[PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

This is a preparatory series for IOMMUFD v2 patches. It enforces error
code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
an IOMMU domain and a device/group are incompatible. It also drops the
useless domain->ops check since it won't fail in current environment.

These allow VFIO iommu code to simplify its group attachment routine, by
avoiding the extra IOMMU domain allocations and attach/detach sequences
of the old code.

Worths mentioning the exact match for enforce_cache_coherency is removed
with this series, since there's very less value in doing that as KVM will
not be able to take advantage of it -- this just wastes domain memory.
Instead, we rely on Intel IOMMU driver taking care of that internally.

This is on github:
https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

Changelog
v5:
 * Rebased on top of Robin's "Simplify bus_type determination".
 * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
 * Added Baolu's "Reviewed-by".
v4:
 * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
 * Added Baolu's and Kevin's Reviewed-by lines
v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
 * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
 * Updated commit message of enforce_cache_coherency removing patch.
 * Updated commit message of domain->ops removing patch.
 * Replaced "goto out_unlock" with simply mutex_unlock() and return.
 * Added a line of comments for -EMEDIUMTYPE return check.
 * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
   should be logically tied to the lifetime of a domain itself.
 * Added Kevin's "Reviewed-by".
v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
 * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
 * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
 * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
   since there's no mixed-driver use case that would fail the sanity.
 * Updated commit log of the patch removing enforce_cache_coherency.
 * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
 * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
   domain-reusing and new-domain pathways, like the code previously did.
 * Fixed a typo in EMEDIUMTYPE patch.
v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/

Jason Gunthorpe (1):
  vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
    coherency

Nicolin Chen (4):
  iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
  vfio/iommu_type1: Remove the domain->ops comparison
  vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
  vfio/iommu_type1: Simplify group attachment

 drivers/iommu/amd/iommu.c                   |   2 +-
 drivers/iommu/apple-dart.c                  |   4 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
 drivers/iommu/intel/iommu.c                 |  10 +-
 drivers/iommu/iommu.c                       |  28 ++
 drivers/iommu/ipmmu-vmsa.c                  |   4 +-
 drivers/iommu/omap-iommu.c                  |   3 +-
 drivers/iommu/s390-iommu.c                  |   2 +-
 drivers/iommu/sprd-iommu.c                  |   6 +-
 drivers/iommu/tegra-gart.c                  |   2 +-
 drivers/iommu/virtio-iommu.c                |   3 +-
 drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
 14 files changed, 229 insertions(+), 216 deletions(-)

-- 
2.17.1

[PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen via iommu]

This is a preparatory series for IOMMUFD v2 patches. It enforces error
code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
an IOMMU domain and a device/group are incompatible. It also drops the
useless domain->ops check since it won't fail in current environment.

These allow VFIO iommu code to simplify its group attachment routine, by
avoiding the extra IOMMU domain allocations and attach/detach sequences
of the old code.

Worths mentioning the exact match for enforce_cache_coherency is removed
with this series, since there's very less value in doing that as KVM will
not be able to take advantage of it -- this just wastes domain memory.
Instead, we rely on Intel IOMMU driver taking care of that internally.

This is on github:
https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

Changelog
v5:
 * Rebased on top of Robin's "Simplify bus_type determination".
 * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
 * Added Baolu's "Reviewed-by".
v4:
 * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
 * Added Baolu's and Kevin's Reviewed-by lines
v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
 * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
 * Updated commit message of enforce_cache_coherency removing patch.
 * Updated commit message of domain->ops removing patch.
 * Replaced "goto out_unlock" with simply mutex_unlock() and return.
 * Added a line of comments for -EMEDIUMTYPE return check.
 * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
   should be logically tied to the lifetime of a domain itself.
 * Added Kevin's "Reviewed-by".
v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
 * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
 * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
 * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
   since there's no mixed-driver use case that would fail the sanity.
 * Updated commit log of the patch removing enforce_cache_coherency.
 * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
 * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
   domain-reusing and new-domain pathways, like the code previously did.
 * Fixed a typo in EMEDIUMTYPE patch.
v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/

Jason Gunthorpe (1):
  vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
    coherency

