[PATCH v3 0/6] Define EINVAL as device/domain incompatibility

[PATCH v3 0/6] Define EINVAL as device/domain incompatibility

[Nicolin Chen]

This series is to replace the previous EMEDIUMTYPE patch in a VFIO series:
https://lore.kernel.org/kvm/Yxnt9uQTmbqul5lf@8bytes.org/

The purpose is to regulate all existing ->attach_dev callback functions to
use EINVAL exclusively for an incompatibility error between a device and a
domain. This allows VFIO and IOMMUFD to detect such a soft error, and then
try a different domain with the same device.

Among all the patches, the first two are preparatory changes. And then one
patch to update kdocs and another three patches for the enforcement effort.

Although it might be ideal to merge the previous VFIO series together with
this series, given the number of new changes, the review in the IOMMU list
might need a couple of rounds to finalize. Also, considering that v6.0 is
at rc5 now, perhaps we could merge this IOMMU series and the VFIO one in
different cycles to avoid merge conflicts. If there's less concern for it,
I can respin the finalized version of this series with the previous VFIO
one to merge together into the VFIO tree.

This series is also available on Github:
https://github.com/nicolinc/iommufd/commits/iommu_attach_dev-v3

Changelog
v3:
 * Added "Reviewed-by" from Vasant to the AMD patch
 * Dropped all unnecessary errno enforcement patches
 * Updated kdocs and brought back the kdocs for the helpers
 * Added a separate patch to propagate "ret" for potential EINVALs
 * Converted to ENODEV those existing EINVAL places that are device-specific
v2: https://lore.kernel.org/linux-iommu/20220914051234.10006-1-nicolinc@nvidia.com/
 * Fixed kdocs format
 * Grouped with the virtio patch from Jean (with a small change)
 * Separated previous ENODEV and EINVAL changes to per-driver ones
 * Redone some of the changes to have explicit return values in the
   ->attach_dev() callback functions or their direct sub-functions.
v1: https://lore.kernel.org/linux-iommu/20220913082448.31120-1-nicolinc@nvidia.com/

Thanks!

Nicolin Chen (6):
  iommu/msm: Add missing __disable_clocks calls
  iommu/amd: Drop unnecessary checks in amd_iommu_attach_device()
  iommu: Add return value rules to attach_dev op and APIs
  iommu: Regulate EINVAL in ->attach_dev callback functions
  iommu: Use EINVAL for incompatible device/domain in ->attach_dev
  iommu: Propagate ret for a potential soft failure EINVAL

 drivers/iommu/amd/iommu.c                   | 12 ++---------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 +---------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  3 ---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  7 +-----
 drivers/iommu/fsl_pamu.c                    |  2 +-
 drivers/iommu/fsl_pamu_domain.c             |  4 ++--
 drivers/iommu/intel/iommu.c                 | 10 +++------
 drivers/iommu/intel/pasid.c                 |  6 ++++--
 drivers/iommu/iommu.c                       | 24 +++++++++++++++++++++
 drivers/iommu/ipmmu-vmsa.c                  |  2 --
 drivers/iommu/msm_iommu.c                   |  2 ++
 drivers/iommu/mtk_iommu.c                   |  4 ++--
 drivers/iommu/omap-iommu.c                  |  6 +++---
 drivers/iommu/sprd-iommu.c                  |  4 +---
 drivers/iommu/tegra-gart.c                  |  2 +-
 drivers/iommu/virtio-iommu.c                |  5 ++---
 include/linux/iommu.h                       | 12 +++++++++++
 17 files changed, 61 insertions(+), 55 deletions(-)

-- 
2.17.1


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[PATCH v3 3/6] iommu: Add return value rules to attach_dev op and APIs

[Nicolin Chen]

Cases like VFIO wish to attach a device to an existing domain that was
not allocated specifically from the device. This raises a condition
where the IOMMU driver can fail the domain attach because the domain and
device are incompatible with each other.

This is a soft failure that can be resolved by using a different domain.

Provide a dedicated errno EINVAL from the IOMMU driver during attach that
the reason why the attach failed is because of domain incompatibility.

VFIO can use this to know that the attach is a soft failure and it should
continue searching. Otherwise, the attach will be a hard failure and VFIO
will return the code to userspace.

