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  56 ++-
 drivers/iommu/iommu-sva-lib.h                 |  53 ++
 include/linux/iommu.h                         |  26 +-
 drivers/acpi/arm64/iort.c                     |  15 +-
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  59 ++-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 354 ++++++++++++--
 drivers/iommu/intel/iommu.c                   |  11 +-
 drivers/iommu/io-pgfault.c                    | 461 ++++++++++++++++++
 drivers/iommu/of_iommu.c                      |   5 -
 drivers/misc/uacce/uacce.c                    |  39 +-
 12 files changed, 1024 insertions(+), 74 deletions(-)
 create mode 100644 drivers/iommu/io-pgfault.c

-- 
2.30.1

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[PATCH v13 01/10] iommu: Fix comment for struct iommu_fwspec

[Jean-Philippe Brucker]

Commit 986d5ecc5699 ("iommu: Move fwspec->iommu_priv to struct
dev_iommu") removed iommu_priv from fwspec and commit 5702ee24182f
("ACPI/IORT: Check ATS capability in root complex nodes") added @flags.
Update the struct doc.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 include/linux/iommu.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e7fe519430a..1d422bf722a1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -571,7 +571,7 @@ struct iommu_group *fsl_mc_device_group(struct device *dev);
  * struct iommu_fwspec - per-device IOMMU instance data
  * @ops: ops for this device's IOMMU
  * @iommu_fwnode: firmware handle for this device's IOMMU
- * @iommu_priv: IOMMU driver private data for this device
+ * @flags: IOMMU_FWSPEC_* flags
  * @num_pasid_bits: number of PASID bits supported by this device
  * @num_ids: number of associated device IDs
  * @ids: IDs which this device may present to the IOMMU
-- 
2.30.1

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Re: [PATCH v13 01/10] iommu: Fix comment for struct iommu_fwspec

[Will Deacon]

On Tue, Mar 02, 2021 at 10:26:37AM +0100, Jean-Philippe Brucker wrote:
> Commit 986d5ecc5699 ("iommu: Move fwspec->iommu_priv to struct
> dev_iommu") removed iommu_priv from fwspec and commit 5702ee24182f
> ("ACPI/IORT: Check ATS capability in root complex nodes") added @flags.
> Update the struct doc.
> 
> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  include/linux/iommu.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Will Deacon <will@kernel.org>

Will
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[PATCH v13 02/10] iommu/arm-smmu-v3: Use device properties for pasid-num-bits

[Jean-Philippe Brucker]

The pasid-num-bits property shouldn't need a dedicated fwspec field,
it's a job for device properties. Add properties for IORT, and access
the number of PASID bits using device_property_read_u32().

Suggested-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 include/linux/iommu.h                       |  2 --
 drivers/acpi/arm64/iort.c                   | 13 +++++++------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  3 ++-
 drivers/iommu/of_iommu.c                    |  5 -----
 4 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 1d422bf722a1..16ce75693d83 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -572,7 +572,6 @@ struct iommu_group *fsl_mc_device_group(struct device *dev);
  * @ops: ops for this device's IOMMU
  * @iommu_fwnode: firmware handle for this device's IOMMU
  * @flags: IOMMU_FWSPEC_* flags
- * @num_pasid_bits: number of PASID bits supported by this device
  * @num_ids: number of associated device IDs
  * @ids: IDs which this device may present to the IOMMU
  */
@@ -580,7 +579,6 @@ struct iommu_fwspec {
 	const struct iommu_ops	*ops;
 	struct fwnode_handle	*iommu_fwnode;
 	u32			flags;
-	u32			num_pasid_bits;
 	unsigned int		num_ids;
 	u32			ids[];
 };
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 2494138a6905..3912a1f6058e 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -968,15 +968,16 @@ static int iort_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 static void iort_named_component_init(struct device *dev,
 				      struct acpi_iort_node *node)
 {
+	struct property_entry props[2] = {};
 	struct acpi_iort_named_component *nc;
-	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
-
-	if (!fwspec)
-		return;
 
 	nc = (struct acpi_iort_named_component *)node->node_data;
-	fwspec->num_pasid_bits = FIELD_GET(ACPI_IORT_NC_PASID_BITS,
-					   nc->node_flags);
+	props[0] = PROPERTY_ENTRY_U32("pasid-num-bits",
+				      FIELD_GET(ACPI_IORT_NC_PASID_BITS,
+						nc->node_flags));
+
+	if (device_add_properties(dev, props))
+		dev_warn(dev, "Could not add device properties\n");
 }
 
 static int iort_nc_iommu_map(struct device *dev, struct acpi_iort_node *node)
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 8594b4a83043..7edce914c45e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2392,7 +2392,8 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 		}
 	}
 
-	master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
+	device_property_read_u32(dev, "pasid-num-bits", &master->ssid_bits);
+	master->ssid_bits = min(smmu->ssid_bits, master->ssid_bits);
 
 	/*
 	 * Note that PASID must be enabled before, and disabled after ATS:
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index e505b9130a1c..a9d2df001149 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -210,11 +210,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 					     of_pci_iommu_init, &info);
 	} else {
 		err = of_iommu_configure_device(master_np, dev, id);
-
-		fwspec = dev_iommu_fwspec_get(dev);
-		if (!err && fwspec)
-			of_property_read_u32(master_np, "pasid-num-bits",
-					     &fwspec->num_pasid_bits);
 	}
 
 	/*
-- 
2.30.1

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Re: [PATCH v13 02/10] iommu/arm-smmu-v3: Use device properties for pasid-num-bits

[Will Deacon]

On Tue, Mar 02, 2021 at 10:26:38AM +0100, Jean-Philippe Brucker wrote:
> The pasid-num-bits property shouldn't need a dedicated fwspec field,
> it's a job for device properties. Add properties for IORT, and access
> the number of PASID bits using device_property_read_u32().
> 
> Suggested-by: Robin Murphy <robin.murphy@arm.com>
> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  include/linux/iommu.h                       |  2 --
>  drivers/acpi/arm64/iort.c                   | 13 +++++++------
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  3 ++-
>  drivers/iommu/of_iommu.c                    |  5 -----
>  4 files changed, 9 insertions(+), 14 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Will
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[PATCH v13 03/10] iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA

[Jean-Philippe Brucker]

Some devices manage I/O Page Faults (IOPF) themselves instead of relying
on PCIe PRI or Arm SMMU stall. Allow their drivers to enable SVA without
mandating IOMMU-managed IOPF. The other device drivers now need to first
enable IOMMU_DEV_FEAT_IOPF before enabling IOMMU_DEV_FEAT_SVA. Enabling
IOMMU_DEV_FEAT_IOPF on its own doesn't have any effect visible to the
device driver, it is used in combination with other features.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Zhou Wang <wangzhou1@hisilicon.com>
---
 include/linux/iommu.h | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 16ce75693d83..45c4eb372f56 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -156,10 +156,24 @@ struct iommu_resv_region {
 	enum iommu_resv_type	type;
 };
 
-/* Per device IOMMU features */
+/**
+ * enum iommu_dev_features - Per device IOMMU features
+ * @IOMMU_DEV_FEAT_AUX: Auxiliary domain feature
+ * @IOMMU_DEV_FEAT_SVA: Shared Virtual Addresses
+ * @IOMMU_DEV_FEAT_IOPF: I/O Page Faults such as PRI or Stall. Generally
+ *			 enabling %IOMMU_DEV_FEAT_SVA requires
+ *			 %IOMMU_DEV_FEAT_IOPF, but some devices manage I/O Page
+ *			 Faults themselves instead of relying on the IOMMU. When
+ *			 supported, this feature must be enabled before and
+ *			 disabled after %IOMMU_DEV_FEAT_SVA.
+ *
+ * Device drivers query whether a feature is supported using
+ * iommu_dev_has_feature(), and enable it using iommu_dev_enable_feature().
+ */
 enum iommu_dev_features {
-	IOMMU_DEV_FEAT_AUX,	/* Aux-domain feature */
-	IOMMU_DEV_FEAT_SVA,	/* Shared Virtual Addresses */
+	IOMMU_DEV_FEAT_AUX,
+	IOMMU_DEV_FEAT_SVA,
+	IOMMU_DEV_FEAT_IOPF,
 };
 
 #define IOMMU_PASID_INVALID	(-1U)
-- 
2.30.1

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Re: [PATCH v13 03/10] iommu: Separate IOMMU_DEV_FEAT_IOPF from IOMMU_DEV_FEAT_SVA

[Lu Baolu]

On 3/2/21 5:26 PM, Jean-Philippe Brucker wrote:
> Some devices manage I/O Page Faults (IOPF) themselves instead of relying
> on PCIe PRI or Arm SMMU stall. Allow their drivers to enable SVA without
> mandating IOMMU-managed IOPF. The other device drivers now need to first
> enable IOMMU_DEV_FEAT_IOPF before enabling IOMMU_DEV_FEAT_SVA. Enabling
> IOMMU_DEV_FEAT_IOPF on its own doesn't have any effect visible to the
> device driver, it is used in combination with other features.
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
> Cc: Zhou Wang <wangzhou1@hisilicon.com>
> ---
>   include/linux/iommu.h | 20 +++++++++++++++++---
>   1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 16ce75693d83..45c4eb372f56 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -156,10 +156,24 @@ struct iommu_resv_region {
>   	enum iommu_resv_type	type;
>   };
>   
> -/* Per device IOMMU features */
> +/**
> + * enum iommu_dev_features - Per device IOMMU features
> + * @IOMMU_DEV_FEAT_AUX: Auxiliary domain feature
> + * @IOMMU_DEV_FEAT_SVA: Shared Virtual Addresses
> + * @IOMMU_DEV_FEAT_IOPF: I/O Page Faults such as PRI or Stall. Generally
> + *			 enabling %IOMMU_DEV_FEAT_SVA requires
> + *			 %IOMMU_DEV_FEAT_IOPF, but some devices manage I/O Page
> + *			 Faults themselves instead of relying on the IOMMU. When
> + *			 supported, this feature must be enabled before and
> + *			 disabled after %IOMMU_DEV_FEAT_SVA.
> + *
> + * Device drivers query whether a feature is supported using
> + * iommu_dev_has_feature(), and enable it using iommu_dev_enable_feature().
> + */
>   enum iommu_dev_features {
> -	IOMMU_DEV_FEAT_AUX,	/* Aux-domain feature */
> -	IOMMU_DEV_FEAT_SVA,	/* Shared Virtual Addresses */
> +	IOMMU_DEV_FEAT_AUX,
> +	IOMMU_DEV_FEAT_SVA,
> +	IOMMU_DEV_FEAT_IOPF,
>   };
>   
>   #define IOMMU_PASID_INVALID	(-1U)
> 

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu
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[PATCH v13 04/10] iommu/vt-d: Support IOMMU_DEV_FEAT_IOPF

[Jean-Philippe Brucker]

Allow drivers to query and enable IOMMU_DEV_FEAT_IOPF, which amounts to
checking whether PRI is enabled.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ee0932307d64..c5c5fd444779 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5343,6 +5343,8 @@ static int siov_find_pci_dvsec(struct pci_dev *pdev)
 static bool
 intel_iommu_dev_has_feat(struct device *dev, enum iommu_dev_features feat)
 {
+	struct device_domain_info *info = get_domain_info(dev);
+
 	if (feat == IOMMU_DEV_FEAT_AUX) {
 		int ret;
 
@@ -5357,13 +5359,13 @@ intel_iommu_dev_has_feat(struct device *dev, enum iommu_dev_features feat)
 		return !!siov_find_pci_dvsec(to_pci_dev(dev));
 	}
 
-	if (feat == IOMMU_DEV_FEAT_SVA) {
-		struct device_domain_info *info = get_domain_info(dev);
+	if (feat == IOMMU_DEV_FEAT_IOPF)
+		return info && info->pri_supported;
 
+	if (feat == IOMMU_DEV_FEAT_SVA)
 		return info && (info->iommu->flags & VTD_FLAG_SVM_CAPABLE) &&
 			info->pasid_supported && info->pri_supported &&
 			info->ats_supported;
-	}
 
 	return false;
 }
@@ -5374,6 +5376,9 @@ intel_iommu_dev_enable_feat(struct device *dev, enum iommu_dev_features feat)
 	if (feat == IOMMU_DEV_FEAT_AUX)
 		return intel_iommu_enable_auxd(dev);
 
+	if (feat == IOMMU_DEV_FEAT_IOPF)
+		return intel_iommu_dev_has_feat(dev, feat) ? 0 : -ENODEV;
+
 	if (feat == IOMMU_DEV_FEAT_SVA) {
 		struct device_domain_info *info = get_domain_info(dev);
 
-- 
2.30.1

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[PATCH v13 05/10] uacce: Enable IOMMU_DEV_FEAT_IOPF

[Jean-Philippe Brucker]

The IOPF (I/O Page Fault) feature is now enabled independently from the
SVA feature, because some IOPF implementations are device-specific and
do not require IOMMU support for PCIe PRI or Arm SMMU stall.

Enable IOPF unconditionally when enabling SVA for now. In the future, if
a device driver implementing a uacce interface doesn't need IOPF
support, it will need to tell the uacce module, for example with a new
flag.

Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Zhou Wang <wangzhou1@hisilicon.com>
---
 drivers/misc/uacce/uacce.c | 39 +++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index d07af4edfcac..6db7a98486ec 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -385,6 +385,33 @@ static void uacce_release(struct device *dev)
 	kfree(uacce);
 }
 
+static unsigned int uacce_enable_sva(struct device *parent, unsigned int flags)
+{
+	if (!(flags & UACCE_DEV_SVA))
+		return flags;
+
+	flags &= ~UACCE_DEV_SVA;
+
+	if (iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_IOPF))
+		return flags;
+
+	if (iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_SVA)) {
+		iommu_dev_disable_feature(parent, IOMMU_DEV_FEAT_IOPF);
+		return flags;
+	}
+
+	return flags | UACCE_DEV_SVA;
+}
+
+static void uacce_disable_sva(struct uacce_device *uacce)
+{
+	if (!(uacce->flags & UACCE_DEV_SVA))
+		return;
+
+	iommu_dev_disable_feature(uacce->parent, IOMMU_DEV_FEAT_SVA);
+	iommu_dev_disable_feature(uacce->parent, IOMMU_DEV_FEAT_IOPF);
+}
+
 /**
  * uacce_alloc() - alloc an accelerator
  * @parent: pointer of uacce parent device
@@ -404,11 +431,7 @@ struct uacce_device *uacce_alloc(struct device *parent,
 	if (!uacce)
 		return ERR_PTR(-ENOMEM);
 
-	if (flags & UACCE_DEV_SVA) {
-		ret = iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_SVA);
-		if (ret)
-			flags &= ~UACCE_DEV_SVA;
-	}
+	flags = uacce_enable_sva(parent, flags);
 
 	uacce->parent = parent;
 	uacce->flags = flags;
@@ -432,8 +455,7 @@ struct uacce_device *uacce_alloc(struct device *parent,
 	return uacce;
 
 err_with_uacce:
-	if (flags & UACCE_DEV_SVA)
-		iommu_dev_disable_feature(uacce->parent, IOMMU_DEV_FEAT_SVA);
+	uacce_disable_sva(uacce);
 	kfree(uacce);
 	return ERR_PTR(ret);
 }
@@ -487,8 +509,7 @@ void uacce_remove(struct uacce_device *uacce)
 	mutex_unlock(&uacce->queues_lock);
 
 	/* disable sva now since no opened queues */
-	if (uacce->flags & UACCE_DEV_SVA)
-		iommu_dev_disable_feature(uacce->parent, IOMMU_DEV_FEAT_SVA);
+	uacce_disable_sva(uacce);
 
 	if (uacce->cdev)
 		cdev_device_del(uacce->cdev, &uacce->dev);
-- 
2.30.1

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iommu@lists.linux-foundation.org
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[PATCH v13 06/10] iommu: Add a page fault handler

[Jean-Philippe Brucker]

Some systems allow devices to handle I/O Page Faults in the core mm. For
example systems implementing the PCIe PRI extension or Arm SMMU stall
model. Infrastructure for reporting these recoverable page faults was
added to the IOMMU core by commit 0c830e6b3282 ("iommu: Introduce device
fault report API"). Add a page fault handler for host SVA.

IOMMU driver can now instantiate several fault workqueues and link them
to IOPF-capable devices. Drivers can choose between a single global
workqueue, one per IOMMU device, one per low-level fault queue, one per
domain, etc.

When it receives a fault event, most commonly in an IRQ handler, the
IOMMU driver reports the fault using iommu_report_device_fault(), which
calls the registered handler. The page fault handler then calls the mm
fault handler, and reports either success or failure with
iommu_page_response(). After the handler succeeds, the hardware retries
the access.

The iopf_param pointer could be embedded into iommu_fault_param. But
putting iopf_param into the iommu_param structure allows us not to care
about ordering between calls to iopf_queue_add_device() and
iommu_register_device_fault_handler().

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/Makefile        |   1 +
 drivers/iommu/iommu-sva-lib.h |  53 ++++
 include/linux/iommu.h         |   2 +
 drivers/iommu/io-pgfault.c    | 461 ++++++++++++++++++++++++++++++++++
 4 files changed, 517 insertions(+)
 create mode 100644 drivers/iommu/io-pgfault.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 61bd30cd8369..60fafc23dee6 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -28,3 +28,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
 obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
 obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
 obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o
+obj-$(CONFIG_IOMMU_SVA_LIB) += io-pgfault.o
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index b40990aef3fd..031155010ca8 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -12,4 +12,57 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
 void iommu_sva_free_pasid(struct mm_struct *mm);
 struct mm_struct *iommu_sva_find(ioasid_t pasid);
 