Nicolin Chen (4):
  iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
  vfio/iommu_type1: Remove the domain->ops comparison
  vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
  vfio/iommu_type1: Simplify group attachment

 drivers/iommu/amd/iommu.c                   |   2 +-
 drivers/iommu/apple-dart.c                  |   4 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
 drivers/iommu/intel/iommu.c                 |  10 +-
 drivers/iommu/iommu.c                       |  28 ++
 drivers/iommu/ipmmu-vmsa.c                  |   4 +-
 drivers/iommu/omap-iommu.c                  |   3 +-
 drivers/iommu/s390-iommu.c                  |   2 +-
 drivers/iommu/sprd-iommu.c                  |   6 +-
 drivers/iommu/tegra-gart.c                  |   2 +-
 drivers/iommu/virtio-iommu.c                |   3 +-
 drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
 14 files changed, 229 insertions(+), 216 deletions(-)

-- 
2.17.1

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

[PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

This is a preparatory series for IOMMUFD v2 patches. It enforces error
code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
an IOMMU domain and a device/group are incompatible. It also drops the
useless domain->ops check since it won't fail in current environment.

These allow VFIO iommu code to simplify its group attachment routine, by
avoiding the extra IOMMU domain allocations and attach/detach sequences
of the old code.

Worths mentioning the exact match for enforce_cache_coherency is removed
with this series, since there's very less value in doing that as KVM will
not be able to take advantage of it -- this just wastes domain memory.
Instead, we rely on Intel IOMMU driver taking care of that internally.

This is on github:
https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

Changelog
v5:
 * Rebased on top of Robin's "Simplify bus_type determination".
 * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
 * Added Baolu's "Reviewed-by".
v4:
 * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
 * Added Baolu's and Kevin's Reviewed-by lines
v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
 * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
 * Updated commit message of enforce_cache_coherency removing patch.
 * Updated commit message of domain->ops removing patch.
 * Replaced "goto out_unlock" with simply mutex_unlock() and return.
 * Added a line of comments for -EMEDIUMTYPE return check.
 * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
   should be logically tied to the lifetime of a domain itself.
 * Added Kevin's "Reviewed-by".
v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
 * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
 * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
 * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
   since there's no mixed-driver use case that would fail the sanity.
 * Updated commit log of the patch removing enforce_cache_coherency.
 * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
 * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
   domain-reusing and new-domain pathways, like the code previously did.
 * Fixed a typo in EMEDIUMTYPE patch.
v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/

Jason Gunthorpe (1):
  vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
    coherency

Nicolin Chen (4):
  iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
  vfio/iommu_type1: Remove the domain->ops comparison
  vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
  vfio/iommu_type1: Simplify group attachment

 drivers/iommu/amd/iommu.c                   |   2 +-
 drivers/iommu/apple-dart.c                  |   4 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
 drivers/iommu/intel/iommu.c                 |  10 +-
 drivers/iommu/iommu.c                       |  28 ++
 drivers/iommu/ipmmu-vmsa.c                  |   4 +-
 drivers/iommu/omap-iommu.c                  |   3 +-
 drivers/iommu/s390-iommu.c                  |   2 +-
 drivers/iommu/sprd-iommu.c                  |   6 +-
 drivers/iommu/tegra-gart.c                  |   2 +-
 drivers/iommu/virtio-iommu.c                |   3 +-
 drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
 14 files changed, 229 insertions(+), 216 deletions(-)

-- 
2.17.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

[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 from the IOMMU driver during attach that the
reason attached failed is because of domain incompatability. EMEDIUMTYPE
is chosen because it is never used within the iommu subsystem today and
evokes a sense that the 'medium' aka the domain is incompatible.

VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are
related to domain incompatability. Also remove adjacent error prints for
these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is
clear enough to indicate an incompatability error.

Add kdocs describing this behavior.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/amd/iommu.c                   |  2 +-
 drivers/iommu/apple-dart.c                  |  4 +--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++--------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  5 +---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-----
 drivers/iommu/intel/iommu.c                 | 10 +++-----
 drivers/iommu/iommu.c                       | 28 +++++++++++++++++++++
 drivers/iommu/ipmmu-vmsa.c                  |  4 +--
 drivers/iommu/omap-iommu.c                  |  3 +--
 drivers/iommu/s390-iommu.c                  |  2 +-
 drivers/iommu/sprd-iommu.c                  |  6 ++---
 drivers/iommu/tegra-gart.c                  |  2 +-
 drivers/iommu/virtio-iommu.c                |  3 +--
 13 files changed, 47 insertions(+), 46 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 840831d5d2ad..ad499658a6b6 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1662,7 +1662,7 @@ static int attach_device(struct device *dev,
 	if (domain->flags & PD_IOMMUV2_MASK) {
 		struct iommu_domain *def_domain = iommu_get_dma_domain(dev);
 