Update kdocs to add rules of return value to the attach_dev op and APIs.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommu.c | 24 ++++++++++++++++++++++++
 include/linux/iommu.h | 12 ++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3a808146b50f..e4d2ee99a264 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1975,6 +1975,18 @@ static int __iommu_attach_device(struct iommu_domain *domain,
 	return ret;
 }
 
+/**
+ * iommu_attach_device - Attach a device to an IOMMU domain
+ * @domain: IOMMU domain to attach
+ * @dev: Device that will be attached
+ *
+ * Returns 0 on success and error code on failure
+ *
+ * Note that EINVAL may be returned as a soft failure if the domain and device
+ * are incompatible: if the domain has already been used or configured in some
+ * way, attaching the same device to a different domain may succeed. Otherwise,
+ * it may still represent some fundamental problem.
+ */
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2101,6 +2113,18 @@ static int __iommu_attach_group(struct iommu_domain *domain,
 	return ret;
 }
 
+/**
+ * iommu_attach_group - Attach an IOMMU group to an IOMMU domain
+ * @domain: IOMMU domain to attach
+ * @group: IOMMU group that will be attached
+ *
+ * Returns 0 on success and error code on failure
+ *
+ * Note that EINVAL may be returned as a soft failure if the domain and group
+ * are incompatible: if the domain has already been used or configured in some
+ * way, attaching the same group to a different domain may succeed. Otherwise,
+ * it may still represent some fundamental problem.
+ */
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	int ret;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ea30f00dc145..90960fa8cd91 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -266,6 +266,18 @@ struct iommu_ops {
 /**
  * struct iommu_domain_ops - domain specific operations
  * @attach_dev: attach an iommu domain to a device
+ *  Return:
+ * * 0		- success
+ * * EINVAL	- the device and domain are incompatible. If this is due to some
+ *		  previous configuration of the domain, drivers shouldn't log an
+ *		  error, since it is legitimate for a caller to test reuse of an
+ *		  existing domain. Otherwise, it may still represent some other
+ *		  fundamental problem
+ * * ENOMEM	- out of memory
+ * * ENOSPC	- non-ENOMEM type of resource allocation failures
+ * * EBUSY	- device is attached to a domain and cannot be changed
+ * * ENODEV	- device specific errors, not able to be attached
+ * * <others>	- treated as ENODEV by the caller. Use is discouraged
  * @detach_dev: detach an iommu domain from a device
  * @map: map a physically contiguous memory region to an iommu domain
  * @map_pages: map a physically contiguous set of pages of the same size to
-- 
2.17.1


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RE: [PATCH v3 3/6] iommu: Add return value rules to attach_dev op and APIs

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Thursday, September 15, 2022 3:54 PM
> 
> +/**
> + * iommu_attach_device - Attach a device to an IOMMU domain
> + * @domain: IOMMU domain to attach
> + * @dev: Device that will be attached
> + *
> + * Returns 0 on success and error code on failure
> + *
> + * Note that EINVAL may be returned as a soft failure if the domain and
> device
> + * are incompatible: if the domain has already been used or configured in
> some

I didn't get the meaning of the 'if' part.

> + * way, attaching the same device to a different domain may succeed.
> Otherwise,
> + * it may still represent some fundamental problem.

I'm not sure what the sentence after 'otherwise' actually adds to the
caller. There is no way to differentiate incompatibility vs. fundamental
problem, hence pointless for the caller to know this fact.

IMHO just state that the caller can treat -EINVAL as soft failure indicating
incompatibility issue between domain and device.

Later for @attach_dev you can add that driver may return (but not
recommend) -EINVAL for some fundamental problems.


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Re: [PATCH v3 3/6] iommu: Add return value rules to attach_dev op and APIs

[Nicolin Chen]

On Tue, Sep 20, 2022 at 06:24:58AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Thursday, September 15, 2022 3:54 PM
> >
> > +/**
> > + * iommu_attach_device - Attach a device to an IOMMU domain
> > + * @domain: IOMMU domain to attach
> > + * @dev: Device that will be attached
> > + *
> > + * Returns 0 on success and error code on failure
> > + *
> > + * Note that EINVAL may be returned as a soft failure if the domain and
> > device
> > + * are incompatible: if the domain has already been used or configured in
> > some
> 
> I didn't get the meaning of the 'if' part.