+/* I/O Page fault */
+struct device;
+struct iommu_fault;
+struct iopf_queue;
+
+#ifdef CONFIG_IOMMU_SVA_LIB
+int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
+
+int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev);
+int iopf_queue_remove_device(struct iopf_queue *queue,
+			     struct device *dev);
+int iopf_queue_flush_dev(struct device *dev);
+struct iopf_queue *iopf_queue_alloc(const char *name);
+void iopf_queue_free(struct iopf_queue *queue);
+int iopf_queue_discard_partial(struct iopf_queue *queue);
+
+#else /* CONFIG_IOMMU_SVA_LIB */
+static inline int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
+{
+	return -ENODEV;
+}
+
+static inline int iopf_queue_add_device(struct iopf_queue *queue,
+					struct device *dev)
+{
+	return -ENODEV;
+}
+
+static inline int iopf_queue_remove_device(struct iopf_queue *queue,
+					   struct device *dev)
+{
+	return -ENODEV;
+}
+
+static inline int iopf_queue_flush_dev(struct device *dev)
+{
+	return -ENODEV;
+}
+
+static inline struct iopf_queue *iopf_queue_alloc(const char *name)
+{
+	return NULL;
+}
+
+static inline void iopf_queue_free(struct iopf_queue *queue)
+{
+}
+
+static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_IOMMU_SVA_LIB */
 #endif /* _IOMMU_SVA_LIB_H */
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 45c4eb372f56..86d688c4418f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -367,6 +367,7 @@ struct iommu_fault_param {
  * struct dev_iommu - Collection of per-device IOMMU data
  *
  * @fault_param: IOMMU detected device fault reporting data
+ * @iopf_param:	 I/O Page Fault queue and data
  * @fwspec:	 IOMMU fwspec data
  * @iommu_dev:	 IOMMU device this device is linked to
  * @priv:	 IOMMU Driver private data
@@ -377,6 +378,7 @@ struct iommu_fault_param {
 struct dev_iommu {
 	struct mutex lock;
 	struct iommu_fault_param	*fault_param;
+	struct iopf_device_param	*iopf_param;
 	struct iommu_fwspec		*fwspec;
 	struct iommu_device		*iommu_dev;
 	void				*priv;
diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
new file mode 100644
index 000000000000..1df8c1dcae77
--- /dev/null
+++ b/drivers/iommu/io-pgfault.c
@@ -0,0 +1,461 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Handle device page faults
+ *
+ * Copyright (C) 2020 ARM Ltd.
+ */
+
+#include <linux/iommu.h>
+#include <linux/list.h>
+#include <linux/sched/mm.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#include "iommu-sva-lib.h"
+
+/**
+ * struct iopf_queue - IO Page Fault queue
+ * @wq: the fault workqueue
+ * @devices: devices attached to this queue
+ * @lock: protects the device list
+ */
+struct iopf_queue {
+	struct workqueue_struct		*wq;
+	struct list_head		devices;
+	struct mutex			lock;
+};
+
+/**
+ * struct iopf_device_param - IO Page Fault data attached to a device
+ * @dev: the device that owns this param
+ * @queue: IOPF queue
+ * @queue_list: index into queue->devices
+ * @partial: faults that are part of a Page Request Group for which the last
+ *           request hasn't been submitted yet.
+ */
+struct iopf_device_param {
+	struct device			*dev;
+	struct iopf_queue		*queue;
+	struct list_head		queue_list;
+	struct list_head		partial;
+};
+
+struct iopf_fault {
+	struct iommu_fault		fault;
+	struct list_head		list;
+};
+
+struct iopf_group {
+	struct iopf_fault		last_fault;
+	struct list_head		faults;
+	struct work_struct		work;
+	struct device			*dev;
+};
+
+static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf,
+			       enum iommu_page_response_code status)
+{
+	struct iommu_page_response resp = {
+		.version		= IOMMU_PAGE_RESP_VERSION_1,
+		.pasid			= iopf->fault.prm.pasid,
+		.grpid			= iopf->fault.prm.grpid,
+		.code			= status,
+	};
+
+	if ((iopf->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) &&
+	    (iopf->fault.prm.flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID))
+		resp.flags = IOMMU_PAGE_RESP_PASID_VALID;
+
+	return iommu_page_response(dev, &resp);
+}
+
+static enum iommu_page_response_code
+iopf_handle_single(struct iopf_fault *iopf)
+{
+	vm_fault_t ret;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	unsigned int access_flags = 0;
+	unsigned int fault_flags = FAULT_FLAG_REMOTE;
+	struct iommu_fault_page_request *prm = &iopf->fault.prm;
+	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
+
+	if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
+		return status;
+
+	mm = iommu_sva_find(prm->pasid);
+	if (IS_ERR_OR_NULL(mm))
+		return status;
+
+	mmap_read_lock(mm);
+
+	vma = find_extend_vma(mm, prm->addr);
+	if (!vma)
+		/* Unmapped area */
+		goto out_put_mm;
+
+	if (prm->perm & IOMMU_FAULT_PERM_READ)
+		access_flags |= VM_READ;
+
+	if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
+		access_flags |= VM_WRITE;
+		fault_flags |= FAULT_FLAG_WRITE;
+	}
+
+	if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
+		access_flags |= VM_EXEC;
+		fault_flags |= FAULT_FLAG_INSTRUCTION;
+	}
+
+	if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
+		fault_flags |= FAULT_FLAG_USER;
+
+	if (access_flags & ~vma->vm_flags)
+		/* Access fault */
+		goto out_put_mm;
+
+	ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
+	status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
+		IOMMU_PAGE_RESP_SUCCESS;
+
+out_put_mm:
+	mmap_read_unlock(mm);
+	mmput(mm);
+
+	return status;
+}
+
+static void iopf_handle_group(struct work_struct *work)
+{
+	struct iopf_group *group;
+	struct iopf_fault *iopf, *next;
+	enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
+
+	group = container_of(work, struct iopf_group, work);
+
+	list_for_each_entry_safe(iopf, next, &group->faults, list) {
+		/*
+		 * For the moment, errors are sticky: don't handle subsequent
+		 * faults in the group if there is an error.
+		 */
+		if (status == IOMMU_PAGE_RESP_SUCCESS)
+			status = iopf_handle_single(iopf);
+
+		if (!(iopf->fault.prm.flags &
+		      IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
+			kfree(iopf);
+	}
+
+	iopf_complete_group(group->dev, &group->last_fault, status);
+	kfree(group);
+}
+
+/**
+ * iommu_queue_iopf - IO Page Fault handler
+ * @fault: fault event
+ * @cookie: struct device, passed to iommu_register_device_fault_handler.
+ *
+ * Add a fault to the device workqueue, to be handled by mm.
+ *
+ * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
+ * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
+ * expect a response. It may be generated when disabling a PASID (issuing a
+ * PASID stop request) by some PCI devices.
+ *
+ * The PASID stop request is issued by the device driver before unbind(). Once
+ * it completes, no page request is generated for this PASID anymore and
+ * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 - 6.20.1
+ * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices will wait
+ * for all outstanding page requests to come back with a response before
+ * completing the PASID stop request. Others do not wait for page responses, and
+ * instead issue this Stop Marker that tells us when the PASID can be
+ * reallocated.
+ *
+ * It is safe to discard the Stop Marker because it is an optimization.
+ * a. Page requests, which are posted requests, have been flushed to the IOMMU
+ *    when the stop request completes.
+ * b. The IOMMU driver flushes all fault queues on unbind() before freeing the
+ *    PASID.
+ *
+ * So even though the Stop Marker might be issued by the device *after* the stop
+ * request completes, outstanding faults will have been dealt with by the time
+ * the PASID is freed.
+ *
+ * Return: 0 on success and <0 on error.
+ */
+int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
+{
+	int ret;
+	struct iopf_group *group;
+	struct iopf_fault *iopf, *next;
+	struct iopf_device_param *iopf_param;
+
+	struct device *dev = cookie;
+	struct dev_iommu *param = dev->iommu;
+
+	lockdep_assert_held(&param->lock);
+
+	if (fault->type != IOMMU_FAULT_PAGE_REQ)
+		/* Not a recoverable page fault */
+		return -EOPNOTSUPP;
+
+	/*
+	 * As long as we're holding param->lock, the queue can't be unlinked
+	 * from the device and therefore cannot disappear.
+	 */
+	iopf_param = param->iopf_param;
+	if (!iopf_param)
+		return -ENODEV;
+
+	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
+		iopf = kzalloc(sizeof(*iopf), GFP_KERNEL);
+		if (!iopf)
+			return -ENOMEM;
+
+		iopf->fault = *fault;
+
+		/* Non-last request of a group. Postpone until the last one */
+		list_add(&iopf->list, &iopf_param->partial);
+
+		return 0;
+	}
+
+	group = kzalloc(sizeof(*group), GFP_KERNEL);
+	if (!group) {
+		/*
+		 * The caller will send a response to the hardware. But we do
+		 * need to clean up before leaving, otherwise partial faults
+		 * will be stuck.
+		 */
+		ret = -ENOMEM;
+		goto cleanup_partial;
+	}
+
+	group->dev = dev;
+	group->last_fault.fault = *fault;
+	INIT_LIST_HEAD(&group->faults);
+	list_add(&group->last_fault.list, &group->faults);
+	INIT_WORK(&group->work, iopf_handle_group);
+
+	/* See if we have partial faults for this group */
+	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
+		if (iopf->fault.prm.grpid == fault->prm.grpid)
+			/* Insert *before* the last fault */
+			list_move(&iopf->list, &group->faults);
+	}
+
+	queue_work(iopf_param->queue->wq, &group->work);
+	return 0;
+
+cleanup_partial:
+	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
+		if (iopf->fault.prm.grpid == fault->prm.grpid) {
+			list_del(&iopf->list);
+			kfree(iopf);
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_queue_iopf);
+
+/**
+ * iopf_queue_flush_dev - Ensure that all queued faults have been processed
+ * @dev: the endpoint whose faults need to be flushed.
+ *
+ * The IOMMU driver calls this before releasing a PASID, to ensure that all
+ * pending faults for this PASID have been handled, and won't hit the address
+ * space of the next process that uses this PASID. The driver must make sure
+ * that no new fault is added to the queue. In particular it must flush its
+ * low-level queue before calling this function.
+ *
+ * Return: 0 on success and <0 on error.
+ */
+int iopf_queue_flush_dev(struct device *dev)
+{
+	int ret = 0;
+	struct iopf_device_param *iopf_param;
+	struct dev_iommu *param = dev->iommu;
+
+	if (!param)
+		return -ENODEV;
+
+	mutex_lock(&param->lock);
+	iopf_param = param->iopf_param;
+	if (iopf_param)
+		flush_workqueue(iopf_param->queue->wq);
+	else
+		ret = -ENODEV;
+	mutex_unlock(&param->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iopf_queue_flush_dev);
+
+/**
+ * iopf_queue_discard_partial - Remove all pending partial fault
+ * @queue: the queue whose partial faults need to be discarded
+ *
+ * When the hardware queue overflows, last page faults in a group may have been
+ * lost and the IOMMU driver calls this to discard all partial faults. The
+ * driver shouldn't be adding new faults to this queue concurrently.
+ *
+ * Return: 0 on success and <0 on error.
+ */
+int iopf_queue_discard_partial(struct iopf_queue *queue)
+{
+	struct iopf_fault *iopf, *next;
+	struct iopf_device_param *iopf_param;
+
+	if (!queue)
+		return -EINVAL;
+
+	mutex_lock(&queue->lock);
+	list_for_each_entry(iopf_param, &queue->devices, queue_list) {
+		list_for_each_entry_safe(iopf, next, &iopf_param->partial,
+					 list) {
+			list_del(&iopf->list);
+			kfree(iopf);
+		}
+	}
+	mutex_unlock(&queue->lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iopf_queue_discard_partial);
+
+/**
+ * iopf_queue_add_device - Add producer to the fault queue
+ * @queue: IOPF queue
+ * @dev: device to add
+ *
+ * Return: 0 on success and <0 on error.
+ */
+int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev)
+{
+	int ret = -EBUSY;
+	struct iopf_device_param *iopf_param;
+	struct dev_iommu *param = dev->iommu;
+
+	if (!param)
+		return -ENODEV;
+
+	iopf_param = kzalloc(sizeof(*iopf_param), GFP_KERNEL);
+	if (!iopf_param)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&iopf_param->partial);
+	iopf_param->queue = queue;
+	iopf_param->dev = dev;
+
+	mutex_lock(&queue->lock);
+	mutex_lock(&param->lock);
+	if (!param->iopf_param) {
+		list_add(&iopf_param->queue_list, &queue->devices);
+		param->iopf_param = iopf_param;
+		ret = 0;
+	}
+	mutex_unlock(&param->lock);
+	mutex_unlock(&queue->lock);
+
+	if (ret)
+		kfree(iopf_param);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iopf_queue_add_device);
+
+/**
+ * iopf_queue_remove_device - Remove producer from fault queue
+ * @queue: IOPF queue
+ * @dev: device to remove
+ *
+ * Caller makes sure that no more faults are reported for this device.
+ *
+ * Return: 0 on success and <0 on error.
+ */
+int iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev)
+{
+	int ret = -EINVAL;
+	struct iopf_fault *iopf, *next;
+	struct iopf_device_param *iopf_param;
+	struct dev_iommu *param = dev->iommu;
+
+	if (!param || !queue)
+		return -EINVAL;
+
+	mutex_lock(&queue->lock);
+	mutex_lock(&param->lock);
+	iopf_param = param->iopf_param;
+	if (iopf_param && iopf_param->queue == queue) {
+		list_del(&iopf_param->queue_list);
+		param->iopf_param = NULL;
+		ret = 0;
+	}
+	mutex_unlock(&param->lock);
+	mutex_unlock(&queue->lock);
+	if (ret)
+		return ret;
+
+	/* Just in case some faults are still stuck */
+	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
+		kfree(iopf);
+
+	kfree(iopf_param);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iopf_queue_remove_device);
+
+/**
+ * iopf_queue_alloc - Allocate and initialize a fault queue
+ * @name: a unique string identifying the queue (for workqueue)
+ *
+ * Return: the queue on success and NULL on error.
+ */
+struct iopf_queue *iopf_queue_alloc(const char *name)
+{
+	struct iopf_queue *queue;
+
+	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
+	if (!queue)
+		return NULL;
+
+	/*
+	 * The WQ is unordered because the low-level handler enqueues faults by
+	 * group. PRI requests within a group have to be ordered, but once
+	 * that's dealt with, the high-level function can handle groups out of
+	 * order.
+	 */
+	queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name);
+	if (!queue->wq) {
+		kfree(queue);
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&queue->devices);
+	mutex_init(&queue->lock);
+
+	return queue;
+}
+EXPORT_SYMBOL_GPL(iopf_queue_alloc);
+
+/**
+ * iopf_queue_free - Free IOPF queue
+ * @queue: queue to free
+ *
+ * Counterpart to iopf_queue_alloc(). The driver must not be queuing faults or
+ * adding/removing devices on this queue anymore.
+ */
+void iopf_queue_free(struct iopf_queue *queue)
+{
+	struct iopf_device_param *iopf_param, *next;
+
+	if (!queue)
+		return;
+
+	list_for_each_entry_safe(iopf_param, next, &queue->devices, queue_list)
+		iopf_queue_remove_device(queue, iopf_param->dev);
+
+	destroy_workqueue(queue->wq);
+	kfree(queue);
+}
+EXPORT_SYMBOL_GPL(iopf_queue_free);
-- 
2.30.1

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iommu@lists.linux-foundation.org
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Jacob Pan]

Hi Jean-Philippe,

A few comments from the p.o.v of converting VT-d to this framework. Mostly
about potential optimization. I think VT-d SVA code will be able to use this
work.
+Ashok provided many insight.

FWIW,
Reviewed-by:Jacob Pan <jacob.jun.pan@linux.intel.com>

On Tue,  2 Mar 2021 10:26:42 +0100, Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:

> Some systems allow devices to handle I/O Page Faults in the core mm. For
> example systems implementing the PCIe PRI extension or Arm SMMU stall
> model. Infrastructure for reporting these recoverable page faults was
> added to the IOMMU core by commit 0c830e6b3282 ("iommu: Introduce device
> fault report API"). Add a page fault handler for host SVA.
> 
> IOMMU driver can now instantiate several fault workqueues and link them
> to IOPF-capable devices. Drivers can choose between a single global
> workqueue, one per IOMMU device, one per low-level fault queue, one per
> domain, etc.
> 
> When it receives a fault event, most commonly in an IRQ handler, the
> IOMMU driver reports the fault using iommu_report_device_fault(), which
> calls the registered handler. The page fault handler then calls the mm
> fault handler, and reports either success or failure with
> iommu_page_response(). After the handler succeeds, the hardware retries
> the access.
> 
> The iopf_param pointer could be embedded into iommu_fault_param. But
> putting iopf_param into the iommu_param structure allows us not to care
> about ordering between calls to iopf_queue_add_device() and
> iommu_register_device_fault_handler().
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  drivers/iommu/Makefile        |   1 +
>  drivers/iommu/iommu-sva-lib.h |  53 ++++
>  include/linux/iommu.h         |   2 +
>  drivers/iommu/io-pgfault.c    | 461 ++++++++++++++++++++++++++++++++++
>  4 files changed, 517 insertions(+)
>  create mode 100644 drivers/iommu/io-pgfault.c
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 61bd30cd8369..60fafc23dee6 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -28,3 +28,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
>  obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
>  obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
>  obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o
> +obj-$(CONFIG_IOMMU_SVA_LIB) += io-pgfault.o
> diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
> index b40990aef3fd..031155010ca8 100644
> --- a/drivers/iommu/iommu-sva-lib.h
> +++ b/drivers/iommu/iommu-sva-lib.h
> @@ -12,4 +12,57 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm,
> ioasid_t min, ioasid_t max); void iommu_sva_free_pasid(struct mm_struct
> *mm); struct mm_struct *iommu_sva_find(ioasid_t pasid);
>  
> +/* I/O Page fault */
> +struct device;
> +struct iommu_fault;
> +struct iopf_queue;
> +
> +#ifdef CONFIG_IOMMU_SVA_LIB
> +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
> +
> +int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev);
> +int iopf_queue_remove_device(struct iopf_queue *queue,
> +			     struct device *dev);
> +int iopf_queue_flush_dev(struct device *dev);
> +struct iopf_queue *iopf_queue_alloc(const char *name);
> +void iopf_queue_free(struct iopf_queue *queue);
> +int iopf_queue_discard_partial(struct iopf_queue *queue);
> +
> +#else /* CONFIG_IOMMU_SVA_LIB */
> +static inline int iommu_queue_iopf(struct iommu_fault *fault, void
> *cookie) +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_add_device(struct iopf_queue *queue,
> +					struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_remove_device(struct iopf_queue *queue,
> +					   struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_flush_dev(struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline struct iopf_queue *iopf_queue_alloc(const char *name)
> +{
> +	return NULL;
> +}
> +
> +static inline void iopf_queue_free(struct iopf_queue *queue)
> +{
> +}
> +
> +static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
> +{
> +	return -ENODEV;
> +}
> +#endif /* CONFIG_IOMMU_SVA_LIB */
>  #endif /* _IOMMU_SVA_LIB_H */
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 45c4eb372f56..86d688c4418f 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -367,6 +367,7 @@ struct iommu_fault_param {
>   * struct dev_iommu - Collection of per-device IOMMU data
>   *
>   * @fault_param: IOMMU detected device fault reporting data
> + * @iopf_param:	 I/O Page Fault queue and data
>   * @fwspec:	 IOMMU fwspec data
>   * @iommu_dev:	 IOMMU device this device is linked to
>   * @priv:	 IOMMU Driver private data
> @@ -377,6 +378,7 @@ struct iommu_fault_param {
>  struct dev_iommu {
>  	struct mutex lock;
>  	struct iommu_fault_param	*fault_param;
> +	struct iopf_device_param	*iopf_param;
>  	struct iommu_fwspec		*fwspec;
>  	struct iommu_device		*iommu_dev;
>  	void				*priv;
> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
> new file mode 100644
> index 000000000000..1df8c1dcae77
> --- /dev/null
> +++ b/drivers/iommu/io-pgfault.c
> @@ -0,0 +1,461 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Handle device page faults
> + *
> + * Copyright (C) 2020 ARM Ltd.
> + */
> +
> +#include <linux/iommu.h>
> +#include <linux/list.h>
> +#include <linux/sched/mm.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +
> +#include "iommu-sva-lib.h"
> +
> +/**
> + * struct iopf_queue - IO Page Fault queue
> + * @wq: the fault workqueue
> + * @devices: devices attached to this queue
> + * @lock: protects the device list
> + */
> +struct iopf_queue {
> +	struct workqueue_struct		*wq;
> +	struct list_head		devices;
> +	struct mutex			lock;
> +};
> +
> +/**
> + * struct iopf_device_param - IO Page Fault data attached to a device
> + * @dev: the device that owns this param
> + * @queue: IOPF queue
> + * @queue_list: index into queue->devices
> + * @partial: faults that are part of a Page Request Group for which the
> last
> + *           request hasn't been submitted yet.
> + */
> +struct iopf_device_param {
> +	struct device			*dev;
> +	struct iopf_queue		*queue;
> +	struct list_head		queue_list;
> +	struct list_head		partial;
> +};
> +
> +struct iopf_fault {
> +	struct iommu_fault		fault;
> +	struct list_head		list;
> +};
> +
> +struct iopf_group {
> +	struct iopf_fault		last_fault;
> +	struct list_head		faults;
> +	struct work_struct		work;
> +	struct device			*dev;
> +};
> +
> +static int iopf_complete_group(struct device *dev, struct iopf_fault
> *iopf,
> +			       enum iommu_page_response_code status)
> +{
> +	struct iommu_page_response resp = {
> +		.version		= IOMMU_PAGE_RESP_VERSION_1,
> +		.pasid			= iopf->fault.prm.pasid,
> +		.grpid			= iopf->fault.prm.grpid,
> +		.code			= status,
> +	};
> +
> +	if ((iopf->fault.prm.flags &
> IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) &&
> +	    (iopf->fault.prm.flags &
> IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID))
> +		resp.flags = IOMMU_PAGE_RESP_PASID_VALID;
> +
> +	return iommu_page_response(dev, &resp);
> +}
> +
> +static enum iommu_page_response_code
> +iopf_handle_single(struct iopf_fault *iopf)
> +{
> +	vm_fault_t ret;
> +	struct mm_struct *mm;
> +	struct vm_area_struct *vma;
> +	unsigned int access_flags = 0;
> +	unsigned int fault_flags = FAULT_FLAG_REMOTE;
> +	struct iommu_fault_page_request *prm = &iopf->fault.prm;
> +	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
> +
> +	if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
> +		return status;
> +
> +	mm = iommu_sva_find(prm->pasid);
> +	if (IS_ERR_OR_NULL(mm))
> +		return status;
> +
> +	mmap_read_lock(mm);
> +
> +	vma = find_extend_vma(mm, prm->addr);
> +	if (!vma)
> +		/* Unmapped area */
> +		goto out_put_mm;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_READ)
> +		access_flags |= VM_READ;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
> +		access_flags |= VM_WRITE;
> +		fault_flags |= FAULT_FLAG_WRITE;
> +	}
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
> +		access_flags |= VM_EXEC;
> +		fault_flags |= FAULT_FLAG_INSTRUCTION;
> +	}
> +
> +	if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
> +		fault_flags |= FAULT_FLAG_USER;
> +
> +	if (access_flags & ~vma->vm_flags)
> +		/* Access fault */
> +		goto out_put_mm;
> +
> +	ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
> +	status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
> +		IOMMU_PAGE_RESP_SUCCESS;
> +
> +out_put_mm:
> +	mmap_read_unlock(mm);
> +	mmput(mm);
> +
> +	return status;
> +}
> +
> +static void iopf_handle_group(struct work_struct *work)
> +{
> +	struct iopf_group *group;
> +	struct iopf_fault *iopf, *next;
> +	enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
> +
> +	group = container_of(work, struct iopf_group, work);
> +
> +	list_for_each_entry_safe(iopf, next, &group->faults, list) {
> +		/*
> +		 * For the moment, errors are sticky: don't handle
> subsequent
> +		 * faults in the group if there is an error.
> +		 */
> +		if (status == IOMMU_PAGE_RESP_SUCCESS)
> +			status = iopf_handle_single(iopf);
> +
> +		if (!(iopf->fault.prm.flags &
> +		      IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
> +			kfree(iopf);
> +	}
> +
> +	iopf_complete_group(group->dev, &group->last_fault, status);
> +	kfree(group);
> +}
> +
> +/**
> + * iommu_queue_iopf - IO Page Fault handler
> + * @fault: fault event
> + * @cookie: struct device, passed to iommu_register_device_fault_handler.
> + *
> + * Add a fault to the device workqueue, to be handled by mm.
> + *
> + * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must
> discard
> + * them before reporting faults. A PASID Stop Marker (LRW = 0b100)
> doesn't
> + * expect a response. It may be generated when disabling a PASID
> (issuing a
> + * PASID stop request) by some PCI devices.
> + *
> + * The PASID stop request is issued by the device driver before
> unbind(). Once
> + * it completes, no page request is generated for this PASID anymore and
> + * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 -
> 6.20.1
> + * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices
> will wait
> + * for all outstanding page requests to come back with a response before
> + * completing the PASID stop request. Others do not wait for page
> responses, and
> + * instead issue this Stop Marker that tells us when the PASID can be
> + * reallocated.
> + *
> + * It is safe to discard the Stop Marker because it is an optimization.
> + * a. Page requests, which are posted requests, have been flushed to the
> IOMMU
> + *    when the stop request completes.
> + * b. The IOMMU driver flushes all fault queues on unbind() before
> freeing the
> + *    PASID.
> + *
> + * So even though the Stop Marker might be issued by the device *after*
> the stop
> + * request completes, outstanding faults will have been dealt with by
> the time
> + * the PASID is freed.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> +{
> +	int ret;
> +	struct iopf_group *group;
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +
> +	struct device *dev = cookie;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	lockdep_assert_held(&param->lock);
> +
> +	if (fault->type != IOMMU_FAULT_PAGE_REQ)
> +		/* Not a recoverable page fault */
> +		return -EOPNOTSUPP;
> +
> +	/*
> +	 * As long as we're holding param->lock, the queue can't be
> unlinked
> +	 * from the device and therefore cannot disappear.
> +	 */
> +	iopf_param = param->iopf_param;
> +	if (!iopf_param)
> +		return -ENODEV;
> +
> +	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
> +		iopf = kzalloc(sizeof(*iopf), GFP_KERNEL);
> +		if (!iopf)
> +			return -ENOMEM;
> +
> +		iopf->fault = *fault;
> +
> +		/* Non-last request of a group. Postpone until the last
> one */
Would be nice to have an option here to allow non-deferred handle_mm_fault.
Some devices may have a large group.