-		ret = -EINVAL;
+		ret = -EMEDIUMTYPE;
 		if (def_domain->type != IOMMU_DOMAIN_IDENTITY)
 			goto out;
 
diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 8af0242a90d9..e58dc310afd7 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -495,10 +495,10 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 
 	if (cfg->stream_maps[0].dart->force_bypass &&
 	    domain->type != IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 	if (!cfg->stream_maps[0].dart->supports_bypass &&
 	    domain->type == IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 
 	ret = apple_dart_finalize_domain(domain, cfg);
 	if (ret)
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 88817a3376ef..5b64138f549d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2420,24 +2420,15 @@ 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 = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		goto out_unlock;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 2ed3594f384e..4b95673be076 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1167,10 +1167,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 		goto rpm_put;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 4c077c38fbd6..8372f985c14a 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));
-		return -EINVAL;
-	}
+	if (qcom_domain->iommu != qcom_iommu)
+		return -EMEDIUMTYPE;
 
 	return 0;
 }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 44016594831d..db5fb799e350 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4323,19 +4323,15 @@ 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 -EMEDIUMTYPE;
 
 	/* 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 -EMEDIUMTYPE;
 	dmar_domain->gaw = addr_width;
 
 	/*
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..5b0afe39275e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1972,6 +1972,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2098,6 +2112,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	int ret;
diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 8fdb84b3642b..82d63394b166 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -628,9 +628,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 	} 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 d9cf2820c02e..6bc8925726bf 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1471,8 +1471,7 @@ 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 = -EMEDIUMTYPE;
 		goto out;
 	}
 
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c898bcbbce11..ddcb78b284bb 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -127,7 +127,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 	/* Allow only devices with identical DMA range limits */
 	} else if (domain->geometry.aperture_start != zdev->start_dma ||
 		   domain->geometry.aperture_end != zdev->end_dma) {
-		rc = -EINVAL;
+		rc = -EMEDIUMTYPE;
 		spin_unlock_irqrestore(&s390_domain->list_lock, flags);
 		goto out_restore;
 	}
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index bd409bab6286..f6ae230ca1cd 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");
-		return -EINVAL;
-	}
+	if (dom->sdev)
+		return -EMEDIUMTYPE;
 
 	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 a6700a40a6f8..011c33e6ae31 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 = -EMEDIUMTYPE;
 	} 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 25be4b822aa0..a41a62dccb4d 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 = -EMEDIUMTYPE;
 	}
 	mutex_unlock(&vdomain->mutex);
 
-- 
2.17.1

[PATCH v5 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

[Nicolin Chen via iommu]

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 from the IOMMU driver during attach that the
reason attached failed is because of domain incompatability. EMEDIUMTYPE
is chosen because it is never used within the iommu subsystem today and
evokes a sense that the 'medium' aka the domain is incompatible.

VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are
related to domain incompatability. Also remove adjacent error prints for
these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is
clear enough to indicate an incompatability error.

Add kdocs describing this behavior.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/amd/iommu.c                   |  2 +-
 drivers/iommu/apple-dart.c                  |  4 +--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++--------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  5 +---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-----
 drivers/iommu/intel/iommu.c                 | 10 +++-----
 drivers/iommu/iommu.c                       | 28 +++++++++++++++++++++
 drivers/iommu/ipmmu-vmsa.c                  |  4 +--
 drivers/iommu/omap-iommu.c                  |  3 +--
 drivers/iommu/s390-iommu.c                  |  2 +-
 drivers/iommu/sprd-iommu.c                  |  6 ++---
 drivers/iommu/tegra-gart.c                  |  2 +-
 drivers/iommu/virtio-iommu.c                |  3 +--
 13 files changed, 47 insertions(+), 46 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 840831d5d2ad..ad499658a6b6 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1662,7 +1662,7 @@ static int attach_device(struct device *dev,
 	if (domain->flags & PD_IOMMUV2_MASK) {
 		struct iommu_domain *def_domain = iommu_get_dma_domain(dev);
 