It means that the failure of attaching the device to the domain is
due to the domain configuration.

> > + * way, attaching the same device to a different domain may succeed.
> > Otherwise,
> > + * it may still represent some fundamental problem.
> 
> I'm not sure what the sentence after 'otherwise' actually adds to the
> caller. There is no way to differentiate incompatibility vs. fundamental
> problem, hence pointless for the caller to know this fact.
> 
> IMHO just state that the caller can treat -EINVAL as soft failure indicating
> incompatibility issue between domain and device.

OK. I changed to:
+ * Note that EINVAL may be returned as a soft failure if the domain and device
+ * are incompatible due to some previous configuration of the domain, in which
+ * case attaching the same device to a different domain may succeed.

> Later for @attach_dev you can add that driver may return (but not
> recommend) -EINVAL for some fundamental problems.

OK.

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[PATCH v3 5/6] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Nicolin Chen]

Following the new rules in include/linux/iommu.h kdocs, update all drivers
->attach_dev callback functions to return EINVAL in the failure paths that
are related to domain incompatibility.

Also, drop adjacent error prints to prevent a kernel log spam.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 +----------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  3 ---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  7 +------
 drivers/iommu/intel/iommu.c                 | 10 +++-------
 drivers/iommu/ipmmu-vmsa.c                  |  2 --
 drivers/iommu/omap-iommu.c                  |  2 +-
 drivers/iommu/sprd-iommu.c                  |  4 +---
 drivers/iommu/tegra-gart.c                  |  2 +-
 drivers/iommu/virtio-iommu.c                |  3 +--
 9 files changed, 9 insertions(+), 35 deletions(-)

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 d32b02336411..f96f8aad8280 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2429,23 +2429,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 			goto out_unlock;
 		}
 	} else if (smmu_domain->smmu != smmu) {
-		dev_err(dev,
-			"cannot attach to SMMU %s (upstream of %s)\n",
-			dev_name(smmu_domain->smmu->dev),
-			dev_name(smmu->dev));
-		ret = -ENXIO;
+		ret = -EINVAL;
 		goto out_unlock;
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
 		   master->ssid_bits != smmu_domain->s1_cfg.s1cdmax) {
-		dev_err(dev,
-			"cannot attach to incompatible domain (%u SSID bits != %u)\n",
-			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;
 	}
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index dfa82df00342..dbd12da31707 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1167,9 +1167,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	 * different SMMUs.
 	 */
 	if (smmu_domain->smmu != smmu) {
-		dev_err(dev,
-			"cannot attach to SMMU %s whilst already attached to domain on SMMU %s\n",
-			dev_name(smmu_domain->smmu->dev), dev_name(smmu->dev));
 		ret = -EINVAL;
 		goto rpm_put;
 	}
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 17235116d3bb..37c5ddc212c1 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -381,13 +381,8 @@ static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev
 	 * Sanity check the domain. We don't support domains across
 	 * different IOMMUs.
 	 */
-	if (qcom_domain->iommu != qcom_iommu) {
-		dev_err(dev, "cannot attach to IOMMU %s while already "
-			"attached to domain on IOMMU %s\n",
-			dev_name(qcom_domain->iommu->dev),
-			dev_name(qcom_iommu->dev));
+	if (qcom_domain->iommu != qcom_iommu)
 		return -EINVAL;
-	}
 
 	return 0;
 }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 1f2cd43cf9bc..51ef42b1bd4e 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4158,19 +4158,15 @@ static int prepare_domain_attach_device(struct iommu_domain *domain,
 		return -ENODEV;
 
 	if (dmar_domain->force_snooping && !ecap_sc_support(iommu->ecap))
-		return -EOPNOTSUPP;
+		return -EINVAL;
 
 	/* check if this iommu agaw is sufficient for max mapped address */
 	addr_width = agaw_to_width(iommu->agaw);
 	if (addr_width > cap_mgaw(iommu->cap))
 		addr_width = cap_mgaw(iommu->cap);
 