FYI, VT-d also needs to send page response before the last one (LPIG).
"A Page Group Response Descriptor is issued by software in response to a
page request with data or a page request (with or without data) that
indicated that it was the last request in a group."

But I think we deal with that when we convert. Perhaps just treat the
request with data as LPIG.

Also adding a trace event would be nice, similar to CPU page fault.
> +		list_add(&iopf->list, &iopf_param->partial);
> +
> +		return 0;
> +	}
> +
> +	group = kzalloc(sizeof(*group), GFP_KERNEL);
> +	if (!group) {
> +		/*
> +		 * The caller will send a response to the hardware. But
> we do
> +		 * need to clean up before leaving, otherwise partial
> faults
> +		 * will be stuck.
> +		 */
> +		ret = -ENOMEM;
> +		goto cleanup_partial;
> +	}
> +
> +	group->dev = dev;
> +	group->last_fault.fault = *fault;
> +	INIT_LIST_HEAD(&group->faults);
> +	list_add(&group->last_fault.list, &group->faults);
> +	INIT_WORK(&group->work, iopf_handle_group);
> +
> +	/* See if we have partial faults for this group */
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
> {
> +		if (iopf->fault.prm.grpid == fault->prm.grpid)
Just curious, the iopf handler is registered per arm_smmu_master dev. Is
the namespace of group ID also within an arm_smmu_master? Can one
arm_smmu_master support multiple devices?

For VT-d, group ID is per PCI device.

> +			/* Insert *before* the last fault */
> +			list_move(&iopf->list, &group->faults);
> +	}
> +
This is fine with devices supports small number of outstanding PRQs.
VT-d is setting the limit to 32. But the incoming DSA device will support
512.

So if we pre-sort IOPF by group ID and put them in a per group list, would
it be faster? I mean once the LPIG comes in, we just need to search the
list of groups instead of all partial faults. I am not against what is done
here, just exploring optimization.

> +	queue_work(iopf_param->queue->wq, &group->work);
> +	return 0;
> +
> +cleanup_partial:
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
> {
> +		if (iopf->fault.prm.grpid == fault->prm.grpid) {
> +			list_del(&iopf->list);
> +			kfree(iopf);
> +		}
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_queue_iopf);
> +
> +/**
> + * iopf_queue_flush_dev - Ensure that all queued faults have been
> processed
> + * @dev: the endpoint whose faults need to be flushed.
> + *
> + * The IOMMU driver calls this before releasing a PASID, to ensure that
> all
> + * pending faults for this PASID have been handled, and won't hit the
> address
> + * space of the next process that uses this PASID. The driver must make
> sure
> + * that no new fault is added to the queue. In particular it must flush
> its
> + * low-level queue before calling this function.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_flush_dev(struct device *dev)
> +{
> +	int ret = 0;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param)
> +		return -ENODEV;
> +
> +	mutex_lock(&param->lock);
> +	iopf_param = param->iopf_param;
> +	if (iopf_param)
> +		flush_workqueue(iopf_param->queue->wq);
> +	else
> +		ret = -ENODEV;
> +	mutex_unlock(&param->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_flush_dev);
> +
> +/**
> + * iopf_queue_discard_partial - Remove all pending partial fault
> + * @queue: the queue whose partial faults need to be discarded
> + *
> + * When the hardware queue overflows, last page faults in a group may
> have been
> + * lost and the IOMMU driver calls this to discard all partial faults.
> The
> + * driver shouldn't be adding new faults to this queue concurrently.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_discard_partial(struct iopf_queue *queue)
> +{
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +
> +	if (!queue)
> +		return -EINVAL;
> +
> +	mutex_lock(&queue->lock);
> +	list_for_each_entry(iopf_param, &queue->devices, queue_list) {
> +		list_for_each_entry_safe(iopf, next,
> &iopf_param->partial,
> +					 list) {
> +			list_del(&iopf->list);
> +			kfree(iopf);
> +		}
> +	}
> +	mutex_unlock(&queue->lock);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_discard_partial);
> +
> +/**
> + * iopf_queue_add_device - Add producer to the fault queue
> + * @queue: IOPF queue
> + * @dev: device to add
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev)
> +{
> +	int ret = -EBUSY;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param)
> +		return -ENODEV;
> +
> +	iopf_param = kzalloc(sizeof(*iopf_param), GFP_KERNEL);
> +	if (!iopf_param)
> +		return -ENOMEM;
> +
> +	INIT_LIST_HEAD(&iopf_param->partial);
> +	iopf_param->queue = queue;
> +	iopf_param->dev = dev;
> +
> +	mutex_lock(&queue->lock);
> +	mutex_lock(&param->lock);
> +	if (!param->iopf_param) {
> +		list_add(&iopf_param->queue_list, &queue->devices);
> +		param->iopf_param = iopf_param;
> +		ret = 0;
> +	}
> +	mutex_unlock(&param->lock);
> +	mutex_unlock(&queue->lock);
> +
> +	if (ret)
> +		kfree(iopf_param);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_add_device);
> +
> +/**
> + * iopf_queue_remove_device - Remove producer from fault queue
> + * @queue: IOPF queue
> + * @dev: device to remove
> + *
> + * Caller makes sure that no more faults are reported for this device.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_remove_device(struct iopf_queue *queue, struct device
> *dev) +{
> +	int ret = -EINVAL;
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param || !queue)
> +		return -EINVAL;
> +
> +	mutex_lock(&queue->lock);
> +	mutex_lock(&param->lock);
> +	iopf_param = param->iopf_param;
> +	if (iopf_param && iopf_param->queue == queue) {
> +		list_del(&iopf_param->queue_list);
> +		param->iopf_param = NULL;
> +		ret = 0;
> +	}
> +	mutex_unlock(&param->lock);
> +	mutex_unlock(&queue->lock);
> +	if (ret)
> +		return ret;
> +
> +	/* Just in case some faults are still stuck */
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
> +		kfree(iopf);
> +
> +	kfree(iopf_param);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_remove_device);
> +
> +/**
> + * iopf_queue_alloc - Allocate and initialize a fault queue
> + * @name: a unique string identifying the queue (for workqueue)
> + *
> + * Return: the queue on success and NULL on error.
> + */
> +struct iopf_queue *iopf_queue_alloc(const char *name)
> +{
> +	struct iopf_queue *queue;
> +
> +	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
> +	if (!queue)
> +		return NULL;
> +
> +	/*
> +	 * The WQ is unordered because the low-level handler enqueues
> faults by
> +	 * group. PRI requests within a group have to be ordered, but
> once
> +	 * that's dealt with, the high-level function can handle groups
> out of
> +	 * order.
> +	 */
> +	queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0,
> name);
> +	if (!queue->wq) {
> +		kfree(queue);
> +		return NULL;
> +	}
> +
> +	INIT_LIST_HEAD(&queue->devices);
> +	mutex_init(&queue->lock);
> +
> +	return queue;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_alloc);
> +
> +/**
> + * iopf_queue_free - Free IOPF queue
> + * @queue: queue to free
> + *
> + * Counterpart to iopf_queue_alloc(). The driver must not be queuing
> faults or
> + * adding/removing devices on this queue anymore.
> + */
> +void iopf_queue_free(struct iopf_queue *queue)
> +{
> +	struct iopf_device_param *iopf_param, *next;
> +
> +	if (!queue)
> +		return;
> +
> +	list_for_each_entry_safe(iopf_param, next, &queue->devices,
> queue_list)
> +		iopf_queue_remove_device(queue, iopf_param->dev);
> +
> +	destroy_workqueue(queue->wq);
> +	kfree(queue);
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_free);


Thanks,

Jacob
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Jean-Philippe Brucker]

On Tue, Mar 02, 2021 at 03:59:57PM -0800, Jacob Pan wrote:
> Hi Jean-Philippe,
> 
> A few comments from the p.o.v of converting VT-d to this framework. Mostly
> about potential optimization. I think VT-d SVA code will be able to use this
> work.
> +Ashok provided many insight.
> 
> FWIW,
> Reviewed-by:Jacob Pan <jacob.jun.pan@linux.intel.com>

Thanks!

> On Tue,  2 Mar 2021 10:26:42 +0100, Jean-Philippe Brucker
> <jean-philippe@linaro.org> wrote:
> > +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> > +{
> > +	int ret;
> > +	struct iopf_group *group;
> > +	struct iopf_fault *iopf, *next;
> > +	struct iopf_device_param *iopf_param;
> > +
> > +	struct device *dev = cookie;
> > +	struct dev_iommu *param = dev->iommu;
> > +
> > +	lockdep_assert_held(&param->lock);
> > +
> > +	if (fault->type != IOMMU_FAULT_PAGE_REQ)
> > +		/* Not a recoverable page fault */
> > +		return -EOPNOTSUPP;
> > +
> > +	/*
> > +	 * As long as we're holding param->lock, the queue can't be
> > unlinked
> > +	 * from the device and therefore cannot disappear.
> > +	 */
> > +	iopf_param = param->iopf_param;
> > +	if (!iopf_param)
> > +		return -ENODEV;
> > +
> > +	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
> > +		iopf = kzalloc(sizeof(*iopf), GFP_KERNEL);
> > +		if (!iopf)
> > +			return -ENOMEM;
> > +
> > +		iopf->fault = *fault;
> > +
> > +		/* Non-last request of a group. Postpone until the last
> > one */
> Would be nice to have an option here to allow non-deferred handle_mm_fault.
> Some devices may have a large group.
> 
> FYI, VT-d also needs to send page response before the last one (LPIG).
> "A Page Group Response Descriptor is issued by software in response to a
> page request with data or a page request (with or without data) that
> indicated that it was the last request in a group."
> 
> But I think we deal with that when we convert. Perhaps just treat the
> request with data as LPIG.

Sure that seems fine. Do you mean that the vt-d driver will set the
IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE flag for PR-with-data?  Otherwise we
could introduce a new flag. I prefer making it explicit rather than having
IOPF consumers infer that a response is needed when seeing
IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA set, because private_data wouldn't be
reusable by other architectures.

> Also adding a trace event would be nice, similar to CPU page fault.

Agreed, the tracepoints in my development tree (along with the lower-level
page_request/response tracepoints) have been indispensable for debugging
hardware and SVA applications

> > +		list_add(&iopf->list, &iopf_param->partial);
> > +
> > +		return 0;
> > +	}
> > +
> > +	group = kzalloc(sizeof(*group), GFP_KERNEL);
> > +	if (!group) {
> > +		/*
> > +		 * The caller will send a response to the hardware. But
> > we do
> > +		 * need to clean up before leaving, otherwise partial
> > faults
> > +		 * will be stuck.
> > +		 */
> > +		ret = -ENOMEM;
> > +		goto cleanup_partial;
> > +	}
> > +
> > +	group->dev = dev;
> > +	group->last_fault.fault = *fault;
> > +	INIT_LIST_HEAD(&group->faults);
> > +	list_add(&group->last_fault.list, &group->faults);
> > +	INIT_WORK(&group->work, iopf_handle_group);
> > +
> > +	/* See if we have partial faults for this group */
> > +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
> > {
> > +		if (iopf->fault.prm.grpid == fault->prm.grpid)
> Just curious, the iopf handler is registered per arm_smmu_master dev. Is
> the namespace of group ID also within an arm_smmu_master?

Yes for both PCIe PRI and SMMU stall, the namespace is within one device
(one RequesterID or StreamID)

> Can one arm_smmu_master support multiple devices?

No, it's a single device

> 
> For VT-d, group ID is per PCI device.
> 
> > +			/* Insert *before* the last fault */
> > +			list_move(&iopf->list, &group->faults);
> > +	}
> > +
> This is fine with devices supports small number of outstanding PRQs.
> VT-d is setting the limit to 32. But the incoming DSA device will support
> 512.
> 
> So if we pre-sort IOPF by group ID and put them in a per group list, would
> it be faster? I mean once the LPIG comes in, we just need to search the
> list of groups instead of all partial faults. I am not against what is done
> here, just exploring optimization.

Yes I think that's worth exploring, keeping the groups in a rb_tree or something
like that, for easy access and update. Note that I don't have a system
with non-LPIG faults, so I can't test any of this at the moment

Thanks,
Jean
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Lu Baolu]

Hi Jean,

On 3/2/21 5:26 PM, Jean-Philippe Brucker wrote:
> Some systems allow devices to handle I/O Page Faults in the core mm. For
> example systems implementing the PCIe PRI extension or Arm SMMU stall
> model. Infrastructure for reporting these recoverable page faults was
> added to the IOMMU core by commit 0c830e6b3282 ("iommu: Introduce device
> fault report API"). Add a page fault handler for host SVA.
> 
> IOMMU driver can now instantiate several fault workqueues and link them
> to IOPF-capable devices. Drivers can choose between a single global
> workqueue, one per IOMMU device, one per low-level fault queue, one per
> domain, etc.
> 
> When it receives a fault event, most commonly in an IRQ handler, the
> IOMMU driver reports the fault using iommu_report_device_fault(), which
> calls the registered handler. The page fault handler then calls the mm
> fault handler, and reports either success or failure with
> iommu_page_response(). After the handler succeeds, the hardware retries
> the access.
> 
> The iopf_param pointer could be embedded into iommu_fault_param. But
> putting iopf_param into the iommu_param structure allows us not to care
> about ordering between calls to iopf_queue_add_device() and
> iommu_register_device_fault_handler().
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

I have tested this framework with the Intel VT-d implementation. It
works as expected. Hence,

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Lu Baolu <baolu.lu@linux.intel.com>

One possible future optimization is that we could allow the system
administrators to choose between handle PRQs in a workqueue or handle
them synchronously. One research discovered that most of the software
latency of handling a single page fault exists in the schedule part.
Hence, synchronous processing will get shorter software latency if PRQs
are rare and limited.