-		ret = -EINVAL;
+		ret = -EMEDIUMTYPE;
 		if (def_domain->type != IOMMU_DOMAIN_IDENTITY)
 			goto out;
 
diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 8af0242a90d9..e58dc310afd7 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -495,10 +495,10 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 
 	if (cfg->stream_maps[0].dart->force_bypass &&
 	    domain->type != IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 	if (!cfg->stream_maps[0].dart->supports_bypass &&
 	    domain->type == IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 
 	ret = apple_dart_finalize_domain(domain, cfg);
 	if (ret)
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 88817a3376ef..5b64138f549d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2420,24 +2420,15 @@ 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 = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		goto out_unlock;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 2ed3594f384e..4b95673be076 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1167,10 +1167,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 		goto rpm_put;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 4c077c38fbd6..8372f985c14a 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));
-		return -EINVAL;
-	}
+	if (qcom_domain->iommu != qcom_iommu)
+		return -EMEDIUMTYPE;
 
 	return 0;
 }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 44016594831d..db5fb799e350 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4323,19 +4323,15 @@ 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 -EMEDIUMTYPE;
 
 	/* 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 -EMEDIUMTYPE;
 	dmar_domain->gaw = addr_width;
 
 	/*
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..5b0afe39275e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1972,6 +1972,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2098,6 +2112,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	int ret;
diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 8fdb84b3642b..82d63394b166 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -628,9 +628,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 	} 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 d9cf2820c02e..6bc8925726bf 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1471,8 +1471,7 @@ 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 = -EMEDIUMTYPE;
 		goto out;
 	}
 
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c898bcbbce11..ddcb78b284bb 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -127,7 +127,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 	/* Allow only devices with identical DMA range limits */
 	} else if (domain->geometry.aperture_start != zdev->start_dma ||
 		   domain->geometry.aperture_end != zdev->end_dma) {
-		rc = -EINVAL;
+		rc = -EMEDIUMTYPE;
 		spin_unlock_irqrestore(&s390_domain->list_lock, flags);
 		goto out_restore;
 	}
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index bd409bab6286..f6ae230ca1cd 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");
-		return -EINVAL;
-	}
+	if (dom->sdev)
+		return -EMEDIUMTYPE;
 
 	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 a6700a40a6f8..011c33e6ae31 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 = -EMEDIUMTYPE;
 	} 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 25be4b822aa0..a41a62dccb4d 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 = -EMEDIUMTYPE;
 	}
 	mutex_unlock(&vdomain->mutex);
 
-- 
2.17.1

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

[PATCH v5 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

[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 from the IOMMU driver during attach that the
reason attached failed is because of domain incompatability. EMEDIUMTYPE
is chosen because it is never used within the iommu subsystem today and
evokes a sense that the 'medium' aka the domain is incompatible.

VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are
related to domain incompatability. Also remove adjacent error prints for
these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is
clear enough to indicate an incompatability error.

Add kdocs describing this behavior.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/amd/iommu.c                   |  2 +-
 drivers/iommu/apple-dart.c                  |  4 +--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++--------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  5 +---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-----
 drivers/iommu/intel/iommu.c                 | 10 +++-----
 drivers/iommu/iommu.c                       | 28 +++++++++++++++++++++
 drivers/iommu/ipmmu-vmsa.c                  |  4 +--
 drivers/iommu/omap-iommu.c                  |  3 +--
 drivers/iommu/s390-iommu.c                  |  2 +-
 drivers/iommu/sprd-iommu.c                  |  6 ++---
 drivers/iommu/tegra-gart.c                  |  2 +-
 drivers/iommu/virtio-iommu.c                |  3 +--
 13 files changed, 47 insertions(+), 46 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 840831d5d2ad..ad499658a6b6 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1662,7 +1662,7 @@ static int attach_device(struct device *dev,
 	if (domain->flags & PD_IOMMUV2_MASK) {
 		struct iommu_domain *def_domain = iommu_get_dma_domain(dev);
 
-		ret = -EINVAL;
+		ret = -EMEDIUMTYPE;
 		if (def_domain->type != IOMMU_DOMAIN_IDENTITY)
 			goto out;
 
diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 8af0242a90d9..e58dc310afd7 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -495,10 +495,10 @@ static int apple_dart_attach_dev(struct iommu_domain *domain,
 
 	if (cfg->stream_maps[0].dart->force_bypass &&
 	    domain->type != IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 	if (!cfg->stream_maps[0].dart->supports_bypass &&
 	    domain->type == IOMMU_DOMAIN_IDENTITY)
-		return -EINVAL;
+		return -EMEDIUMTYPE;
 
 	ret = apple_dart_finalize_domain(domain, cfg);
 	if (ret)
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 88817a3376ef..5b64138f549d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2420,24 +2420,15 @@ 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 = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		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;
+		ret = -EMEDIUMTYPE;
 		goto out_unlock;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 2ed3594f384e..4b95673be076 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1167,10 +1167,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 		goto rpm_put;
 	}
 