-	if (dmar_domain->max_addr > (1LL << addr_width)) {
-		dev_err(dev, "%s: iommu width (%d) is not "
-		        "sufficient for the mapped address (%llx)\n",
-		        __func__, addr_width, dmar_domain->max_addr);
-		return -EFAULT;
-	}
+	if (dmar_domain->max_addr > (1LL << addr_width))
+		return -EINVAL;
 	dmar_domain->gaw = addr_width;
 
 	/*
diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 1d42084d0276..f5217a4cb9b3 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -628,8 +628,6 @@ static int ipmmu_attach_device(struct iommu_domain *io_domain,
 		 * Something is wrong, we can't attach two devices using
 		 * different IOMMUs to the same domain.
 		 */
-		dev_err(dev, "Can't attach IPMMU %s to domain on IPMMU %s\n",
-			dev_name(mmu->dev), dev_name(domain->mmu->dev));
 		ret = -EINVAL;
 	} else
 		dev_info(dev, "Reusing IPMMU context %u\n", domain->context_id);
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index 447e40d55918..be12f49140c7 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1472,7 +1472,7 @@ omap_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	/* only a single client device can be attached to a domain */
 	if (omap_domain->dev) {
 		dev_err(dev, "iommu domain is already attached\n");
-		ret = -EBUSY;
+		ret = -EINVAL;
 		goto out;
 	}
 
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index 511959c8a14d..945576039c9e 100644
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -237,10 +237,8 @@ static int sprd_iommu_attach_device(struct iommu_domain *domain,
 	struct sprd_iommu_domain *dom = to_sprd_domain(domain);
 	size_t pgt_size = sprd_iommu_pgt_size(domain);
 
-	if (dom->sdev) {
-		pr_err("There's already a device attached to this domain.\n");
+	if (dom->sdev)
 		return -EINVAL;
-	}
 
 	dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
 	if (!dom->pgt_va)
diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
index e5ca3cf1a949..ed53279d1106 100644
--- a/drivers/iommu/tegra-gart.c
+++ b/drivers/iommu/tegra-gart.c
@@ -112,7 +112,7 @@ static int gart_iommu_attach_dev(struct iommu_domain *domain,
 	spin_lock(&gart->dom_lock);
 
 	if (gart->active_domain && gart->active_domain != domain) {
-		ret = -EBUSY;
+		ret = -EINVAL;
 	} else if (dev_iommu_priv_get(dev) != domain) {
 		dev_iommu_priv_set(dev, domain);
 		gart->active_domain = domain;
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 80151176ba12..caca0a638c4d 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -733,8 +733,7 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		 */
 		ret = viommu_domain_finalise(vdev, domain);
 	} else if (vdomain->viommu != vdev->viommu) {
-		dev_err(dev, "cannot attach to foreign vIOMMU\n");
-		ret = -EXDEV;
+		ret = -EINVAL;
 	}
 	mutex_unlock(&vdomain->mutex);
 
-- 
2.17.1


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RE: [PATCH v3 5/6] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Thursday, September 15, 2022 3:54 PM
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 1f2cd43cf9bc..51ef42b1bd4e 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4158,19 +4158,15 @@ static int prepare_domain_attach_device(struct
> iommu_domain *domain,
>  		return -ENODEV;
> 
>  	if (dmar_domain->force_snooping && !ecap_sc_support(iommu-
> >ecap))
> -		return -EOPNOTSUPP;
> +		return -EINVAL;
> 
>  	/* check if this iommu agaw is sufficient for max mapped address */
>  	addr_width = agaw_to_width(iommu->agaw);
>  	if (addr_width > cap_mgaw(iommu->cap))
>  		addr_width = cap_mgaw(iommu->cap);
> 
> -	if (dmar_domain->max_addr > (1LL << addr_width)) {
> -		dev_err(dev, "%s: iommu width (%d) is not "
> -		        "sufficient for the mapped address (%llx)\n",
> -		        __func__, addr_width, dmar_domain->max_addr);
> -		return -EFAULT;
> -	}
> +	if (dmar_domain->max_addr > (1LL << addr_width))
> +		return -EINVAL;
>  	dmar_domain->gaw = addr_width;
> 
>  	/*

Above lacks of a conversion in intel-iommu:

intel_iommu_attach_device()
	if (domain->type == IOMMU_DOMAIN_UNMANAGED &&
	    device_is_rmrr_locked(dev)) {
		dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
		return -EPERM;
	}

since it's based on the domain type, picking a different domain
may work in theory though it won't apply to vfio which always
creates unmanaged type.