Best regards,
baolu

> ---
>   drivers/iommu/Makefile        |   1 +
>   drivers/iommu/iommu-sva-lib.h |  53 ++++
>   include/linux/iommu.h         |   2 +
>   drivers/iommu/io-pgfault.c    | 461 ++++++++++++++++++++++++++++++++++
>   4 files changed, 517 insertions(+)
>   create mode 100644 drivers/iommu/io-pgfault.c
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 61bd30cd8369..60fafc23dee6 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -28,3 +28,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
>   obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
>   obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
>   obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o
> +obj-$(CONFIG_IOMMU_SVA_LIB) += io-pgfault.o
> diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
> index b40990aef3fd..031155010ca8 100644
> --- a/drivers/iommu/iommu-sva-lib.h
> +++ b/drivers/iommu/iommu-sva-lib.h
> @@ -12,4 +12,57 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
>   void iommu_sva_free_pasid(struct mm_struct *mm);
>   struct mm_struct *iommu_sva_find(ioasid_t pasid);
>   
> +/* I/O Page fault */
> +struct device;
> +struct iommu_fault;
> +struct iopf_queue;
> +
> +#ifdef CONFIG_IOMMU_SVA_LIB
> +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
> +
> +int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev);
> +int iopf_queue_remove_device(struct iopf_queue *queue,
> +			     struct device *dev);
> +int iopf_queue_flush_dev(struct device *dev);
> +struct iopf_queue *iopf_queue_alloc(const char *name);
> +void iopf_queue_free(struct iopf_queue *queue);
> +int iopf_queue_discard_partial(struct iopf_queue *queue);
> +
> +#else /* CONFIG_IOMMU_SVA_LIB */
> +static inline int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_add_device(struct iopf_queue *queue,
> +					struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_remove_device(struct iopf_queue *queue,
> +					   struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iopf_queue_flush_dev(struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline struct iopf_queue *iopf_queue_alloc(const char *name)
> +{
> +	return NULL;
> +}
> +
> +static inline void iopf_queue_free(struct iopf_queue *queue)
> +{
> +}
> +
> +static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
> +{
> +	return -ENODEV;
> +}
> +#endif /* CONFIG_IOMMU_SVA_LIB */
>   #endif /* _IOMMU_SVA_LIB_H */
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 45c4eb372f56..86d688c4418f 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -367,6 +367,7 @@ struct iommu_fault_param {
>    * struct dev_iommu - Collection of per-device IOMMU data
>    *
>    * @fault_param: IOMMU detected device fault reporting data
> + * @iopf_param:	 I/O Page Fault queue and data
>    * @fwspec:	 IOMMU fwspec data
>    * @iommu_dev:	 IOMMU device this device is linked to
>    * @priv:	 IOMMU Driver private data
> @@ -377,6 +378,7 @@ struct iommu_fault_param {
>   struct dev_iommu {
>   	struct mutex lock;
>   	struct iommu_fault_param	*fault_param;
> +	struct iopf_device_param	*iopf_param;
>   	struct iommu_fwspec		*fwspec;
>   	struct iommu_device		*iommu_dev;
>   	void				*priv;
> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
> new file mode 100644
> index 000000000000..1df8c1dcae77
> --- /dev/null
> +++ b/drivers/iommu/io-pgfault.c
> @@ -0,0 +1,461 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Handle device page faults
> + *
> + * Copyright (C) 2020 ARM Ltd.
> + */
> +
> +#include <linux/iommu.h>
> +#include <linux/list.h>
> +#include <linux/sched/mm.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +
> +#include "iommu-sva-lib.h"
> +
> +/**
> + * struct iopf_queue - IO Page Fault queue
> + * @wq: the fault workqueue
> + * @devices: devices attached to this queue
> + * @lock: protects the device list
> + */
> +struct iopf_queue {
> +	struct workqueue_struct		*wq;
> +	struct list_head		devices;
> +	struct mutex			lock;
> +};
> +
> +/**
> + * struct iopf_device_param - IO Page Fault data attached to a device
> + * @dev: the device that owns this param
> + * @queue: IOPF queue
> + * @queue_list: index into queue->devices
> + * @partial: faults that are part of a Page Request Group for which the last
> + *           request hasn't been submitted yet.
> + */
> +struct iopf_device_param {
> +	struct device			*dev;
> +	struct iopf_queue		*queue;
> +	struct list_head		queue_list;
> +	struct list_head		partial;
> +};
> +
> +struct iopf_fault {
> +	struct iommu_fault		fault;
> +	struct list_head		list;
> +};
> +
> +struct iopf_group {
> +	struct iopf_fault		last_fault;
> +	struct list_head		faults;
> +	struct work_struct		work;
> +	struct device			*dev;
> +};
> +
> +static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf,
> +			       enum iommu_page_response_code status)
> +{
> +	struct iommu_page_response resp = {
> +		.version		= IOMMU_PAGE_RESP_VERSION_1,
> +		.pasid			= iopf->fault.prm.pasid,
> +		.grpid			= iopf->fault.prm.grpid,
> +		.code			= status,
> +	};
> +
> +	if ((iopf->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) &&
> +	    (iopf->fault.prm.flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID))
> +		resp.flags = IOMMU_PAGE_RESP_PASID_VALID;
> +
> +	return iommu_page_response(dev, &resp);
> +}
> +
> +static enum iommu_page_response_code
> +iopf_handle_single(struct iopf_fault *iopf)
> +{
> +	vm_fault_t ret;
> +	struct mm_struct *mm;
> +	struct vm_area_struct *vma;
> +	unsigned int access_flags = 0;
> +	unsigned int fault_flags = FAULT_FLAG_REMOTE;
> +	struct iommu_fault_page_request *prm = &iopf->fault.prm;
> +	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
> +
> +	if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
> +		return status;
> +
> +	mm = iommu_sva_find(prm->pasid);
> +	if (IS_ERR_OR_NULL(mm))
> +		return status;
> +
> +	mmap_read_lock(mm);
> +
> +	vma = find_extend_vma(mm, prm->addr);
> +	if (!vma)
> +		/* Unmapped area */
> +		goto out_put_mm;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_READ)
> +		access_flags |= VM_READ;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
> +		access_flags |= VM_WRITE;
> +		fault_flags |= FAULT_FLAG_WRITE;
> +	}
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
> +		access_flags |= VM_EXEC;
> +		fault_flags |= FAULT_FLAG_INSTRUCTION;
> +	}
> +
> +	if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
> +		fault_flags |= FAULT_FLAG_USER;
> +
> +	if (access_flags & ~vma->vm_flags)
> +		/* Access fault */
> +		goto out_put_mm;
> +
> +	ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
> +	status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
> +		IOMMU_PAGE_RESP_SUCCESS;
> +
> +out_put_mm:
> +	mmap_read_unlock(mm);
> +	mmput(mm);
> +
> +	return status;
> +}
> +
> +static void iopf_handle_group(struct work_struct *work)
> +{
> +	struct iopf_group *group;
> +	struct iopf_fault *iopf, *next;
> +	enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
> +
> +	group = container_of(work, struct iopf_group, work);
> +
> +	list_for_each_entry_safe(iopf, next, &group->faults, list) {
> +		/*
> +		 * For the moment, errors are sticky: don't handle subsequent
> +		 * faults in the group if there is an error.
> +		 */
> +		if (status == IOMMU_PAGE_RESP_SUCCESS)
> +			status = iopf_handle_single(iopf);
> +
> +		if (!(iopf->fault.prm.flags &
> +		      IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
> +			kfree(iopf);
> +	}
> +
> +	iopf_complete_group(group->dev, &group->last_fault, status);
> +	kfree(group);
> +}
> +
> +/**
> + * iommu_queue_iopf - IO Page Fault handler
> + * @fault: fault event
> + * @cookie: struct device, passed to iommu_register_device_fault_handler.
> + *
> + * Add a fault to the device workqueue, to be handled by mm.
> + *
> + * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
> + * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
> + * expect a response. It may be generated when disabling a PASID (issuing a
> + * PASID stop request) by some PCI devices.
> + *
> + * The PASID stop request is issued by the device driver before unbind(). Once
> + * it completes, no page request is generated for this PASID anymore and
> + * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 - 6.20.1
> + * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices will wait
> + * for all outstanding page requests to come back with a response before
> + * completing the PASID stop request. Others do not wait for page responses, and
> + * instead issue this Stop Marker that tells us when the PASID can be
> + * reallocated.
> + *
> + * It is safe to discard the Stop Marker because it is an optimization.
> + * a. Page requests, which are posted requests, have been flushed to the IOMMU
> + *    when the stop request completes.
> + * b. The IOMMU driver flushes all fault queues on unbind() before freeing the
> + *    PASID.
> + *
> + * So even though the Stop Marker might be issued by the device *after* the stop
> + * request completes, outstanding faults will have been dealt with by the time
> + * the PASID is freed.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> +{
> +	int ret;
> +	struct iopf_group *group;
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +
> +	struct device *dev = cookie;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	lockdep_assert_held(&param->lock);
> +
> +	if (fault->type != IOMMU_FAULT_PAGE_REQ)
> +		/* Not a recoverable page fault */
> +		return -EOPNOTSUPP;
> +
> +	/*
> +	 * As long as we're holding param->lock, the queue can't be unlinked
> +	 * from the device and therefore cannot disappear.
> +	 */
> +	iopf_param = param->iopf_param;
> +	if (!iopf_param)
> +		return -ENODEV;
> +
> +	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
> +		iopf = kzalloc(sizeof(*iopf), GFP_KERNEL);
> +		if (!iopf)
> +			return -ENOMEM;
> +
> +		iopf->fault = *fault;
> +
> +		/* Non-last request of a group. Postpone until the last one */
> +		list_add(&iopf->list, &iopf_param->partial);
> +
> +		return 0;
> +	}
> +
> +	group = kzalloc(sizeof(*group), GFP_KERNEL);
> +	if (!group) {
> +		/*
> +		 * The caller will send a response to the hardware. But we do
> +		 * need to clean up before leaving, otherwise partial faults
> +		 * will be stuck.
> +		 */
> +		ret = -ENOMEM;
> +		goto cleanup_partial;
> +	}
> +
> +	group->dev = dev;
> +	group->last_fault.fault = *fault;
> +	INIT_LIST_HEAD(&group->faults);
> +	list_add(&group->last_fault.list, &group->faults);
> +	INIT_WORK(&group->work, iopf_handle_group);
> +
> +	/* See if we have partial faults for this group */
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
> +		if (iopf->fault.prm.grpid == fault->prm.grpid)
> +			/* Insert *before* the last fault */
> +			list_move(&iopf->list, &group->faults);
> +	}
> +
> +	queue_work(iopf_param->queue->wq, &group->work);
> +	return 0;
> +
> +cleanup_partial:
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
> +		if (iopf->fault.prm.grpid == fault->prm.grpid) {
> +			list_del(&iopf->list);
> +			kfree(iopf);
> +		}
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_queue_iopf);
> +
> +/**
> + * iopf_queue_flush_dev - Ensure that all queued faults have been processed
> + * @dev: the endpoint whose faults need to be flushed.
> + *
> + * The IOMMU driver calls this before releasing a PASID, to ensure that all
> + * pending faults for this PASID have been handled, and won't hit the address
> + * space of the next process that uses this PASID. The driver must make sure
> + * that no new fault is added to the queue. In particular it must flush its
> + * low-level queue before calling this function.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_flush_dev(struct device *dev)
> +{
> +	int ret = 0;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param)
> +		return -ENODEV;
> +
> +	mutex_lock(&param->lock);
> +	iopf_param = param->iopf_param;
> +	if (iopf_param)
> +		flush_workqueue(iopf_param->queue->wq);
> +	else
> +		ret = -ENODEV;
> +	mutex_unlock(&param->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_flush_dev);
> +
> +/**
> + * iopf_queue_discard_partial - Remove all pending partial fault
> + * @queue: the queue whose partial faults need to be discarded
> + *
> + * When the hardware queue overflows, last page faults in a group may have been
> + * lost and the IOMMU driver calls this to discard all partial faults. The
> + * driver shouldn't be adding new faults to this queue concurrently.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_discard_partial(struct iopf_queue *queue)
> +{
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +
> +	if (!queue)
> +		return -EINVAL;
> +
> +	mutex_lock(&queue->lock);
> +	list_for_each_entry(iopf_param, &queue->devices, queue_list) {
> +		list_for_each_entry_safe(iopf, next, &iopf_param->partial,
> +					 list) {
> +			list_del(&iopf->list);
> +			kfree(iopf);
> +		}
> +	}
> +	mutex_unlock(&queue->lock);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_discard_partial);
> +
> +/**
> + * iopf_queue_add_device - Add producer to the fault queue
> + * @queue: IOPF queue
> + * @dev: device to add
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev)
> +{
> +	int ret = -EBUSY;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param)
> +		return -ENODEV;
> +
> +	iopf_param = kzalloc(sizeof(*iopf_param), GFP_KERNEL);
> +	if (!iopf_param)
> +		return -ENOMEM;
> +
> +	INIT_LIST_HEAD(&iopf_param->partial);
> +	iopf_param->queue = queue;
> +	iopf_param->dev = dev;
> +
> +	mutex_lock(&queue->lock);
> +	mutex_lock(&param->lock);
> +	if (!param->iopf_param) {
> +		list_add(&iopf_param->queue_list, &queue->devices);
> +		param->iopf_param = iopf_param;
> +		ret = 0;
> +	}
> +	mutex_unlock(&param->lock);
> +	mutex_unlock(&queue->lock);
> +
> +	if (ret)
> +		kfree(iopf_param);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_add_device);
> +
> +/**
> + * iopf_queue_remove_device - Remove producer from fault queue
> + * @queue: IOPF queue
> + * @dev: device to remove
> + *
> + * Caller makes sure that no more faults are reported for this device.
> + *
> + * Return: 0 on success and <0 on error.
> + */
> +int iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev)
> +{
> +	int ret = -EINVAL;
> +	struct iopf_fault *iopf, *next;
> +	struct iopf_device_param *iopf_param;
> +	struct dev_iommu *param = dev->iommu;
> +
> +	if (!param || !queue)
> +		return -EINVAL;
> +
> +	mutex_lock(&queue->lock);
> +	mutex_lock(&param->lock);
> +	iopf_param = param->iopf_param;
> +	if (iopf_param && iopf_param->queue == queue) {
> +		list_del(&iopf_param->queue_list);
> +		param->iopf_param = NULL;
> +		ret = 0;
> +	}
> +	mutex_unlock(&param->lock);
> +	mutex_unlock(&queue->lock);
> +	if (ret)
> +		return ret;
> +
> +	/* Just in case some faults are still stuck */
> +	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
> +		kfree(iopf);
> +
> +	kfree(iopf_param);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_remove_device);
> +
> +/**
> + * iopf_queue_alloc - Allocate and initialize a fault queue
> + * @name: a unique string identifying the queue (for workqueue)
> + *
> + * Return: the queue on success and NULL on error.
> + */
> +struct iopf_queue *iopf_queue_alloc(const char *name)
> +{
> +	struct iopf_queue *queue;
> +
> +	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
> +	if (!queue)
> +		return NULL;
> +
> +	/*
> +	 * The WQ is unordered because the low-level handler enqueues faults by
> +	 * group. PRI requests within a group have to be ordered, but once
> +	 * that's dealt with, the high-level function can handle groups out of
> +	 * order.
> +	 */
> +	queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name);
> +	if (!queue->wq) {
> +		kfree(queue);
> +		return NULL;
> +	}
> +
> +	INIT_LIST_HEAD(&queue->devices);
> +	mutex_init(&queue->lock);
> +
> +	return queue;
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_alloc);
> +
> +/**
> + * iopf_queue_free - Free IOPF queue
> + * @queue: queue to free
> + *
> + * Counterpart to iopf_queue_alloc(). The driver must not be queuing faults or
> + * adding/removing devices on this queue anymore.
> + */
> +void iopf_queue_free(struct iopf_queue *queue)
> +{
> +	struct iopf_device_param *iopf_param, *next;
> +
> +	if (!queue)
> +		return;
> +
> +	list_for_each_entry_safe(iopf_param, next, &queue->devices, queue_list)
> +		iopf_queue_remove_device(queue, iopf_param->dev);
> +
> +	destroy_workqueue(queue->wq);
> +	kfree(queue);
> +}
> +EXPORT_SYMBOL_GPL(iopf_queue_free);
> 
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Jean-Philippe Brucker]

On Wed, Mar 03, 2021 at 01:27:34PM +0800, Lu Baolu wrote:
> I have tested this framework with the Intel VT-d implementation. It
> works as expected. Hence,
> 
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Tested-by: Lu Baolu <baolu.lu@linux.intel.com>

Thanks!

> One possible future optimization is that we could allow the system
> administrators to choose between handle PRQs in a workqueue or handle
> them synchronously. One research discovered that most of the software
> latency of handling a single page fault exists in the schedule part.
> Hence, synchronous processing will get shorter software latency if PRQs
> are rare and limited.

Yes, the risk is that processing a fault synchronously will take too much
time, leading to PRI queue overflow if the IOMMU keeps receiving page
faults. That's why I opted for the workqueue initially, but it's
definitely something we can tweak

Thanks,
Jean
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Raj, Ashok]

On Tue, Mar 02, 2021 at 10:26:42AM +0100, Jean-Philippe Brucker wrote:
[snip]

> +
> +static enum iommu_page_response_code
> +iopf_handle_single(struct iopf_fault *iopf)
> +{
> +	vm_fault_t ret;
> +	struct mm_struct *mm;
> +	struct vm_area_struct *vma;
> +	unsigned int access_flags = 0;
> +	unsigned int fault_flags = FAULT_FLAG_REMOTE;
> +	struct iommu_fault_page_request *prm = &iopf->fault.prm;
> +	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
> +
> +	if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
> +		return status;
> +
> +	mm = iommu_sva_find(prm->pasid);
> +	if (IS_ERR_OR_NULL(mm))
> +		return status;
> +
> +	mmap_read_lock(mm);
> +
> +	vma = find_extend_vma(mm, prm->addr);
> +	if (!vma)
> +		/* Unmapped area */
> +		goto out_put_mm;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_READ)
> +		access_flags |= VM_READ;
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
> +		access_flags |= VM_WRITE;
> +		fault_flags |= FAULT_FLAG_WRITE;
> +	}
> +
> +	if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
> +		access_flags |= VM_EXEC;
> +		fault_flags |= FAULT_FLAG_INSTRUCTION;
> +	}
> +
> +	if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
> +		fault_flags |= FAULT_FLAG_USER;
> +
> +	if (access_flags & ~vma->vm_flags)
> +		/* Access fault */
> +		goto out_put_mm;
> +
> +	ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);

Should we add a trace similar to trace_page_fault_user() or kernel in
arch/x86/kernel/mm/fault.c 

or maybe add a perf_sw_event() for device faults? 

Cheers,
Ashok
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Re: [PATCH v13 06/10] iommu: Add a page fault handler

[Jean-Philippe Brucker]

On Tue, Mar 02, 2021 at 09:57:27PM -0800, Raj, Ashok wrote:
> > +	ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
> 
> Should we add a trace similar to trace_page_fault_user() or kernel in
> arch/x86/kernel/mm/fault.c 

Yes that would definitely be useful for debugging hardware and developping
applications. I can send a separate patch to add tracepoints here and in
the lower-level device fault path.

> or maybe add a perf_sw_event() for device faults? 

It does seem like that would fit well alongside the existing
PERF_COUNT_SW_PAGE_FAULTS, but I don't think it would be useful in
practice, because we can't provide a context for the event. Since we're
handling these faults remotely, the only way for a user to get IOPF events
is to enable them on all CPUs and all tasks. Tracepoints can have 'pasid'
and 'device' fields to identify an event, but the perf_sw_event wouldn't
have any useful metadata apart from the faulting address.

We could also add tracepoints on bind(), so users can get the PASID
obtained with the PID they care about and filter fault events based on
that.

I've been wondering about associating a PASID with a PID internally,
because we don't currently have anywhere to send SEGV signals for
unhandled page faults. But I think it would be best to notify the device
driver on unhandled fault and let them deal with it. They'll probably want
that information anyway.

Thanks,
Jean
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[PATCH v13 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure

[Jean-Philippe Brucker]

When handling faults from the event or PRI queue, we need to find the
struct device associated with a SID. Add a rb_tree to keep track of
SIDs.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  13 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 157 ++++++++++++++++----
 2 files changed, 140 insertions(+), 30 deletions(-)

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 f985817c967a..7b15b7580c6e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -639,6 +639,15 @@ struct arm_smmu_device {
 
 	/* IOMMU core code handle */
 	struct iommu_device		iommu;
+
+	struct rb_root			streams;
+	struct mutex			streams_mutex;
+};
+
+struct arm_smmu_stream {
+	u32				id;
+	struct arm_smmu_master		*master;
+	struct rb_node			node;
 };
 
 /* SMMU private data for each master */
@@ -647,8 +656,8 @@ struct arm_smmu_master {
 	struct device			*dev;
 	struct arm_smmu_domain		*domain;
 	struct list_head		domain_head;
-	u32				*sids;
-	unsigned int			num_sids;
+	struct arm_smmu_stream		*streams;
+	unsigned int			num_streams;
 	bool				ats_enabled;
 	bool				sva_enabled;
 	struct list_head		bonds;
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 7edce914c45e..d148bb6d4289 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -909,8 +909,8 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 
 	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
 	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
-		for (i = 0; i < master->num_sids; i++) {
-			cmd.cfgi.sid = master->sids[i];
+		for (i = 0; i < master->num_streams; i++) {
+			cmd.cfgi.sid = master->streams[i].id;
 			arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
 		}
 	}
@@ -1355,6 +1355,28 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
 	return 0;
 }
 
+/* smmu->streams_mutex must be held */
+__maybe_unused
+static struct arm_smmu_master *
+arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
+{
+	struct rb_node *node;
+	struct arm_smmu_stream *stream;
+
+	node = smmu->streams.rb_node;
+	while (node) {
+		stream = rb_entry(node, struct arm_smmu_stream, node);
+		if (stream->id < sid)
+			node = node->rb_right;
+		else if (stream->id > sid)
+			node = node->rb_left;
+		else
+			return stream->master;
+	}
+
+	return NULL;
+}
+
 /* IRQ and event handlers */
 static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
 {
@@ -1588,8 +1610,8 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
 
 	arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
 
-	for (i = 0; i < master->num_sids; i++) {
-		cmd.atc.sid = master->sids[i];
+	for (i = 0; i < master->num_streams; i++) {
+		cmd.atc.sid = master->streams[i].id;
 		arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
 	}
 
@@ -1632,8 +1654,8 @@ int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,
 		if (!master->ats_enabled)
 			continue;
 
-		for (i = 0; i < master->num_sids; i++) {
-			cmd.atc.sid = master->sids[i];
+		for (i = 0; i < master->num_streams; i++) {
+			cmd.atc.sid = master->streams[i].id;
 			arm_smmu_cmdq_batch_add(smmu_domain->smmu, &cmds, &cmd);
 		}
 	}
@@ -2065,13 +2087,13 @@ static void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master)
 	int i, j;
 	struct arm_smmu_device *smmu = master->smmu;
 
-	for (i = 0; i < master->num_sids; ++i) {
-		u32 sid = master->sids[i];
+	for (i = 0; i < master->num_streams; ++i) {
+		u32 sid = master->streams[i].id;
 		__le64 *step = arm_smmu_get_step_for_sid(smmu, sid);
 
 		/* Bridged PCI devices may end up with duplicated IDs */
 		for (j = 0; j < i; j++)
-			if (master->sids[j] == sid)
+			if (master->streams[j].id == sid)
 				break;
 		if (j < i)
 			continue;
@@ -2345,11 +2367,101 @@ static bool arm_smmu_sid_in_range(struct arm_smmu_device *smmu, u32 sid)
 	return sid < limit;
 }
 
+static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
+				  struct arm_smmu_master *master)
+{
+	int i;
+	int ret = 0;
+	struct arm_smmu_stream *new_stream, *cur_stream;
+	struct rb_node **new_node, *parent_node = NULL;
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
+
+	master->streams = kcalloc(fwspec->num_ids, sizeof(*master->streams),
+				  GFP_KERNEL);
+	if (!master->streams)
+		return -ENOMEM;
+	master->num_streams = fwspec->num_ids;
+
+	mutex_lock(&smmu->streams_mutex);
+	for (i = 0; i < fwspec->num_ids; i++) {
+		u32 sid = fwspec->ids[i];
+
+		new_stream = &master->streams[i];
+		new_stream->id = sid;
+		new_stream->master = master;
+
+		/*
+		 * Check the SIDs are in range of the SMMU and our stream table
+		 */
+		if (!arm_smmu_sid_in_range(smmu, sid)) {
+			ret = -ERANGE;
+			break;
+		}
+
+		/* Ensure l2 strtab is initialised */
+		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
+			ret = arm_smmu_init_l2_strtab(smmu, sid);
+			if (ret)
+				break;
+		}
+
+		/* Insert into SID tree */
+		new_node = &(smmu->streams.rb_node);
+		while (*new_node) {
+			cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
+					      node);
+			parent_node = *new_node;
+			if (cur_stream->id > new_stream->id) {
+				new_node = &((*new_node)->rb_left);
+			} else if (cur_stream->id < new_stream->id) {
+				new_node = &((*new_node)->rb_right);
+			} else {
+				dev_warn(master->dev,
+					 "stream %u already in tree\n",
+					 cur_stream->id);
+				ret = -EINVAL;
+				break;
+			}
+		}
+		if (ret)
+			break;
+
+		rb_link_node(&new_stream->node, parent_node, new_node);
+		rb_insert_color(&new_stream->node, &smmu->streams);
+	}
+
+	if (ret) {
+		for (i--; i >= 0; i--)
+			rb_erase(&master->streams[i].node, &smmu->streams);
+		kfree(master->streams);
+	}
+	mutex_unlock(&smmu->streams_mutex);
+
+	return ret;
+}
+
+static void arm_smmu_remove_master(struct arm_smmu_master *master)
+{
+	int i;
+	struct arm_smmu_device *smmu = master->smmu;
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
+
+	if (!smmu || !master->streams)
+		return;
+
+	mutex_lock(&smmu->streams_mutex);
+	for (i = 0; i < fwspec->num_ids; i++)
+		rb_erase(&master->streams[i].node, &smmu->streams);
+	mutex_unlock(&smmu->streams_mutex);
+
+	kfree(master->streams);
+}
+
 static struct iommu_ops arm_smmu_ops;
 
 static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 {
-	int i, ret;
+	int ret;
 	struct arm_smmu_device *smmu;
 	struct arm_smmu_master *master;
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
@@ -2370,27 +2482,12 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 
 	master->dev = dev;
 	master->smmu = smmu;
-	master->sids = fwspec->ids;
-	master->num_sids = fwspec->num_ids;
 	INIT_LIST_HEAD(&master->bonds);
 	dev_iommu_priv_set(dev, master);
 
-	/* Check the SIDs are in range of the SMMU and our stream table */
-	for (i = 0; i < master->num_sids; i++) {
-		u32 sid = master->sids[i];
-
-		if (!arm_smmu_sid_in_range(smmu, sid)) {
-			ret = -ERANGE;
-			goto err_free_master;
-		}
-
-		/* Ensure l2 strtab is initialised */
-		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
-			ret = arm_smmu_init_l2_strtab(smmu, sid);
-			if (ret)
-				goto err_free_master;
-		}
-	}
+	ret = arm_smmu_insert_master(smmu, master);
+	if (ret)
+		goto err_free_master;
 
 	device_property_read_u32(dev, "pasid-num-bits", &master->ssid_bits);
 	master->ssid_bits = min(smmu->ssid_bits, master->ssid_bits);
@@ -2429,6 +2526,7 @@ static void arm_smmu_release_device(struct device *dev)
 	WARN_ON(arm_smmu_master_sva_enabled(master));
 	arm_smmu_detach_dev(master);
 	arm_smmu_disable_pasid(master);
+	arm_smmu_remove_master(master);
 	kfree(master);
 	iommu_fwspec_free(dev);
 }
@@ -2852,6 +2950,9 @@ static int arm_smmu_init_structures(struct arm_smmu_device *smmu)
 {
 	int ret;
 
+	mutex_init(&smmu->streams_mutex);
+	smmu->streams = RB_ROOT;
+
 	ret = arm_smmu_init_queues(smmu);
 	if (ret)
 		return ret;
-- 
2.30.1

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Re: [PATCH v13 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure

[Keqian Zhu]

Hi Jean,

Reviewed-by: Keqian Zhu <zhukeqian1@huawei.com>

On 2021/3/2 17:26, Jean-Philippe Brucker wrote:
> When handling faults from the event or PRI queue, we need to find the
> struct device associated with a SID. Add a rb_tree to keep track of
> SIDs.
> 
> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  13 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 157 ++++++++++++++++----
>  2 files changed, 140 insertions(+), 30 deletions(-)
> 
> 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 f985817c967a..7b15b7580c6e 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -639,6 +639,15 @@ struct arm_smmu_device {
>  
>  	/* IOMMU core code handle */
>  	struct iommu_device		iommu;
> +
> +	struct rb_root			streams;
> +	struct mutex			streams_mutex;
> +};
> +
> +struct arm_smmu_stream {
> +	u32				id;
> +	struct arm_smmu_master		*master;
> +	struct rb_node			node;
>  };
>  
>  /* SMMU private data for each master */
> @@ -647,8 +656,8 @@ struct arm_smmu_master {
>  	struct device			*dev;
>  	struct arm_smmu_domain		*domain;
>  	struct list_head		domain_head;
> -	u32				*sids;
> -	unsigned int			num_sids;
> +	struct arm_smmu_stream		*streams;
> +	unsigned int			num_streams;
>  	bool				ats_enabled;
>  	bool				sva_enabled;
>  	struct list_head		bonds;
> 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 7edce914c45e..d148bb6d4289 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -909,8 +909,8 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
>  
>  	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>  	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
> -		for (i = 0; i < master->num_sids; i++) {
> -			cmd.cfgi.sid = master->sids[i];
> +		for (i = 0; i < master->num_streams; i++) {
> +			cmd.cfgi.sid = master->streams[i].id;
>  			arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
>  		}
>  	}
> @@ -1355,6 +1355,28 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
>  	return 0;
>  }
>  
> +/* smmu->streams_mutex must be held */
> +__maybe_unused
> +static struct arm_smmu_master *
> +arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> +{
> +	struct rb_node *node;
> +	struct arm_smmu_stream *stream;
> +
> +	node = smmu->streams.rb_node;
> +	while (node) {
> +		stream = rb_entry(node, struct arm_smmu_stream, node);
> +		if (stream->id < sid)
> +			node = node->rb_right;
> +		else if (stream->id > sid)
> +			node = node->rb_left;
> +		else
> +			return stream->master;
> +	}
> +
> +	return NULL;
> +}
> +
>  /* IRQ and event handlers */
>  static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>  {
> @@ -1588,8 +1610,8 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
>  
>  	arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
>  
> -	for (i = 0; i < master->num_sids; i++) {
> -		cmd.atc.sid = master->sids[i];
> +	for (i = 0; i < master->num_streams; i++) {
> +		cmd.atc.sid = master->streams[i].id;
>  		arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
>  	}
>  
> @@ -1632,8 +1654,8 @@ int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,
>  		if (!master->ats_enabled)
>  			continue;
>  
> -		for (i = 0; i < master->num_sids; i++) {
> -			cmd.atc.sid = master->sids[i];
> +		for (i = 0; i < master->num_streams; i++) {
> +			cmd.atc.sid = master->streams[i].id;
>  			arm_smmu_cmdq_batch_add(smmu_domain->smmu, &cmds, &cmd);
>  		}
>  	}
> @@ -2065,13 +2087,13 @@ static void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master)
>  	int i, j;
>  	struct arm_smmu_device *smmu = master->smmu;
>  
> -	for (i = 0; i < master->num_sids; ++i) {
> -		u32 sid = master->sids[i];
> +	for (i = 0; i < master->num_streams; ++i) {
> +		u32 sid = master->streams[i].id;
>  		__le64 *step = arm_smmu_get_step_for_sid(smmu, sid);
>  
>  		/* Bridged PCI devices may end up with duplicated IDs */
>  		for (j = 0; j < i; j++)
> -			if (master->sids[j] == sid)
> +			if (master->streams[j].id == sid)
>  				break;
>  		if (j < i)
>  			continue;
> @@ -2345,11 +2367,101 @@ static bool arm_smmu_sid_in_range(struct arm_smmu_device *smmu, u32 sid)
>  	return sid < limit;
>  }
>  
> +static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
> +				  struct arm_smmu_master *master)
> +{
> +	int i;
> +	int ret = 0;
> +	struct arm_smmu_stream *new_stream, *cur_stream;
> +	struct rb_node **new_node, *parent_node = NULL;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
> +
> +	master->streams = kcalloc(fwspec->num_ids, sizeof(*master->streams),
> +				  GFP_KERNEL);
> +	if (!master->streams)
> +		return -ENOMEM;
> +	master->num_streams = fwspec->num_ids;
> +
> +	mutex_lock(&smmu->streams_mutex);
> +	for (i = 0; i < fwspec->num_ids; i++) {
> +		u32 sid = fwspec->ids[i];
> +
> +		new_stream = &master->streams[i];
> +		new_stream->id = sid;
> +		new_stream->master = master;
> +
> +		/*
> +		 * Check the SIDs are in range of the SMMU and our stream table
> +		 */
> +		if (!arm_smmu_sid_in_range(smmu, sid)) {
> +			ret = -ERANGE;
> +			break;
> +		}
> +
> +		/* Ensure l2 strtab is initialised */
> +		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
> +			ret = arm_smmu_init_l2_strtab(smmu, sid);
> +			if (ret)
> +				break;
> +		}
> +
> +		/* Insert into SID tree */
> +		new_node = &(smmu->streams.rb_node);
> +		while (*new_node) {
> +			cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
> +					      node);
> +			parent_node = *new_node;
> +			if (cur_stream->id > new_stream->id) {
> +				new_node = &((*new_node)->rb_left);
> +			} else if (cur_stream->id < new_stream->id) {
> +				new_node = &((*new_node)->rb_right);
> +			} else {
> +				dev_warn(master->dev,
> +					 "stream %u already in tree\n",
> +					 cur_stream->id);
> +				ret = -EINVAL;
> +				break;
> +			}
> +		}
> +		if (ret)
> +			break;
> +
> +		rb_link_node(&new_stream->node, parent_node, new_node);
> +		rb_insert_color(&new_stream->node, &smmu->streams);
> +	}
> +
> +	if (ret) {
> +		for (i--; i >= 0; i--)
> +			rb_erase(&master->streams[i].node, &smmu->streams);
> +		kfree(master->streams);
> +	}
> +	mutex_unlock(&smmu->streams_mutex);
> +
> +	return ret;
> +}
> +
> +static void arm_smmu_remove_master(struct arm_smmu_master *master)
> +{
> +	int i;
> +	struct arm_smmu_device *smmu = master->smmu;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
> +
> +	if (!smmu || !master->streams)
> +		return;
> +
> +	mutex_lock(&smmu->streams_mutex);
> +	for (i = 0; i < fwspec->num_ids; i++)
> +		rb_erase(&master->streams[i].node, &smmu->streams);
> +	mutex_unlock(&smmu->streams_mutex);
> +
> +	kfree(master->streams);
> +}
> +
>  static struct iommu_ops arm_smmu_ops;
>  
>  static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>  {
> -	int i, ret;
> +	int ret;
>  	struct arm_smmu_device *smmu;
>  	struct arm_smmu_master *master;
>  	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> @@ -2370,27 +2482,12 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>  
>  	master->dev = dev;
>  	master->smmu = smmu;
> -	master->sids = fwspec->ids;
> -	master->num_sids = fwspec->num_ids;
>  	INIT_LIST_HEAD(&master->bonds);
>  	dev_iommu_priv_set(dev, master);
>  
> -	/* Check the SIDs are in range of the SMMU and our stream table */
> -	for (i = 0; i < master->num_sids; i++) {
> -		u32 sid = master->sids[i];
> -
> -		if (!arm_smmu_sid_in_range(smmu, sid)) {
> -			ret = -ERANGE;
> -			goto err_free_master;
> -		}
> -
> -		/* Ensure l2 strtab is initialised */
> -		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
> -			ret = arm_smmu_init_l2_strtab(smmu, sid);
> -			if (ret)
> -				goto err_free_master;
> -		}
> -	}
> +	ret = arm_smmu_insert_master(smmu, master);
> +	if (ret)
> +		goto err_free_master;
>  
>  	device_property_read_u32(dev, "pasid-num-bits", &master->ssid_bits);
>  	master->ssid_bits = min(smmu->ssid_bits, master->ssid_bits);
> @@ -2429,6 +2526,7 @@ static void arm_smmu_release_device(struct device *dev)
>  	WARN_ON(arm_smmu_master_sva_enabled(master));
>  	arm_smmu_detach_dev(master);
>  	arm_smmu_disable_pasid(master);
> +	arm_smmu_remove_master(master);
>  	kfree(master);
>  	iommu_fwspec_free(dev);
>  }
> @@ -2852,6 +2950,9 @@ static int arm_smmu_init_structures(struct arm_smmu_device *smmu)
>  {
>  	int ret;
>  
> +	mutex_init(&smmu->streams_mutex);
> +	smmu->streams = RB_ROOT;
> +
>  	ret = arm_smmu_init_queues(smmu);
>  	if (ret)
>  		return ret;
> 
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Re: [PATCH v13 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure

[Will Deacon]

On Tue, Mar 02, 2021 at 10:26:43AM +0100, Jean-Philippe Brucker wrote:
> When handling faults from the event or PRI queue, we need to find the
> struct device associated with a SID. Add a rb_tree to keep track of
> SIDs.
> 
> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  13 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 157 ++++++++++++++++----
>  2 files changed, 140 insertions(+), 30 deletions(-)
> 
> 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 f985817c967a..7b15b7580c6e 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -639,6 +639,15 @@ struct arm_smmu_device {
>  
>  	/* IOMMU core code handle */
>  	struct iommu_device		iommu;
> +
> +	struct rb_root			streams;
> +	struct mutex			streams_mutex;
> +};
> +
> +struct arm_smmu_stream {
> +	u32				id;
> +	struct arm_smmu_master		*master;
> +	struct rb_node			node;
>  };
>  
>  /* SMMU private data for each master */
> @@ -647,8 +656,8 @@ struct arm_smmu_master {
>  	struct device			*dev;
>  	struct arm_smmu_domain		*domain;
>  	struct list_head		domain_head;
> -	u32				*sids;
> -	unsigned int			num_sids;
> +	struct arm_smmu_stream		*streams;
> +	unsigned int			num_streams;
>  	bool				ats_enabled;
>  	bool				sva_enabled;
>  	struct list_head		bonds;
> 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 7edce914c45e..d148bb6d4289 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -909,8 +909,8 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
>  
>  	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
>  	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
> -		for (i = 0; i < master->num_sids; i++) {
> -			cmd.cfgi.sid = master->sids[i];
> +		for (i = 0; i < master->num_streams; i++) {
> +			cmd.cfgi.sid = master->streams[i].id;
>  			arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
>  		}
>  	}
> @@ -1355,6 +1355,28 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
>  	return 0;
>  }
>  
> +/* smmu->streams_mutex must be held */

Can you add a lockdep assertion for that?

> +__maybe_unused
> +static struct arm_smmu_master *
> +arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> +{
> +	struct rb_node *node;
> +	struct arm_smmu_stream *stream;
> +
> +	node = smmu->streams.rb_node;
> +	while (node) {
> +		stream = rb_entry(node, struct arm_smmu_stream, node);
> +		if (stream->id < sid)
> +			node = node->rb_right;
> +		else if (stream->id > sid)
> +			node = node->rb_left;
> +		else
> +			return stream->master;
> +	}
> +
> +	return NULL;
> +}

[...]

> +static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
> +				  struct arm_smmu_master *master)
> +{
> +	int i;
> +	int ret = 0;
> +	struct arm_smmu_stream *new_stream, *cur_stream;
> +	struct rb_node **new_node, *parent_node = NULL;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
> +
> +	master->streams = kcalloc(fwspec->num_ids, sizeof(*master->streams),
> +				  GFP_KERNEL);
> +	if (!master->streams)
> +		return -ENOMEM;
> +	master->num_streams = fwspec->num_ids;
> +
> +	mutex_lock(&smmu->streams_mutex);
> +	for (i = 0; i < fwspec->num_ids; i++) {
> +		u32 sid = fwspec->ids[i];
> +
> +		new_stream = &master->streams[i];
> +		new_stream->id = sid;
> +		new_stream->master = master;
> +
> +		/*
> +		 * Check the SIDs are in range of the SMMU and our stream table
> +		 */
> +		if (!arm_smmu_sid_in_range(smmu, sid)) {
> +			ret = -ERANGE;
> +			break;
> +		}
> +
> +		/* Ensure l2 strtab is initialised */
> +		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
> +			ret = arm_smmu_init_l2_strtab(smmu, sid);
> +			if (ret)
> +				break;
> +		}
> +
> +		/* Insert into SID tree */
> +		new_node = &(smmu->streams.rb_node);
> +		while (*new_node) {
> +			cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
> +					      node);
> +			parent_node = *new_node;
> +			if (cur_stream->id > new_stream->id) {
> +				new_node = &((*new_node)->rb_left);
> +			} else if (cur_stream->id < new_stream->id) {
> +				new_node = &((*new_node)->rb_right);
> +			} else {
> +				dev_warn(master->dev,
> +					 "stream %u already in tree\n",
> +					 cur_stream->id);
> +				ret = -EINVAL;
> +				break;
> +			}
> +		}
> +		if (ret)
> +			break;
> +
> +		rb_link_node(&new_stream->node, parent_node, new_node);
> +		rb_insert_color(&new_stream->node, &smmu->streams);
> +	}
> +
> +	if (ret) {
> +		for (i--; i >= 0; i--)

Is 'i--' really what you want for the initial value? Doesn't that correspond
to the ID you *didn't* add to the tree?

> +			rb_erase(&master->streams[i].node, &smmu->streams);
> +		kfree(master->streams);

Do you need to NULLify master->streams and/or reset master->num_streams
after this? Seems like they're left dangling.

Will
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Re: [PATCH v13 07/10] iommu/arm-smmu-v3: Maintain a SID->device structure

[Jean-Philippe Brucker]

On Thu, Mar 25, 2021 at 05:48:07PM +0000, Will Deacon wrote:
> > +/* smmu->streams_mutex must be held */
> 
> Can you add a lockdep assertion for that?

Sure

> > +__maybe_unused
> > +static struct arm_smmu_master *
> > +arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> > +{
> > +	struct rb_node *node;
> > +	struct arm_smmu_stream *stream;
> > +
> > +	node = smmu->streams.rb_node;
> > +	while (node) {
> > +		stream = rb_entry(node, struct arm_smmu_stream, node);
> > +		if (stream->id < sid)
> > +			node = node->rb_right;
> > +		else if (stream->id > sid)
> > +			node = node->rb_left;
> > +		else
> > +			return stream->master;
> > +	}
> > +
> > +	return NULL;
> > +}
> 
> [...]
> 
> > +static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
> > +				  struct arm_smmu_master *master)
> > +{
> > +	int i;
> > +	int ret = 0;
> > +	struct arm_smmu_stream *new_stream, *cur_stream;
> > +	struct rb_node **new_node, *parent_node = NULL;
> > +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
> > +
> > +	master->streams = kcalloc(fwspec->num_ids, sizeof(*master->streams),
> > +				  GFP_KERNEL);
> > +	if (!master->streams)
> > +		return -ENOMEM;
> > +	master->num_streams = fwspec->num_ids;
> > +
> > +	mutex_lock(&smmu->streams_mutex);
> > +	for (i = 0; i < fwspec->num_ids; i++) {
> > +		u32 sid = fwspec->ids[i];
> > +
> > +		new_stream = &master->streams[i];
> > +		new_stream->id = sid;
> > +		new_stream->master = master;
> > +
> > +		/*
> > +		 * Check the SIDs are in range of the SMMU and our stream table
> > +		 */
> > +		if (!arm_smmu_sid_in_range(smmu, sid)) {
> > +			ret = -ERANGE;
> > +			break;
> > +		}
> > +
> > +		/* Ensure l2 strtab is initialised */
> > +		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
> > +			ret = arm_smmu_init_l2_strtab(smmu, sid);
> > +			if (ret)
> > +				break;
> > +		}
> > +
> > +		/* Insert into SID tree */
> > +		new_node = &(smmu->streams.rb_node);
> > +		while (*new_node) {
> > +			cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
> > +					      node);
> > +			parent_node = *new_node;
> > +			if (cur_stream->id > new_stream->id) {
> > +				new_node = &((*new_node)->rb_left);
> > +			} else if (cur_stream->id < new_stream->id) {
> > +				new_node = &((*new_node)->rb_right);
> > +			} else {
> > +				dev_warn(master->dev,
> > +					 "stream %u already in tree\n",
> > +					 cur_stream->id);
> > +				ret = -EINVAL;
> > +				break;
> > +			}
> > +		}
> > +		if (ret)
> > +			break;
> > +
> > +		rb_link_node(&new_stream->node, parent_node, new_node);
> > +		rb_insert_color(&new_stream->node, &smmu->streams);
> > +	}
> > +
> > +	if (ret) {
> > +		for (i--; i >= 0; i--)
> 
> Is 'i--' really what you want for the initial value? Doesn't that correspond
> to the ID you *didn't* add to the tree?

In case of error we break out of the loop, with i corresponding to the
stream that caused a fault but wasn't yet added to the tree. So i-- is
the last stream that was successfully added, or -1 in which case we don't
enter this for loop.

> > +			rb_erase(&master->streams[i].node, &smmu->streams);
> > +		kfree(master->streams);
> 
> Do you need to NULLify master->streams and/or reset master->num_streams
> after this? Seems like they're left dangling.

master is freed by arm_smmu_probe_device() when we return an error. Since
this function is unlikely to ever have another caller I didn't bother
cleaning up here

Thanks,
Jean
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[PATCH v13 08/10] dt-bindings: document stall property for IOMMU masters

[Jean-Philippe Brucker]

On ARM systems, some platform devices behind an IOMMU may support stall,
which is the ability to recover from page faults. Let the firmware tell us
when a device supports stall.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 .../devicetree/bindings/iommu/iommu.txt        | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/iommu/iommu.txt b/Documentation/devicetree/bindings/iommu/iommu.txt
index 3c36334e4f94..26ba9e530f13 100644
--- a/Documentation/devicetree/bindings/iommu/iommu.txt
+++ b/Documentation/devicetree/bindings/iommu/iommu.txt
@@ -92,6 +92,24 @@ Optional properties:
   tagging DMA transactions with an address space identifier. By default,
   this is 0, which means that the device only has one address space.
 