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Re: [PATCH v3 5/6] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Jason Gunthorpe]

On Tue, Sep 20, 2022 at 06:38:18AM +0000, Tian, Kevin wrote:

> Above lacks of a conversion in intel-iommu:
> 
> intel_iommu_attach_device()
> 	if (domain->type == IOMMU_DOMAIN_UNMANAGED &&
> 	    device_is_rmrr_locked(dev)) {
> 		dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
> 		return -EPERM;
> 	}
> 
> since it's based on the domain type, picking a different domain
> may work in theory though it won't apply to vfio which always
> creates unmanaged type.

IMHO this test shouldn't even be here, that is why it is so
strange..

VFIO should be checking if somehow the device doesn't support
unmanaged domains at all. We already have several drivers that can't
support full featured unamanged domains that vfio needs, this is just
another case of that.

But it isn't urgent to fix, I would just ignore this branch for this
series.

Jason


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RE: [PATCH v3 5/6] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Wednesday, September 21, 2022 2:07 AM
> 
> On Tue, Sep 20, 2022 at 06:38:18AM +0000, Tian, Kevin wrote:
> 
> > Above lacks of a conversion in intel-iommu:
> >
> > intel_iommu_attach_device()
> > 	if (domain->type == IOMMU_DOMAIN_UNMANAGED &&
> > 	    device_is_rmrr_locked(dev)) {
> > 		dev_warn(dev, "Device is ineligible for IOMMU domain
> attach due to platform RMRR requirement.  Contact your platform
> vendor.\n");
> > 		return -EPERM;
> > 	}
> >
> > since it's based on the domain type, picking a different domain
> > may work in theory though it won't apply to vfio which always
> > creates unmanaged type.
> 
> IMHO this test shouldn't even be here, that is why it is so
> strange..
> 
> VFIO should be checking if somehow the device doesn't support
> unmanaged domains at all. We already have several drivers that can't
> support full featured unamanged domains that vfio needs, this is just
> another case of that.
> 
> But it isn't urgent to fix, I would just ignore this branch for this
> series.
> 

OK, then let's leave it as is. Anyway this is a rare path. In reality
most RMRR devices are gpu/usb which are already exempted
from the above check.

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[PATCH v3 4/6] iommu: Regulate EINVAL in ->attach_dev callback functions

[Nicolin Chen]

Following the new rules in include/linux/iommu.h kdocs, EINVAL now can be
used to indicate that domain and device are incompatible by a caller that
treats it as a soft failure and tries attaching to another domain.

On the other hand, there are ->attach_dev callback functions returning it
for obvious device-specific errors. They will result in some inefficiency
in the caller handling routine.

Update these places to corresponding errnos following the new rules.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/fsl_pamu.c        | 2 +-
 drivers/iommu/fsl_pamu_domain.c | 4 ++--
 drivers/iommu/intel/pasid.c     | 6 ++++--
 drivers/iommu/mtk_iommu.c       | 2 +-
 drivers/iommu/omap-iommu.c      | 4 ++--
 5 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c
index 0d03f837a5d4..2eb3211c8167 100644
--- a/drivers/iommu/fsl_pamu.c
+++ b/drivers/iommu/fsl_pamu.c
@@ -211,7 +211,7 @@ int pamu_config_ppaace(int liodn, u32 omi, u32 stashid, int prot)
 		ppaace->op_encode.index_ot.omi = omi;
 	} else if (~omi != 0) {
 		pr_debug("bad operation mapping index: %d\n", omi);
-		return -EINVAL;
+		return -ENODEV;
 	}
 
 	/* configure stash id */
diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index 011f9ab7f743..b4a1c0f79c3e 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -258,7 +258,7 @@ static int fsl_pamu_attach_device(struct iommu_domain *domain,
 	liodn = of_get_property(dev->of_node, "fsl,liodn", &len);
 	if (!liodn) {
 		pr_debug("missing fsl,liodn property at %pOF\n", dev->of_node);
-		return -EINVAL;
+		return -ENODEV;
 	}
 
 	spin_lock_irqsave(&dma_domain->domain_lock, flags);
@@ -267,7 +267,7 @@ static int fsl_pamu_attach_device(struct iommu_domain *domain,
 		if (liodn[i] >= PAACE_NUMBER_ENTRIES) {
 			pr_debug("Invalid liodn %d, attach device failed for %pOF\n",
 				 liodn[i], dev->of_node);
-			ret = -EINVAL;
+			ret = -ENODEV;
 			break;
 		}
 
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index c5e7e8b020a5..4cadbd744b7f 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -101,8 +101,10 @@ int intel_pasid_alloc_table(struct device *dev)
 
 	might_sleep();
 	info = dev_iommu_priv_get(dev);
-	if (WARN_ON(!info || !dev_is_pci(dev) || info->pasid_table))
-		return -EINVAL;
+	if (WARN_ON(!info || !dev_is_pci(dev)))
+		return -ENODEV;
+	if (WARN_ON(info->pasid_table))
+		return -EBUSY;
 
 	pasid_table = kzalloc(sizeof(*pasid_table), GFP_KERNEL);
 	if (!pasid_table)
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 7e363b1f24df..be1a7d1cc630 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -607,7 +607,7 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom,
 	dom->iop = alloc_io_pgtable_ops(ARM_V7S, &dom->cfg, data);
 	if (!dom->iop) {
 		dev_err(data->dev, "Failed to alloc io pgtable\n");
-		return -EINVAL;
+		return -ENOMEM;
 	}
 
 	/* Update our support page sizes bitmap */
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index d9cf2820c02e..447e40d55918 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1414,7 +1414,7 @@ static int omap_iommu_attach_init(struct device *dev,
 
 	odomain->num_iommus = omap_iommu_count(dev);
 	if (!odomain->num_iommus)
-		return -EINVAL;
+		return -ENODEV;
 
 	odomain->iommus = kcalloc(odomain->num_iommus, sizeof(*iommu),
 				  GFP_ATOMIC);
@@ -1464,7 +1464,7 @@ omap_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	if (!arch_data || !arch_data->iommu_dev) {
 		dev_err(dev, "device doesn't have an associated iommu\n");
-		return -EINVAL;
+		return -ENODEV;
 	}
 
 	spin_lock(&omap_domain->lock);
-- 
2.17.1


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RE: [PATCH v3 4/6] iommu: Regulate EINVAL in ->attach_dev callback functions

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Thursday, September 15, 2022 3:59 PM
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index c5e7e8b020a5..4cadbd744b7f 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -101,8 +101,10 @@ int intel_pasid_alloc_table(struct device *dev)
> 
>  	might_sleep();
>  	info = dev_iommu_priv_get(dev);
> -	if (WARN_ON(!info || !dev_is_pci(dev) || info->pasid_table))
> -		return -EINVAL;
> +	if (WARN_ON(!info || !dev_is_pci(dev)))
> +		return -ENODEV;
> +	if (WARN_ON(info->pasid_table))
> +		return -EBUSY;

-EEXIST. It's not a busy condition which might change sometime after.

btw below -EVINAL in viommu should be converted to -ENODEV too
since it's a check purely on device side:

viommu_domain_finalise()
        viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap);
        if (viommu_page_size > PAGE_SIZE) {
                dev_err(vdev->dev,
                        "granule 0x%lx larger than system page size 0x%lx\n",
                        viommu_page_size, PAGE_SIZE);
                return -EINVAL;
        }

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Re: [PATCH v3 4/6] iommu: Regulate EINVAL in ->attach_dev callback functions

[Nicolin Chen]