+- dma-can-stall: When present, the master can wait for a transaction to
+  complete for an indefinite amount of time. Upon translation fault some
+  IOMMUs, instead of aborting the translation immediately, may first
+  notify the driver and keep the transaction in flight. This allows the OS
+  to inspect the fault and, for example, make physical pages resident
+  before updating the mappings and completing the transaction. Such IOMMU
+  accepts a limited number of simultaneous stalled transactions before
+  having to either put back-pressure on the master, or abort new faulting
+  transactions.
+
+  Firmware has to opt-in stalling, because most buses and masters don't
+  support it. In particular it isn't compatible with PCI, where
+  transactions have to complete before a time limit. More generally it
+  won't work in systems and masters that haven't been designed for
+  stalling. For example the OS, in order to handle a stalled transaction,
+  may attempt to retrieve pages from secondary storage in a stalled
+  domain, leading to a deadlock.
+
 
 Notes:
 ======
-- 
2.30.1

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[PATCH v13 09/10] ACPI/IORT: Enable stall support for platform devices

[Jean-Philippe Brucker]

Copy the "Stall supported" bit, that tells whether a named component
supports stall, into the dma-can-stall device property.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/acpi/arm64/iort.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 3912a1f6058e..0828f70cb782 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -968,13 +968,15 @@ static int iort_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 static void iort_named_component_init(struct device *dev,
 				      struct acpi_iort_node *node)
 {
-	struct property_entry props[2] = {};
+	struct property_entry props[3] = {};
 	struct acpi_iort_named_component *nc;
 
 	nc = (struct acpi_iort_named_component *)node->node_data;
 	props[0] = PROPERTY_ENTRY_U32("pasid-num-bits",
 				      FIELD_GET(ACPI_IORT_NC_PASID_BITS,
 						nc->node_flags));
+	if (nc->node_flags & ACPI_IORT_NC_STALL_SUPPORTED)
+		props[1] = PROPERTY_ENTRY_BOOL("dma-can-stall");
 
 	if (device_add_properties(dev, props))
 		dev_warn(dev, "Could not add device properties\n");
-- 
2.30.1

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[PATCH v13 10/10] iommu/arm-smmu-v3: Add stall support for platform devices

[Jean-Philippe Brucker]

The SMMU provides a Stall model for handling page faults in platform
devices. It is similar to PCIe PRI, but doesn't require devices to have
their own translation cache. Instead, faulting transactions are parked
and the OS is given a chance to fix the page tables and retry the
transaction.

Enable stall for devices that support it (opt-in by firmware). When an
event corresponds to a translation error, call the IOMMU fault handler.
If the fault is recoverable, it will call us back to terminate or
continue the stall.

To use stall device drivers need to enable IOMMU_DEV_FEAT_IOPF, which
initializes the fault queue for the device.

Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  43 ++++
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  59 +++++-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 196 +++++++++++++++++-
 3 files changed, 283 insertions(+), 15 deletions(-)

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 7b15b7580c6e..59af0bbd2f7b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -354,6 +354,13 @@
 #define CMDQ_PRI_1_GRPID		GENMASK_ULL(8, 0)
 #define CMDQ_PRI_1_RESP			GENMASK_ULL(13, 12)
 
+#define CMDQ_RESUME_0_RESP_TERM		0UL
+#define CMDQ_RESUME_0_RESP_RETRY	1UL
+#define CMDQ_RESUME_0_RESP_ABORT	2UL
+#define CMDQ_RESUME_0_RESP		GENMASK_ULL(13, 12)
+#define CMDQ_RESUME_0_SID		GENMASK_ULL(63, 32)
+#define CMDQ_RESUME_1_STAG		GENMASK_ULL(15, 0)
+
 #define CMDQ_SYNC_0_CS			GENMASK_ULL(13, 12)
 #define CMDQ_SYNC_0_CS_NONE		0
 #define CMDQ_SYNC_0_CS_IRQ		1
@@ -370,6 +377,25 @@
 
 #define EVTQ_0_ID			GENMASK_ULL(7, 0)
 
+#define EVT_ID_TRANSLATION_FAULT	0x10
+#define EVT_ID_ADDR_SIZE_FAULT		0x11
+#define EVT_ID_ACCESS_FAULT		0x12
+#define EVT_ID_PERMISSION_FAULT		0x13
+
+#define EVTQ_0_SSV			(1UL << 11)
+#define EVTQ_0_SSID			GENMASK_ULL(31, 12)
+#define EVTQ_0_SID			GENMASK_ULL(63, 32)
+#define EVTQ_1_STAG			GENMASK_ULL(15, 0)
+#define EVTQ_1_STALL			(1UL << 31)
+#define EVTQ_1_PnU			(1UL << 33)
+#define EVTQ_1_InD			(1UL << 34)
+#define EVTQ_1_RnW			(1UL << 35)
+#define EVTQ_1_S2			(1UL << 39)
+#define EVTQ_1_CLASS			GENMASK_ULL(41, 40)
+#define EVTQ_1_TT_READ			(1UL << 44)
+#define EVTQ_2_ADDR			GENMASK_ULL(63, 0)
+#define EVTQ_3_IPA			GENMASK_ULL(51, 12)
+
 /* PRI queue */
 #define PRIQ_ENT_SZ_SHIFT		4
 #define PRIQ_ENT_DWORDS			((1 << PRIQ_ENT_SZ_SHIFT) >> 3)
@@ -464,6 +490,13 @@ struct arm_smmu_cmdq_ent {
 			enum pri_resp		resp;
 		} pri;
 
+		#define CMDQ_OP_RESUME		0x44
+		struct {
+			u32			sid;
+			u16			stag;
+			u8			resp;
+		} resume;
+
 		#define CMDQ_OP_CMD_SYNC	0x46
 		struct {
 			u64			msiaddr;
@@ -522,6 +555,7 @@ struct arm_smmu_cmdq_batch {
 
 struct arm_smmu_evtq {
 	struct arm_smmu_queue		q;
+	struct iopf_queue		*iopf;
 	u32				max_stalls;
 };
 
@@ -659,7 +693,9 @@ struct arm_smmu_master {
 	struct arm_smmu_stream		*streams;
 	unsigned int			num_streams;
 	bool				ats_enabled;
+	bool				stall_enabled;
 	bool				sva_enabled;
+	bool				iopf_enabled;
 	struct list_head		bonds;
 	unsigned int			ssid_bits;
 };
@@ -678,6 +714,7 @@ struct arm_smmu_domain {
 
 	struct io_pgtable_ops		*pgtbl_ops;
 	bool				non_strict;
+	bool				stall_enabled;
 	atomic_t			nr_ats_masters;
 
 	enum arm_smmu_domain_stage	stage;
@@ -719,6 +756,7 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
 bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
 int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
 int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
+bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master);
 struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
 				    void *drvdata);
 void arm_smmu_sva_unbind(struct iommu_sva *handle);
@@ -750,6 +788,11 @@ static inline int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
 	return -ENODEV;
 }
 
+static inline bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
+{
+	return false;
+}
+
 static inline struct iommu_sva *
 arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
 {
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index bb251cab61f3..ee66d1f4cb81 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -435,9 +435,13 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
 	return true;
 }
 
-static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
+bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
 {
-	return false;
+	/* We're not keeping track of SIDs in fault events */
+	if (master->num_streams != 1)
+		return false;
+
+	return master->stall_enabled;
 }
 
 bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
@@ -445,8 +449,8 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
 	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
 		return false;
 
-	/* SSID and IOPF support are mandatory for the moment */
-	return master->ssid_bits && arm_smmu_iopf_supported(master);
+	/* SSID support is mandatory for the moment */
+	return master->ssid_bits;
 }
 
 bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
@@ -459,13 +463,55 @@ bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
 	return enabled;
 }
 
+static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master *master)
+{
+	int ret;
+	struct device *dev = master->dev;
+
+	/*
+	 * Drivers for devices supporting PRI or stall should enable IOPF first.
+	 * Others have device-specific fault handlers and don't need IOPF.
+	 */
+	if (!arm_smmu_master_iopf_supported(master))
+		return 0;
+
+	if (!master->iopf_enabled)
+		return -EINVAL;
+
+	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
+	if (ret)
+		return ret;
+
+	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
+	if (ret) {
+		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
+		return ret;
+	}
+	return 0;
+}
+
+static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master)
+{
+	struct device *dev = master->dev;
+
+	if (!master->iopf_enabled)
+		return;
+
+	iommu_unregister_device_fault_handler(dev);
+	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
+}
+
 int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
 {
+	int ret;
+
 	mutex_lock(&sva_lock);
-	master->sva_enabled = true;
+	ret = arm_smmu_master_sva_enable_iopf(master);
+	if (!ret)
+		master->sva_enabled = true;
 	mutex_unlock(&sva_lock);
 
-	return 0;
+	return ret;
 }
 
 int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
@@ -476,6 +522,7 @@ int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
 		mutex_unlock(&sva_lock);
 		return -EBUSY;
 	}
+	arm_smmu_master_sva_disable_iopf(master);
 	master->sva_enabled = false;
 	mutex_unlock(&sva_lock);
 
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 d148bb6d4289..363744df8d51 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -32,6 +32,7 @@
 #include <linux/amba/bus.h>
 
 #include "arm-smmu-v3.h"
+#include "../../iommu-sva-lib.h"
 
 static bool disable_bypass = true;
 module_param(disable_bypass, bool, 0444);
@@ -315,6 +316,11 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
 		}
 		cmd[1] |= FIELD_PREP(CMDQ_PRI_1_RESP, ent->pri.resp);
 		break;
+	case CMDQ_OP_RESUME:
+		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_SID, ent->resume.sid);
+		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_RESP, ent->resume.resp);
+		cmd[1] |= FIELD_PREP(CMDQ_RESUME_1_STAG, ent->resume.stag);
+		break;
 	case CMDQ_OP_CMD_SYNC:
 		if (ent->sync.msiaddr) {
 			cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_CS, CMDQ_SYNC_0_CS_IRQ);
@@ -878,6 +884,44 @@ static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
 	return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
 }
 
+static int arm_smmu_page_response(struct device *dev,
+				  struct iommu_fault_event *unused,
+				  struct iommu_page_response *resp)
+{
+	struct arm_smmu_cmdq_ent cmd = {0};
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	int sid = master->streams[0].id;
+
+	if (master->stall_enabled) {
+		cmd.opcode		= CMDQ_OP_RESUME;
+		cmd.resume.sid		= sid;
+		cmd.resume.stag		= resp->grpid;
+		switch (resp->code) {
+		case IOMMU_PAGE_RESP_INVALID:
+		case IOMMU_PAGE_RESP_FAILURE:
+			cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
+			break;
+		case IOMMU_PAGE_RESP_SUCCESS:
+			cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
+			break;
+		default:
+			return -EINVAL;
+		}
+	} else {
+		return -ENODEV;
+	}
+
+	arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
+	/*
+	 * Don't send a SYNC, it doesn't do anything for RESUME or PRI_RESP.
+	 * RESUME consumption guarantees that the stalled transaction will be
+	 * terminated... at some point in the future. PRI_RESP is fire and
+	 * forget.
+	 */
+
+	return 0;
+}
+
 /* Context descriptor manipulation functions */
 void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid)
 {
@@ -988,7 +1032,6 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
 	u64 val;
 	bool cd_live;
 	__le64 *cdptr;
-	struct arm_smmu_device *smmu = smmu_domain->smmu;
 
 	if (WARN_ON(ssid >= (1 << smmu_domain->s1_cfg.s1cdmax)))
 		return -E2BIG;
@@ -1033,8 +1076,7 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
 			FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) |
 			CTXDESC_CD_0_V;
 
-		/* STALL_MODEL==0b10 && CD.S==0 is ILLEGAL */
-		if (smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
+		if (smmu_domain->stall_enabled)
 			val |= CTXDESC_CD_0_S;
 	}
 
@@ -1278,7 +1320,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
 			 FIELD_PREP(STRTAB_STE_1_STRW, strw));
 
 		if (smmu->features & ARM_SMMU_FEAT_STALLS &&
-		   !(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
+		    !master->stall_enabled)
 			dst[1] |= cpu_to_le64(STRTAB_STE_1_S1STALLD);
 
 		val |= (s1_cfg->cdcfg.cdtab_dma & STRTAB_STE_0_S1CTXPTR_MASK) |
@@ -1356,7 +1398,6 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
 }
 
 /* smmu->streams_mutex must be held */
-__maybe_unused
 static struct arm_smmu_master *
 arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
 {
@@ -1378,9 +1419,103 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
 }
 
 /* IRQ and event handlers */
+static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)
+{
+	int ret;
+	u32 reason;
+	u32 perm = 0;
+	struct arm_smmu_master *master;
+	bool ssid_valid = evt[0] & EVTQ_0_SSV;
+	u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
+	struct iommu_fault_event fault_evt = { };
+	struct iommu_fault *flt = &fault_evt.fault;
+
+	switch (FIELD_GET(EVTQ_0_ID, evt[0])) {
+	case EVT_ID_TRANSLATION_FAULT:
+		reason = IOMMU_FAULT_REASON_PTE_FETCH;
+		break;
+	case EVT_ID_ADDR_SIZE_FAULT:
+		reason = IOMMU_FAULT_REASON_OOR_ADDRESS;
+		break;
+	case EVT_ID_ACCESS_FAULT:
+		reason = IOMMU_FAULT_REASON_ACCESS;
+		break;
+	case EVT_ID_PERMISSION_FAULT:
+		reason = IOMMU_FAULT_REASON_PERMISSION;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	/* Stage-2 is always pinned at the moment */
+	if (evt[1] & EVTQ_1_S2)
+		return -EFAULT;
+
+	if (evt[1] & EVTQ_1_RnW)
+		perm |= IOMMU_FAULT_PERM_READ;
+	else
+		perm |= IOMMU_FAULT_PERM_WRITE;
+
+	if (evt[1] & EVTQ_1_InD)
+		perm |= IOMMU_FAULT_PERM_EXEC;
+
+	if (evt[1] & EVTQ_1_PnU)
+		perm |= IOMMU_FAULT_PERM_PRIV;
+
+	if (evt[1] & EVTQ_1_STALL) {
+		flt->type = IOMMU_FAULT_PAGE_REQ;
+		flt->prm = (struct iommu_fault_page_request) {
+			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
+			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
+			.perm = perm,
+			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
+		};
+
+		if (ssid_valid) {
+			flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
+			flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
+		}
+	} else {
+		flt->type = IOMMU_FAULT_DMA_UNRECOV;
+		flt->event = (struct iommu_fault_unrecoverable) {
+			.reason = reason,
+			.flags = IOMMU_FAULT_UNRECOV_ADDR_VALID,
+			.perm = perm,
+			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
+		};
+
+		if (ssid_valid) {
+			flt->event.flags |= IOMMU_FAULT_UNRECOV_PASID_VALID;
+			flt->event.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
+		}
+	}
+
+	mutex_lock(&smmu->streams_mutex);
+	master = arm_smmu_find_master(smmu, sid);
+	if (!master) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	ret = iommu_report_device_fault(master->dev, &fault_evt);
+	if (ret && flt->type == IOMMU_FAULT_PAGE_REQ) {
+		/* Nobody cared, abort the access */
+		struct iommu_page_response resp = {
+			.pasid		= flt->prm.pasid,
+			.grpid		= flt->prm.grpid,
+			.code		= IOMMU_PAGE_RESP_FAILURE,
+		};
+		arm_smmu_page_response(master->dev, &fault_evt, &resp);
+	}
+
+out_unlock:
+	mutex_unlock(&smmu->streams_mutex);
+	return ret;
+}
+
 static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
 {
-	int i;
+	int i, ret;
 	struct arm_smmu_device *smmu = dev;
 	struct arm_smmu_queue *q = &smmu->evtq.q;
 	struct arm_smmu_ll_queue *llq = &q->llq;
@@ -1390,6 +1525,10 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
 		while (!queue_remove_raw(q, evt)) {
 			u8 id = FIELD_GET(EVTQ_0_ID, evt[0]);
 
+			ret = arm_smmu_handle_evt(smmu, evt);
+			if (!ret)
+				continue;
+
 			dev_info(smmu->dev, "event 0x%02x received:\n", id);
 			for (i = 0; i < ARRAY_SIZE(evt); ++i)
 				dev_info(smmu->dev, "\t0x%016llx\n",
@@ -1924,6 +2063,8 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 
 	cfg->s1cdmax = master->ssid_bits;
 
+	smmu_domain->stall_enabled = master->stall_enabled;
+
 	ret = arm_smmu_alloc_cd_tables(smmu_domain);
 	if (ret)
 		goto out_free_asid;
@@ -2271,6 +2412,12 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 			smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
 		ret = -EINVAL;
 		goto out_unlock;
+	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
+		   smmu_domain->stall_enabled != master->stall_enabled) {
+		dev_err(dev, "cannot attach to stall-%s domain\n",
+			smmu_domain->stall_enabled ? "enabled" : "disabled");
+		ret = -EINVAL;
+		goto out_unlock;
 	}
 
 	master->domain = smmu_domain;
@@ -2506,6 +2653,11 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 		master->ssid_bits = min_t(u8, master->ssid_bits,
 					  CTXDESC_LINEAR_CDMAX);
 
+	if ((smmu->features & ARM_SMMU_FEAT_STALLS &&
+	     device_property_read_bool(dev, "dma-can-stall")) ||
+	    smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
+		master->stall_enabled = true;
+
 	return &smmu->iommu;
 
 err_free_master:
@@ -2523,7 +2675,8 @@ static void arm_smmu_release_device(struct device *dev)
 		return;
 
 	master = dev_iommu_priv_get(dev);
-	WARN_ON(arm_smmu_master_sva_enabled(master));
+	if (WARN_ON(arm_smmu_master_sva_enabled(master)))
+		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
 	arm_smmu_detach_dev(master);
 	arm_smmu_disable_pasid(master);
 	arm_smmu_remove_master(master);
@@ -2651,6 +2804,8 @@ static bool arm_smmu_dev_has_feature(struct device *dev,
 		return false;
 
 	switch (feat) {
+	case IOMMU_DEV_FEAT_IOPF:
+		return arm_smmu_master_iopf_supported(master);
 	case IOMMU_DEV_FEAT_SVA:
 		return arm_smmu_master_sva_supported(master);
 	default:
@@ -2667,6 +2822,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
 		return false;
 
 	switch (feat) {
+	case IOMMU_DEV_FEAT_IOPF:
+		return master->iopf_enabled;
 	case IOMMU_DEV_FEAT_SVA:
 		return arm_smmu_master_sva_enabled(master);
 	default:
@@ -2677,6 +2834,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
 static int arm_smmu_dev_enable_feature(struct device *dev,
 				       enum iommu_dev_features feat)
 {
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
 	if (!arm_smmu_dev_has_feature(dev, feat))
 		return -ENODEV;
 
@@ -2684,8 +2843,11 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
 		return -EBUSY;
 
 	switch (feat) {
+	case IOMMU_DEV_FEAT_IOPF:
+		master->iopf_enabled = true;
+		return 0;
 	case IOMMU_DEV_FEAT_SVA:
-		return arm_smmu_master_enable_sva(dev_iommu_priv_get(dev));
+		return arm_smmu_master_enable_sva(master);
 	default:
 		return -EINVAL;
 	}
@@ -2694,12 +2856,19 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
 static int arm_smmu_dev_disable_feature(struct device *dev,
 					enum iommu_dev_features feat)
 {
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
 	if (!arm_smmu_dev_feature_enabled(dev, feat))
 		return -EINVAL;
 
 	switch (feat) {
+	case IOMMU_DEV_FEAT_IOPF:
+		if (master->sva_enabled)
+			return -EBUSY;
+		master->iopf_enabled = false;
+		return 0;
 	case IOMMU_DEV_FEAT_SVA:
-		return arm_smmu_master_disable_sva(dev_iommu_priv_get(dev));
+		return arm_smmu_master_disable_sva(master);
 	default:
 		return -EINVAL;
 	}
@@ -2730,6 +2899,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.sva_bind		= arm_smmu_sva_bind,
 	.sva_unbind		= arm_smmu_sva_unbind,
 	.sva_get_pasid		= arm_smmu_sva_get_pasid,
+	.page_response		= arm_smmu_page_response,
 	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 };
 
@@ -2827,6 +2997,13 @@ static int arm_smmu_init_queues(struct arm_smmu_device *smmu)
 	if (ret)
 		return ret;
 
+	if ((smmu->features & ARM_SMMU_FEAT_SVA) &&
+	    (smmu->features & ARM_SMMU_FEAT_STALLS)) {
+		smmu->evtq.iopf = iopf_queue_alloc(dev_name(smmu->dev));
+		if (!smmu->evtq.iopf)
+			return -ENOMEM;
+	}
+
 	/* priq */
 	if (!(smmu->features & ARM_SMMU_FEAT_PRI))
 		return 0;
@@ -3742,6 +3919,7 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
 	iommu_device_unregister(&smmu->iommu);
 	iommu_device_sysfs_remove(&smmu->iommu);
 	arm_smmu_device_disable(smmu);
+	iopf_queue_free(smmu->evtq.iopf);
 
 	return 0;
 }
-- 
2.30.1

_______________________________________________
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH v13 10/10] iommu/arm-smmu-v3: Add stall support for platform devices

[Auger Eric]

Hi Jean,

On 3/2/21 10:26 AM, Jean-Philippe Brucker wrote:
> The SMMU provides a Stall model for handling page faults in platform
> devices. It is similar to PCIe PRI, but doesn't require devices to have
> their own translation cache. Instead, faulting transactions are parked
> and the OS is given a chance to fix the page tables and retry the
> transaction.
> 
> Enable stall for devices that support it (opt-in by firmware). When an
> event corresponds to a translation error, call the IOMMU fault handler.
> If the fault is recoverable, it will call us back to terminate or
> continue the stall.
> 
> To use stall device drivers need to enable IOMMU_DEV_FEAT_IOPF, which
> initializes the fault queue for the device.
> 
> Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric

> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  43 ++++
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  59 +++++-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 196 +++++++++++++++++-
>  3 files changed, 283 insertions(+), 15 deletions(-)
> 
> 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 7b15b7580c6e..59af0bbd2f7b 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -354,6 +354,13 @@
>  #define CMDQ_PRI_1_GRPID		GENMASK_ULL(8, 0)
>  #define CMDQ_PRI_1_RESP			GENMASK_ULL(13, 12)
>  
> +#define CMDQ_RESUME_0_RESP_TERM		0UL
> +#define CMDQ_RESUME_0_RESP_RETRY	1UL
> +#define CMDQ_RESUME_0_RESP_ABORT	2UL
> +#define CMDQ_RESUME_0_RESP		GENMASK_ULL(13, 12)
> +#define CMDQ_RESUME_0_SID		GENMASK_ULL(63, 32)
> +#define CMDQ_RESUME_1_STAG		GENMASK_ULL(15, 0)
> +
>  #define CMDQ_SYNC_0_CS			GENMASK_ULL(13, 12)
>  #define CMDQ_SYNC_0_CS_NONE		0
>  #define CMDQ_SYNC_0_CS_IRQ		1
> @@ -370,6 +377,25 @@
>  
>  #define EVTQ_0_ID			GENMASK_ULL(7, 0)
>  
> +#define EVT_ID_TRANSLATION_FAULT	0x10
> +#define EVT_ID_ADDR_SIZE_FAULT		0x11
> +#define EVT_ID_ACCESS_FAULT		0x12
> +#define EVT_ID_PERMISSION_FAULT		0x13
> +
> +#define EVTQ_0_SSV			(1UL << 11)
> +#define EVTQ_0_SSID			GENMASK_ULL(31, 12)
> +#define EVTQ_0_SID			GENMASK_ULL(63, 32)
> +#define EVTQ_1_STAG			GENMASK_ULL(15, 0)
> +#define EVTQ_1_STALL			(1UL << 31)
> +#define EVTQ_1_PnU			(1UL << 33)
> +#define EVTQ_1_InD			(1UL << 34)
> +#define EVTQ_1_RnW			(1UL << 35)
> +#define EVTQ_1_S2			(1UL << 39)
> +#define EVTQ_1_CLASS			GENMASK_ULL(41, 40)
> +#define EVTQ_1_TT_READ			(1UL << 44)
> +#define EVTQ_2_ADDR			GENMASK_ULL(63, 0)
> +#define EVTQ_3_IPA			GENMASK_ULL(51, 12)
> +
>  /* PRI queue */
>  #define PRIQ_ENT_SZ_SHIFT		4
>  #define PRIQ_ENT_DWORDS			((1 << PRIQ_ENT_SZ_SHIFT) >> 3)
> @@ -464,6 +490,13 @@ struct arm_smmu_cmdq_ent {
>  			enum pri_resp		resp;
>  		} pri;
>  
> +		#define CMDQ_OP_RESUME		0x44
> +		struct {
> +			u32			sid;
> +			u16			stag;
> +			u8			resp;
> +		} resume;
> +
>  		#define CMDQ_OP_CMD_SYNC	0x46
>  		struct {
>  			u64			msiaddr;
> @@ -522,6 +555,7 @@ struct arm_smmu_cmdq_batch {
>  
>  struct arm_smmu_evtq {
>  	struct arm_smmu_queue		q;
> +	struct iopf_queue		*iopf;
>  	u32				max_stalls;
>  };
>  
> @@ -659,7 +693,9 @@ struct arm_smmu_master {
>  	struct arm_smmu_stream		*streams;
>  	unsigned int			num_streams;
>  	bool				ats_enabled;
> +	bool				stall_enabled;
>  	bool				sva_enabled;
> +	bool				iopf_enabled;
>  	struct list_head		bonds;
>  	unsigned int			ssid_bits;
>  };
> @@ -678,6 +714,7 @@ struct arm_smmu_domain {
>  
>  	struct io_pgtable_ops		*pgtbl_ops;
>  	bool				non_strict;
> +	bool				stall_enabled;
>  	atomic_t			nr_ats_masters;
>  
>  	enum arm_smmu_domain_stage	stage;
> @@ -719,6 +756,7 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
>  bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
>  int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
>  int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
> +bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master);
>  struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
>  				    void *drvdata);
>  void arm_smmu_sva_unbind(struct iommu_sva *handle);
> @@ -750,6 +788,11 @@ static inline int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
>  	return -ENODEV;
>  }
>  
> +static inline bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
> +{
> +	return false;
> +}
> +
>  static inline struct iommu_sva *
>  arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
>  {
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index bb251cab61f3..ee66d1f4cb81 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -435,9 +435,13 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
>  	return true;
>  }
>  
> -static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
> +bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
>  {
> -	return false;
> +	/* We're not keeping track of SIDs in fault events */
> +	if (master->num_streams != 1)
> +		return false;
> +
> +	return master->stall_enabled;
>  }
>  
>  bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
> @@ -445,8 +449,8 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
>  	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
>  		return false;
>  
> -	/* SSID and IOPF support are mandatory for the moment */
> -	return master->ssid_bits && arm_smmu_iopf_supported(master);
> +	/* SSID support is mandatory for the moment */
> +	return master->ssid_bits;
>  }
>  
>  bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
> @@ -459,13 +463,55 @@ bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
>  	return enabled;
>  }
>  
> +static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master *master)
> +{
> +	int ret;
> +	struct device *dev = master->dev;
> +
> +	/*
> +	 * Drivers for devices supporting PRI or stall should enable IOPF first.
> +	 * Others have device-specific fault handlers and don't need IOPF.
> +	 */
> +	if (!arm_smmu_master_iopf_supported(master))
> +		return 0;
> +
> +	if (!master->iopf_enabled)
> +		return -EINVAL;
> +
> +	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
> +	if (ret) {
> +		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master)
> +{
> +	struct device *dev = master->dev;
> +
> +	if (!master->iopf_enabled)
> +		return;
> +
> +	iommu_unregister_device_fault_handler(dev);
> +	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> +}
> +
>  int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
>  {
> +	int ret;
> +
>  	mutex_lock(&sva_lock);
> -	master->sva_enabled = true;
> +	ret = arm_smmu_master_sva_enable_iopf(master);
> +	if (!ret)
> +		master->sva_enabled = true;
>  	mutex_unlock(&sva_lock);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
> @@ -476,6 +522,7 @@ int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
>  		mutex_unlock(&sva_lock);
>  		return -EBUSY;
>  	}
> +	arm_smmu_master_sva_disable_iopf(master);
>  	master->sva_enabled = false;
>  	mutex_unlock(&sva_lock);
>  
> 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 d148bb6d4289..363744df8d51 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -32,6 +32,7 @@
>  #include <linux/amba/bus.h>
>  
>  #include "arm-smmu-v3.h"
> +#include "../../iommu-sva-lib.h"
>  
>  static bool disable_bypass = true;
>  module_param(disable_bypass, bool, 0444);
> @@ -315,6 +316,11 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
>  		}
>  		cmd[1] |= FIELD_PREP(CMDQ_PRI_1_RESP, ent->pri.resp);
>  		break;
> +	case CMDQ_OP_RESUME:
> +		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_SID, ent->resume.sid);
> +		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_RESP, ent->resume.resp);
> +		cmd[1] |= FIELD_PREP(CMDQ_RESUME_1_STAG, ent->resume.stag);
> +		break;
>  	case CMDQ_OP_CMD_SYNC:
>  		if (ent->sync.msiaddr) {
>  			cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_CS, CMDQ_SYNC_0_CS_IRQ);
> @@ -878,6 +884,44 @@ static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
>  	return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
>  }
>  
> +static int arm_smmu_page_response(struct device *dev,
> +				  struct iommu_fault_event *unused,
> +				  struct iommu_page_response *resp)
> +{
> +	struct arm_smmu_cmdq_ent cmd = {0};
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +	int sid = master->streams[0].id;
> +
> +	if (master->stall_enabled) {
> +		cmd.opcode		= CMDQ_OP_RESUME;
> +		cmd.resume.sid		= sid;
> +		cmd.resume.stag		= resp->grpid;
> +		switch (resp->code) {
> +		case IOMMU_PAGE_RESP_INVALID:
> +		case IOMMU_PAGE_RESP_FAILURE:
> +			cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
> +			break;
> +		case IOMMU_PAGE_RESP_SUCCESS:
> +			cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +	} else {
> +		return -ENODEV;
> +	}
> +
> +	arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
> +	/*
> +	 * Don't send a SYNC, it doesn't do anything for RESUME or PRI_RESP.
> +	 * RESUME consumption guarantees that the stalled transaction will be
> +	 * terminated... at some point in the future. PRI_RESP is fire and
> +	 * forget.
> +	 */
> +
> +	return 0;
> +}
> +
>  /* Context descriptor manipulation functions */
>  void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid)
>  {
> @@ -988,7 +1032,6 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
>  	u64 val;
>  	bool cd_live;
>  	__le64 *cdptr;
> -	struct arm_smmu_device *smmu = smmu_domain->smmu;
>  
>  	if (WARN_ON(ssid >= (1 << smmu_domain->s1_cfg.s1cdmax)))
>  		return -E2BIG;
> @@ -1033,8 +1076,7 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
>  			FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) |
>  			CTXDESC_CD_0_V;
>  
> -		/* STALL_MODEL==0b10 && CD.S==0 is ILLEGAL */
> -		if (smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
> +		if (smmu_domain->stall_enabled)
>  			val |= CTXDESC_CD_0_S;
>  	}
>  
> @@ -1278,7 +1320,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>  			 FIELD_PREP(STRTAB_STE_1_STRW, strw));
>  
>  		if (smmu->features & ARM_SMMU_FEAT_STALLS &&
> -		   !(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
> +		    !master->stall_enabled)
>  			dst[1] |= cpu_to_le64(STRTAB_STE_1_S1STALLD);
>  
>  		val |= (s1_cfg->cdcfg.cdtab_dma & STRTAB_STE_0_S1CTXPTR_MASK) |
> @@ -1356,7 +1398,6 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
>  }
>  
>  /* smmu->streams_mutex must be held */
> -__maybe_unused
>  static struct arm_smmu_master *
>  arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
>  {
> @@ -1378,9 +1419,103 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
>  }
>  
>  /* IRQ and event handlers */
> +static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)
> +{
> +	int ret;
> +	u32 reason;
> +	u32 perm = 0;
> +	struct arm_smmu_master *master;
> +	bool ssid_valid = evt[0] & EVTQ_0_SSV;
> +	u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
> +	struct iommu_fault_event fault_evt = { };
> +	struct iommu_fault *flt = &fault_evt.fault;
> +
> +	switch (FIELD_GET(EVTQ_0_ID, evt[0])) {
> +	case EVT_ID_TRANSLATION_FAULT:
> +		reason = IOMMU_FAULT_REASON_PTE_FETCH;
> +		break;
> +	case EVT_ID_ADDR_SIZE_FAULT:
> +		reason = IOMMU_FAULT_REASON_OOR_ADDRESS;
> +		break;
> +	case EVT_ID_ACCESS_FAULT:
> +		reason = IOMMU_FAULT_REASON_ACCESS;
> +		break;
> +	case EVT_ID_PERMISSION_FAULT:
> +		reason = IOMMU_FAULT_REASON_PERMISSION;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	/* Stage-2 is always pinned at the moment */
> +	if (evt[1] & EVTQ_1_S2)
> +		return -EFAULT;
> +
> +	if (evt[1] & EVTQ_1_RnW)
> +		perm |= IOMMU_FAULT_PERM_READ;
> +	else
> +		perm |= IOMMU_FAULT_PERM_WRITE;
> +
> +	if (evt[1] & EVTQ_1_InD)
> +		perm |= IOMMU_FAULT_PERM_EXEC;
> +
> +	if (evt[1] & EVTQ_1_PnU)
> +		perm |= IOMMU_FAULT_PERM_PRIV;
> +
> +	if (evt[1] & EVTQ_1_STALL) {
> +		flt->type = IOMMU_FAULT_PAGE_REQ;
> +		flt->prm = (struct iommu_fault_page_request) {
> +			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
> +			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
> +			.perm = perm,
> +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> +		};
> +
> +		if (ssid_valid) {
> +			flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
> +			flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
> +		}
> +	} else {
> +		flt->type = IOMMU_FAULT_DMA_UNRECOV;
> +		flt->event = (struct iommu_fault_unrecoverable) {
> +			.reason = reason,
> +			.flags = IOMMU_FAULT_UNRECOV_ADDR_VALID,
> +			.perm = perm,
> +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> +		};
> +
> +		if (ssid_valid) {
> +			flt->event.flags |= IOMMU_FAULT_UNRECOV_PASID_VALID;
> +			flt->event.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
> +		}
> +	}
> +
> +	mutex_lock(&smmu->streams_mutex);
> +	master = arm_smmu_find_master(smmu, sid);
> +	if (!master) {
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +
> +	ret = iommu_report_device_fault(master->dev, &fault_evt);
> +	if (ret && flt->type == IOMMU_FAULT_PAGE_REQ) {
> +		/* Nobody cared, abort the access */
> +		struct iommu_page_response resp = {
> +			.pasid		= flt->prm.pasid,
> +			.grpid		= flt->prm.grpid,
> +			.code		= IOMMU_PAGE_RESP_FAILURE,
> +		};
> +		arm_smmu_page_response(master->dev, &fault_evt, &resp);
> +	}
> +
> +out_unlock:
> +	mutex_unlock(&smmu->streams_mutex);
> +	return ret;
> +}
> +
>  static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>  {
> -	int i;
> +	int i, ret;
>  	struct arm_smmu_device *smmu = dev;
>  	struct arm_smmu_queue *q = &smmu->evtq.q;
>  	struct arm_smmu_ll_queue *llq = &q->llq;
> @@ -1390,6 +1525,10 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>  		while (!queue_remove_raw(q, evt)) {
>  			u8 id = FIELD_GET(EVTQ_0_ID, evt[0]);
>  
> +			ret = arm_smmu_handle_evt(smmu, evt);
> +			if (!ret)
> +				continue;
> +
>  			dev_info(smmu->dev, "event 0x%02x received:\n", id);
>  			for (i = 0; i < ARRAY_SIZE(evt); ++i)
>  				dev_info(smmu->dev, "\t0x%016llx\n",
> @@ -1924,6 +2063,8 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
>  
>  	cfg->s1cdmax = master->ssid_bits;
>  
> +	smmu_domain->stall_enabled = master->stall_enabled;
> +
>  	ret = arm_smmu_alloc_cd_tables(smmu_domain);
>  	if (ret)
>  		goto out_free_asid;
> @@ -2271,6 +2412,12 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
>  			smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
>  		ret = -EINVAL;
>  		goto out_unlock;
> +	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
> +		   smmu_domain->stall_enabled != master->stall_enabled) {
> +		dev_err(dev, "cannot attach to stall-%s domain\n",
> +			smmu_domain->stall_enabled ? "enabled" : "disabled");
> +		ret = -EINVAL;
> +		goto out_unlock;
>  	}
>  
>  	master->domain = smmu_domain;
> @@ -2506,6 +2653,11 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>  		master->ssid_bits = min_t(u8, master->ssid_bits,
>  					  CTXDESC_LINEAR_CDMAX);
>  
> +	if ((smmu->features & ARM_SMMU_FEAT_STALLS &&
> +	     device_property_read_bool(dev, "dma-can-stall")) ||
> +	    smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
> +		master->stall_enabled = true;
> +
>  	return &smmu->iommu;
>  
>  err_free_master:
> @@ -2523,7 +2675,8 @@ static void arm_smmu_release_device(struct device *dev)
>  		return;
>  
>  	master = dev_iommu_priv_get(dev);
> -	WARN_ON(arm_smmu_master_sva_enabled(master));
> +	if (WARN_ON(arm_smmu_master_sva_enabled(master)))
> +		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
>  	arm_smmu_detach_dev(master);
>  	arm_smmu_disable_pasid(master);
>  	arm_smmu_remove_master(master);
> @@ -2651,6 +2804,8 @@ static bool arm_smmu_dev_has_feature(struct device *dev,
>  		return false;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		return arm_smmu_master_iopf_supported(master);
>  	case IOMMU_DEV_FEAT_SVA:
>  		return arm_smmu_master_sva_supported(master);
>  	default:
> @@ -2667,6 +2822,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
>  		return false;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		return master->iopf_enabled;
>  	case IOMMU_DEV_FEAT_SVA:
>  		return arm_smmu_master_sva_enabled(master);
>  	default:
> @@ -2677,6 +2834,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
>  static int arm_smmu_dev_enable_feature(struct device *dev,
>  				       enum iommu_dev_features feat)
>  {
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +
>  	if (!arm_smmu_dev_has_feature(dev, feat))
>  		return -ENODEV;
>  
> @@ -2684,8 +2843,11 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
>  		return -EBUSY;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		master->iopf_enabled = true;
> +		return 0;
>  	case IOMMU_DEV_FEAT_SVA:
> -		return arm_smmu_master_enable_sva(dev_iommu_priv_get(dev));
> +		return arm_smmu_master_enable_sva(master);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -2694,12 +2856,19 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
>  static int arm_smmu_dev_disable_feature(struct device *dev,
>  					enum iommu_dev_features feat)
>  {
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +
>  	if (!arm_smmu_dev_feature_enabled(dev, feat))
>  		return -EINVAL;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		if (master->sva_enabled)
> +			return -EBUSY;
> +		master->iopf_enabled = false;
> +		return 0;
>  	case IOMMU_DEV_FEAT_SVA:
> -		return arm_smmu_master_disable_sva(dev_iommu_priv_get(dev));
> +		return arm_smmu_master_disable_sva(master);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -2730,6 +2899,7 @@ static struct iommu_ops arm_smmu_ops = {
>  	.sva_bind		= arm_smmu_sva_bind,
>  	.sva_unbind		= arm_smmu_sva_unbind,
>  	.sva_get_pasid		= arm_smmu_sva_get_pasid,
> +	.page_response		= arm_smmu_page_response,
>  	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
>  };
>  
> @@ -2827,6 +2997,13 @@ static int arm_smmu_init_queues(struct arm_smmu_device *smmu)
>  	if (ret)
>  		return ret;
>  
> +	if ((smmu->features & ARM_SMMU_FEAT_SVA) &&
> +	    (smmu->features & ARM_SMMU_FEAT_STALLS)) {
> +		smmu->evtq.iopf = iopf_queue_alloc(dev_name(smmu->dev));
> +		if (!smmu->evtq.iopf)
> +			return -ENOMEM;
> +	}
> +
>  	/* priq */
>  	if (!(smmu->features & ARM_SMMU_FEAT_PRI))
>  		return 0;
> @@ -3742,6 +3919,7 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
>  	iommu_device_unregister(&smmu->iommu);
>  	iommu_device_sysfs_remove(&smmu->iommu);
>  	arm_smmu_device_disable(smmu);
> +	iopf_queue_free(smmu->evtq.iopf);
>  
>  	return 0;
>  }
> 

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Re: [PATCH v13 10/10] iommu/arm-smmu-v3: Add stall support for platform devices

[Auger Eric]