On Tue, Sep 20, 2022 at 06:29:28AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Thursday, September 15, 2022 3:59 PM
> >
> > diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> > index c5e7e8b020a5..4cadbd744b7f 100644
> > --- a/drivers/iommu/intel/pasid.c
> > +++ b/drivers/iommu/intel/pasid.c
> > @@ -101,8 +101,10 @@ int intel_pasid_alloc_table(struct device *dev)
> >
> >       might_sleep();
> >       info = dev_iommu_priv_get(dev);
> > -     if (WARN_ON(!info || !dev_is_pci(dev) || info->pasid_table))
> > -             return -EINVAL;
> > +     if (WARN_ON(!info || !dev_is_pci(dev)))
> > +             return -ENODEV;
> > +     if (WARN_ON(info->pasid_table))
> > +             return -EBUSY;
> 
> -EEXIST. It's not a busy condition which might change sometime after.
> 
> btw below -EVINAL in viommu should be converted to -ENODEV too
> since it's a check purely on device side:
> 
> viommu_domain_finalise()
>         viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap);
>         if (viommu_page_size > PAGE_SIZE) {
>                 dev_err(vdev->dev,
>                         "granule 0x%lx larger than system page size 0x%lx\n",
>                         viommu_page_size, PAGE_SIZE);
>                 return -EINVAL;
>         }

Fixed both places. Thanks!


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[PATCH v3 6/6] iommu: Propagate ret for a potential soft failure EINVAL

[Nicolin Chen]

Following the new rules in include/linux/iommu.h kdocs, EINVAL now can be
used to indicate that domain and device are incompatible by a caller that
treats it as a soft failure and tries attaching to another domain.

Either mtk_iommu or virtio driver has a place that returns a hard failure
instead of the return value from the function call, where an incompatible
errno EINVAL could potentially occur.

Propagate the real return value to not miss a potential soft failure.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/mtk_iommu.c    | 2 +-
 drivers/iommu/virtio-iommu.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index be1a7d1cc630..c30dc8f81778 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -666,7 +666,7 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 		ret = mtk_iommu_domain_finalise(dom, frstdata, region_id);
 		if (ret) {
 			mutex_unlock(&dom->mutex);
-			return -ENODEV;
+			return ret;
 		}
 		dom->bank = &data->bank[bankid];
 	}
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index caca0a638c4d..f1ecc5589626 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -696,7 +696,7 @@ static int viommu_domain_finalise(struct viommu_endpoint *vdev,
 		if (ret) {
 			ida_free(&viommu->domain_ids, vdomain->id);
 			vdomain->viommu = NULL;
-			return -EOPNOTSUPP;
+			return ret;
 		}
 	}
 
-- 
2.17.1


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RE: [PATCH v3 6/6] iommu: Propagate ret for a potential soft failure EINVAL

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Thursday, September 15, 2022 3:59 PM
> 
> Following the new rules in include/linux/iommu.h kdocs, EINVAL now can be
> used to indicate that domain and device are incompatible by a caller that
> treats it as a soft failure and tries attaching to another domain.
> 
> Either mtk_iommu or virtio driver has a place that returns a hard failure
> instead of the return value from the function call, where an incompatible
> errno EINVAL could potentially occur.

in both cases there is no EINVAL returned from the calling stack

IMHO error propagation is the right way even w/o talking about EINVAL
otherwise we may miss ENOMEM etc.

> 
> Propagate the real return value to not miss a potential soft failure.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Apart from that comment,

Reviewed-by: Kevin Tian <kevin.tian@intel.com>

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Re: [PATCH v3 6/6] iommu: Propagate ret for a potential soft failure EINVAL

[Nicolin Chen]

On Tue, Sep 20, 2022 at 06:50:22AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Thursday, September 15, 2022 3:59 PM
> >
> > Following the new rules in include/linux/iommu.h kdocs, EINVAL now can be
> > used to indicate that domain and device are incompatible by a caller that
> > treats it as a soft failure and tries attaching to another domain.
> >
> > Either mtk_iommu or virtio driver has a place that returns a hard failure
> > instead of the return value from the function call, where an incompatible
> > errno EINVAL could potentially occur.
> 
> in both cases there is no EINVAL returned from the calling stack
> 
> IMHO error propagation is the right way even w/o talking about EINVAL
> otherwise we may miss ENOMEM etc.

OK. I changed to:

The mtk_iommu and virtio drivers have places in the ->attach_dev callback
functions that return hardcode errnos instead of the returned values, but
callers of these ->attach_dv callback functions may care. Propagate them
directly without the extra conversions.

> > Propagate the real return value to not miss a potential soft failure.
> >
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> 
> Apart from that comment,
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>

Added this too. Thanks!

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