Hi Jean,

On 3/2/21 10:26 AM, Jean-Philippe Brucker wrote:
> The SMMU provides a Stall model for handling page faults in platform
> devices. It is similar to PCIe PRI, but doesn't require devices to have
> their own translation cache. Instead, faulting transactions are parked
> and the OS is given a chance to fix the page tables and retry the
> transaction.
> 
> Enable stall for devices that support it (opt-in by firmware). When an
> event corresponds to a translation error, call the IOMMU fault handler.
> If the fault is recoverable, it will call us back to terminate or
> continue the stall.
> 
> To use stall device drivers need to enable IOMMU_DEV_FEAT_IOPF, which
> initializes the fault queue for the device.
> 
> Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  43 ++++
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  59 +++++-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 196 +++++++++++++++++-
>  3 files changed, 283 insertions(+), 15 deletions(-)
> 
> 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 7b15b7580c6e..59af0bbd2f7b 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -354,6 +354,13 @@
>  #define CMDQ_PRI_1_GRPID		GENMASK_ULL(8, 0)
>  #define CMDQ_PRI_1_RESP			GENMASK_ULL(13, 12)
>  
> +#define CMDQ_RESUME_0_RESP_TERM		0UL
> +#define CMDQ_RESUME_0_RESP_RETRY	1UL
> +#define CMDQ_RESUME_0_RESP_ABORT	2UL
> +#define CMDQ_RESUME_0_RESP		GENMASK_ULL(13, 12)
> +#define CMDQ_RESUME_0_SID		GENMASK_ULL(63, 32)
> +#define CMDQ_RESUME_1_STAG		GENMASK_ULL(15, 0)
> +
>  #define CMDQ_SYNC_0_CS			GENMASK_ULL(13, 12)
>  #define CMDQ_SYNC_0_CS_NONE		0
>  #define CMDQ_SYNC_0_CS_IRQ		1
> @@ -370,6 +377,25 @@
>  
>  #define EVTQ_0_ID			GENMASK_ULL(7, 0)
>  
> +#define EVT_ID_TRANSLATION_FAULT	0x10
> +#define EVT_ID_ADDR_SIZE_FAULT		0x11
> +#define EVT_ID_ACCESS_FAULT		0x12
> +#define EVT_ID_PERMISSION_FAULT		0x13
> +
> +#define EVTQ_0_SSV			(1UL << 11)
> +#define EVTQ_0_SSID			GENMASK_ULL(31, 12)
> +#define EVTQ_0_SID			GENMASK_ULL(63, 32)
> +#define EVTQ_1_STAG			GENMASK_ULL(15, 0)
> +#define EVTQ_1_STALL			(1UL << 31)
> +#define EVTQ_1_PnU			(1UL << 33)
> +#define EVTQ_1_InD			(1UL << 34)
> +#define EVTQ_1_RnW			(1UL << 35)
> +#define EVTQ_1_S2			(1UL << 39)
> +#define EVTQ_1_CLASS			GENMASK_ULL(41, 40)
> +#define EVTQ_1_TT_READ			(1UL << 44)
> +#define EVTQ_2_ADDR			GENMASK_ULL(63, 0)
> +#define EVTQ_3_IPA			GENMASK_ULL(51, 12)
> +
>  /* PRI queue */
>  #define PRIQ_ENT_SZ_SHIFT		4
>  #define PRIQ_ENT_DWORDS			((1 << PRIQ_ENT_SZ_SHIFT) >> 3)
> @@ -464,6 +490,13 @@ struct arm_smmu_cmdq_ent {
>  			enum pri_resp		resp;
>  		} pri;
>  
> +		#define CMDQ_OP_RESUME		0x44
> +		struct {
> +			u32			sid;
> +			u16			stag;
> +			u8			resp;
> +		} resume;
> +
>  		#define CMDQ_OP_CMD_SYNC	0x46
>  		struct {
>  			u64			msiaddr;
> @@ -522,6 +555,7 @@ struct arm_smmu_cmdq_batch {
>  
>  struct arm_smmu_evtq {
>  	struct arm_smmu_queue		q;
> +	struct iopf_queue		*iopf;
>  	u32				max_stalls;
>  };
>  
> @@ -659,7 +693,9 @@ struct arm_smmu_master {
>  	struct arm_smmu_stream		*streams;
>  	unsigned int			num_streams;
>  	bool				ats_enabled;
> +	bool				stall_enabled;
>  	bool				sva_enabled;
> +	bool				iopf_enabled;
>  	struct list_head		bonds;
>  	unsigned int			ssid_bits;
>  };
> @@ -678,6 +714,7 @@ struct arm_smmu_domain {
>  
>  	struct io_pgtable_ops		*pgtbl_ops;
>  	bool				non_strict;
> +	bool				stall_enabled;
>  	atomic_t			nr_ats_masters;
>  
>  	enum arm_smmu_domain_stage	stage;
> @@ -719,6 +756,7 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
>  bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
>  int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
>  int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
> +bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master);
>  struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
>  				    void *drvdata);
>  void arm_smmu_sva_unbind(struct iommu_sva *handle);
> @@ -750,6 +788,11 @@ static inline int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
>  	return -ENODEV;
>  }
>  
> +static inline bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
> +{
> +	return false;
> +}
> +
>  static inline struct iommu_sva *
>  arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
>  {
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index bb251cab61f3..ee66d1f4cb81 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -435,9 +435,13 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
>  	return true;
>  }
>  
> -static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
> +bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
>  {
> -	return false;
> +	/* We're not keeping track of SIDs in fault events */
> +	if (master->num_streams != 1)
> +		return false;
> +
> +	return master->stall_enabled;
>  }
>  
>  bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
> @@ -445,8 +449,8 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
>  	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
>  		return false;
>  
> -	/* SSID and IOPF support are mandatory for the moment */
> -	return master->ssid_bits && arm_smmu_iopf_supported(master);
> +	/* SSID support is mandatory for the moment */
> +	return master->ssid_bits;
>  }
>  
>  bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
> @@ -459,13 +463,55 @@ bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
>  	return enabled;
>  }
>  
> +static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master *master)
> +{
> +	int ret;
> +	struct device *dev = master->dev;
> +
> +	/*
> +	 * Drivers for devices supporting PRI or stall should enable IOPF first.
> +	 * Others have device-specific fault handlers and don't need IOPF.
> +	 */
> +	if (!arm_smmu_master_iopf_supported(master))
> +		return 0;
> +
> +	if (!master->iopf_enabled)
> +		return -EINVAL;
> +
> +	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
> +	if (ret) {
> +		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master)
> +{
> +	struct device *dev = master->dev;
> +
> +	if (!master->iopf_enabled)
> +		return;
> +
> +	iommu_unregister_device_fault_handler(dev);
> +	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> +}
> +
>  int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
>  {
> +	int ret;
> +
>  	mutex_lock(&sva_lock);
> -	master->sva_enabled = true;
> +	ret = arm_smmu_master_sva_enable_iopf(master);
> +	if (!ret)
> +		master->sva_enabled = true;
>  	mutex_unlock(&sva_lock);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
> @@ -476,6 +522,7 @@ int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
>  		mutex_unlock(&sva_lock);
>  		return -EBUSY;
>  	}
> +	arm_smmu_master_sva_disable_iopf(master);
>  	master->sva_enabled = false;
>  	mutex_unlock(&sva_lock);
>  
> 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 d148bb6d4289..363744df8d51 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -32,6 +32,7 @@
>  #include <linux/amba/bus.h>
>  
>  #include "arm-smmu-v3.h"
> +#include "../../iommu-sva-lib.h"
>  
>  static bool disable_bypass = true;
>  module_param(disable_bypass, bool, 0444);
> @@ -315,6 +316,11 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
>  		}
>  		cmd[1] |= FIELD_PREP(CMDQ_PRI_1_RESP, ent->pri.resp);
>  		break;
> +	case CMDQ_OP_RESUME:
> +		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_SID, ent->resume.sid);
> +		cmd[0] |= FIELD_PREP(CMDQ_RESUME_0_RESP, ent->resume.resp);
> +		cmd[1] |= FIELD_PREP(CMDQ_RESUME_1_STAG, ent->resume.stag);
> +		break;
>  	case CMDQ_OP_CMD_SYNC:
>  		if (ent->sync.msiaddr) {
>  			cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_CS, CMDQ_SYNC_0_CS_IRQ);
> @@ -878,6 +884,44 @@ static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
>  	return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
>  }
>  
> +static int arm_smmu_page_response(struct device *dev,
> +				  struct iommu_fault_event *unused,
> +				  struct iommu_page_response *resp)
> +{
> +	struct arm_smmu_cmdq_ent cmd = {0};
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +	int sid = master->streams[0].id;
> +
> +	if (master->stall_enabled) {
> +		cmd.opcode		= CMDQ_OP_RESUME;
> +		cmd.resume.sid		= sid;
> +		cmd.resume.stag		= resp->grpid;
> +		switch (resp->code) {
> +		case IOMMU_PAGE_RESP_INVALID:
> +		case IOMMU_PAGE_RESP_FAILURE:
> +			cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
> +			break;
> +		case IOMMU_PAGE_RESP_SUCCESS:
> +			cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +	} else {
> +		return -ENODEV;
> +	}
> +
> +	arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
> +	/*
> +	 * Don't send a SYNC, it doesn't do anything for RESUME or PRI_RESP.
> +	 * RESUME consumption guarantees that the stalled transaction will be
> +	 * terminated... at some point in the future. PRI_RESP is fire and
> +	 * forget.
> +	 */
> +
> +	return 0;
> +}
> +
>  /* Context descriptor manipulation functions */
>  void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid)
>  {
> @@ -988,7 +1032,6 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
>  	u64 val;
>  	bool cd_live;
>  	__le64 *cdptr;
> -	struct arm_smmu_device *smmu = smmu_domain->smmu;
>  
>  	if (WARN_ON(ssid >= (1 << smmu_domain->s1_cfg.s1cdmax)))
>  		return -E2BIG;
> @@ -1033,8 +1076,7 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
>  			FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) |
>  			CTXDESC_CD_0_V;
>  
> -		/* STALL_MODEL==0b10 && CD.S==0 is ILLEGAL */
> -		if (smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
> +		if (smmu_domain->stall_enabled)
>  			val |= CTXDESC_CD_0_S;
>  	}
>  
> @@ -1278,7 +1320,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>  			 FIELD_PREP(STRTAB_STE_1_STRW, strw));
>  
>  		if (smmu->features & ARM_SMMU_FEAT_STALLS &&
> -		   !(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
> +		    !master->stall_enabled)
>  			dst[1] |= cpu_to_le64(STRTAB_STE_1_S1STALLD);
>  
>  		val |= (s1_cfg->cdcfg.cdtab_dma & STRTAB_STE_0_S1CTXPTR_MASK) |
> @@ -1356,7 +1398,6 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
>  }
>  
>  /* smmu->streams_mutex must be held */
> -__maybe_unused
>  static struct arm_smmu_master *
>  arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
>  {
> @@ -1378,9 +1419,103 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
>  }
>  
>  /* IRQ and event handlers */
> +static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)
> +{
> +	int ret;
> +	u32 reason;
> +	u32 perm = 0;
> +	struct arm_smmu_master *master;
> +	bool ssid_valid = evt[0] & EVTQ_0_SSV;
> +	u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
> +	struct iommu_fault_event fault_evt = { };
> +	struct iommu_fault *flt = &fault_evt.fault;
> +
> +	switch (FIELD_GET(EVTQ_0_ID, evt[0])) {
> +	case EVT_ID_TRANSLATION_FAULT:
> +		reason = IOMMU_FAULT_REASON_PTE_FETCH;
> +		break;
> +	case EVT_ID_ADDR_SIZE_FAULT:
> +		reason = IOMMU_FAULT_REASON_OOR_ADDRESS;
> +		break;
> +	case EVT_ID_ACCESS_FAULT:
> +		reason = IOMMU_FAULT_REASON_ACCESS;
> +		break;
> +	case EVT_ID_PERMISSION_FAULT:
> +		reason = IOMMU_FAULT_REASON_PERMISSION;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	/* Stage-2 is always pinned at the moment */
> +	if (evt[1] & EVTQ_1_S2)
> +		return -EFAULT;
> +
> +	if (evt[1] & EVTQ_1_RnW)
> +		perm |= IOMMU_FAULT_PERM_READ;
> +	else
> +		perm |= IOMMU_FAULT_PERM_WRITE;
> +
> +	if (evt[1] & EVTQ_1_InD)
> +		perm |= IOMMU_FAULT_PERM_EXEC;
> +
> +	if (evt[1] & EVTQ_1_PnU)
> +		perm |= IOMMU_FAULT_PERM_PRIV;
> +
> +	if (evt[1] & EVTQ_1_STALL) {
> +		flt->type = IOMMU_FAULT_PAGE_REQ;
> +		flt->prm = (struct iommu_fault_page_request) {
> +			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
> +			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
> +			.perm = perm,
> +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> +		};
> +
> +		if (ssid_valid) {
> +			flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
> +			flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
> +		}
> +	} else {
> +		flt->type = IOMMU_FAULT_DMA_UNRECOV;
> +		flt->event = (struct iommu_fault_unrecoverable) {
> +			.reason = reason,
> +			.flags = IOMMU_FAULT_UNRECOV_ADDR_VALID,
> +			.perm = perm,
> +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> +		};
> +
> +		if (ssid_valid) {
> +			flt->event.flags |= IOMMU_FAULT_UNRECOV_PASID_VALID;
> +			flt->event.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
> +		}
> +	}
> +
> +	mutex_lock(&smmu->streams_mutex);
> +	master = arm_smmu_find_master(smmu, sid);
> +	if (!master) {
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +
> +	ret = iommu_report_device_fault(master->dev, &fault_evt);
> +	if (ret && flt->type == IOMMU_FAULT_PAGE_REQ) {
> +		/* Nobody cared, abort the access */
> +		struct iommu_page_response resp = {
> +			.pasid		= flt->prm.pasid,
> +			.grpid		= flt->prm.grpid,
> +			.code		= IOMMU_PAGE_RESP_FAILURE,
> +		};
> +		arm_smmu_page_response(master->dev, &fault_evt, &resp);
> +	}
> +
> +out_unlock:
> +	mutex_unlock(&smmu->streams_mutex);
> +	return ret;
> +}
> +
>  static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>  {
> -	int i;
> +	int i, ret;
>  	struct arm_smmu_device *smmu = dev;
>  	struct arm_smmu_queue *q = &smmu->evtq.q;
>  	struct arm_smmu_ll_queue *llq = &q->llq;
> @@ -1390,6 +1525,10 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>  		while (!queue_remove_raw(q, evt)) {
>  			u8 id = FIELD_GET(EVTQ_0_ID, evt[0]);
>  
> +			ret = arm_smmu_handle_evt(smmu, evt);
> +			if (!ret)
> +				continue;
> +
>  			dev_info(smmu->dev, "event 0x%02x received:\n", id);
>  			for (i = 0; i < ARRAY_SIZE(evt); ++i)
>  				dev_info(smmu->dev, "\t0x%016llx\n",
> @@ -1924,6 +2063,8 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
>  
>  	cfg->s1cdmax = master->ssid_bits;
>  
> +	smmu_domain->stall_enabled = master->stall_enabled;
> +
>  	ret = arm_smmu_alloc_cd_tables(smmu_domain);
>  	if (ret)
>  		goto out_free_asid;
> @@ -2271,6 +2412,12 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
>  			smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
>  		ret = -EINVAL;
>  		goto out_unlock;
> +	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
> +		   smmu_domain->stall_enabled != master->stall_enabled) {
> +		dev_err(dev, "cannot attach to stall-%s domain\n",
> +			smmu_domain->stall_enabled ? "enabled" : "disabled");
> +		ret = -EINVAL;
> +		goto out_unlock;
>  	}
>  
>  	master->domain = smmu_domain;
> @@ -2506,6 +2653,11 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>  		master->ssid_bits = min_t(u8, master->ssid_bits,
>  					  CTXDESC_LINEAR_CDMAX);
>  
> +	if ((smmu->features & ARM_SMMU_FEAT_STALLS &&
> +	     device_property_read_bool(dev, "dma-can-stall")) ||
> +	    smmu->features & ARM_SMMU_FEAT_STALL_FORCE)
> +		master->stall_enabled = true;
> +
>  	return &smmu->iommu;
>  
>  err_free_master:
> @@ -2523,7 +2675,8 @@ static void arm_smmu_release_device(struct device *dev)
>  		return;
>  
>  	master = dev_iommu_priv_get(dev);
> -	WARN_ON(arm_smmu_master_sva_enabled(master));
> +	if (WARN_ON(arm_smmu_master_sva_enabled(master)))
> +		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
>  	arm_smmu_detach_dev(master);
>  	arm_smmu_disable_pasid(master);
>  	arm_smmu_remove_master(master);
> @@ -2651,6 +2804,8 @@ static bool arm_smmu_dev_has_feature(struct device *dev,
>  		return false;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		return arm_smmu_master_iopf_supported(master);
>  	case IOMMU_DEV_FEAT_SVA:
>  		return arm_smmu_master_sva_supported(master);
>  	default:
> @@ -2667,6 +2822,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
>  		return false;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		return master->iopf_enabled;
>  	case IOMMU_DEV_FEAT_SVA:
>  		return arm_smmu_master_sva_enabled(master);
>  	default:
> @@ -2677,6 +2834,8 @@ static bool arm_smmu_dev_feature_enabled(struct device *dev,
>  static int arm_smmu_dev_enable_feature(struct device *dev,
>  				       enum iommu_dev_features feat)
>  {
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +
>  	if (!arm_smmu_dev_has_feature(dev, feat))
>  		return -ENODEV;
>  
> @@ -2684,8 +2843,11 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
>  		return -EBUSY;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		master->iopf_enabled = true;
> +		return 0;
>  	case IOMMU_DEV_FEAT_SVA:
> -		return arm_smmu_master_enable_sva(dev_iommu_priv_get(dev));
> +		return arm_smmu_master_enable_sva(master);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -2694,12 +2856,19 @@ static int arm_smmu_dev_enable_feature(struct device *dev,
>  static int arm_smmu_dev_disable_feature(struct device *dev,
>  					enum iommu_dev_features feat)
>  {
> +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> +
>  	if (!arm_smmu_dev_feature_enabled(dev, feat))
>  		return -EINVAL;
>  
>  	switch (feat) {
> +	case IOMMU_DEV_FEAT_IOPF:
> +		if (master->sva_enabled)
> +			return -EBUSY;
> +		master->iopf_enabled = false;
> +		return 0;
>  	case IOMMU_DEV_FEAT_SVA:
> -		return arm_smmu_master_disable_sva(dev_iommu_priv_get(dev));
> +		return arm_smmu_master_disable_sva(master);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -2730,6 +2899,7 @@ static struct iommu_ops arm_smmu_ops = {
>  	.sva_bind		= arm_smmu_sva_bind,
>  	.sva_unbind		= arm_smmu_sva_unbind,
>  	.sva_get_pasid		= arm_smmu_sva_get_pasid,
> +	.page_response		= arm_smmu_page_response,
>  	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
>  };
>  
> @@ -2827,6 +2997,13 @@ static int arm_smmu_init_queues(struct arm_smmu_device *smmu)
>  	if (ret)
>  		return ret;
>  
> +	if ((smmu->features & ARM_SMMU_FEAT_SVA) &&
> +	    (smmu->features & ARM_SMMU_FEAT_STALLS)) {
> +		smmu->evtq.iopf = iopf_queue_alloc(dev_name(smmu->dev));
> +		if (!smmu->evtq.iopf)
> +			return -ENOMEM;
> +	}
> +
>  	/* priq */
>  	if (!(smmu->features & ARM_SMMU_FEAT_PRI))
>  		return 0;
> @@ -3742,6 +3919,7 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
>  	iommu_device_unregister(&smmu->iommu);
>  	iommu_device_sysfs_remove(&smmu->iommu);
>  	arm_smmu_device_disable(smmu);
> +	iopf_queue_free(smmu->evtq.iopf);
>  
>  	return 0;
>  }
> 

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RE: [PATCH v13 00/10] iommu: I/O page faults for SMMUv3

[Krishna Reddy]

Tested-by: Krishna Reddy <vdumpa@nvidia.com>

Validated v13 patches in context of nested translations validation for NVMe PCIe device assigned to Guest VM.
V12 patches(v13 is yet to be tested) has been tested for SVA functionality on Native OS and is functional. 

-KR

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Re: [PATCH v13 00/10] iommu: I/O page faults for SMMUv3

[Jean-Philippe Brucker]

Hi Will, Joerg,

On Tue, Mar 02, 2021 at 10:26:36AM +0100, Jean-Philippe Brucker wrote:
> Add stall support to the SMMUv3 driver, along with a common I/O Page
> Fault handler.

I only have review/ack tags and one assert_lockdep to add to this series.
Should I send a v14 now or wait a little longer?  Just making sure we can
get at least patches 1-6 in v5.13.

Thanks,
Jean

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Re: [PATCH v13 00/10] iommu: I/O page faults for SMMUv3

[Will Deacon]

On Tue, Mar 30, 2021 at 07:17:55PM +0200, Jean-Philippe Brucker wrote:
> On Tue, Mar 02, 2021 at 10:26:36AM +0100, Jean-Philippe Brucker wrote:
> > Add stall support to the SMMUv3 driver, along with a common I/O Page
> > Fault handler.
> 
> I only have review/ack tags and one assert_lockdep to add to this series.
> Should I send a v14 now or wait a little longer?  Just making sure we can
> get at least patches 1-6 in v5.13.

Easiest thing is probably to send a v14 containing just the patches
targetting v5.13, so that Joerg can queue them up.

Will
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