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 4c077c38fbd6..8372f985c14a 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));
-		return -EINVAL;
-	}
+	if (qcom_domain->iommu != qcom_iommu)
+		return -EMEDIUMTYPE;
 
 	return 0;
 }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 44016594831d..db5fb799e350 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4323,19 +4323,15 @@ 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 -EMEDIUMTYPE;
 
 	/* 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 -EMEDIUMTYPE;
 	dmar_domain->gaw = addr_width;
 
 	/*
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..5b0afe39275e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1972,6 +1972,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2098,6 +2112,20 @@ 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
+ *
+ * Specifically, -EMEDIUMTYPE is returned as a soft failure if the domain and
+ * the device are incompatible in some way. This indicates that a caller should
+ * try another existing IOMMU domain or allocate a new one. And note that it's
+ * recommended to keep kernel print free when reporting -EMEDIUMTYPE error, as
+ * this function can be called to test compatibility with domains that will fail
+ * the test, which will result in a kernel log spam.
+ */
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 {
 	int ret;
diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 8fdb84b3642b..82d63394b166 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -628,9 +628,7 @@ 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;
+		ret = -EMEDIUMTYPE;
 	} 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 d9cf2820c02e..6bc8925726bf 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1471,8 +1471,7 @@ 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 = -EMEDIUMTYPE;
 		goto out;
 	}
 
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c898bcbbce11..ddcb78b284bb 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -127,7 +127,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 	/* Allow only devices with identical DMA range limits */
 	} else if (domain->geometry.aperture_start != zdev->start_dma ||
 		   domain->geometry.aperture_end != zdev->end_dma) {
-		rc = -EINVAL;
+		rc = -EMEDIUMTYPE;
 		spin_unlock_irqrestore(&s390_domain->list_lock, flags);
 		goto out_restore;
 	}
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index bd409bab6286..f6ae230ca1cd 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");
-		return -EINVAL;
-	}
+	if (dom->sdev)
+		return -EMEDIUMTYPE;
 
 	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 a6700a40a6f8..011c33e6ae31 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 = -EMEDIUMTYPE;
 	} 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 25be4b822aa0..a41a62dccb4d 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 = -EMEDIUMTYPE;
 	}
 	mutex_unlock(&vdomain->mutex);
 
-- 
2.17.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 2/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency

[Nicolin Chen]

From: Jason Gunthorpe <jgg@nvidia.com>

The KVM mechanism for controlling wbinvd is based on OR of the coherency
property of all devices attached to a guest, no matter whether those
devices are attached to a single domain or multiple domains.

On the other hand, the benefit to using separate domains was that those
devices attached to domains supporting enforced cache coherency always
mapped with the attributes necessary to provide that feature, therefore
if a non-enforced domain was dropped, the associated group removal would
re-trigger an evaluation by KVM.

In practice however, the only known cases of such mixed domains included
an Intel IGD device behind an IOMMU lacking snoop control, where such
devices do not support hotplug, therefore this scenario lacks testing and
is not considered sufficiently relevant to support.

After all, KVM won't take advantage of trying to push a device that could
do enforced cache coherency to a dedicated domain vs re-using an existing
domain, which is non-coherent.

Simplify this code and eliminate the test. This removes the only logic
that needed to have a dummy domain attached prior to searching for a
matching domain and simplifies the next patches.

It's unclear whether we want to further optimize the Intel driver to
update the domain coherency after a device is detached from it, at
least not before KVM can be verified to handle such dynamics in related
emulation paths (wbinvd, vcpu load, write_cr0, ept, etc.). In reality
we don't see an usage requiring such optimization as the only device
which imposes such non-coherency is Intel GPU which even doesn't
support hotplug/hot remove.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c496b7d0b96f..7530f0d727e5 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2288,9 +2288,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	 * testing if they're on the same bus_type.
 	 */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops &&
-		    d->enforce_cache_coherency ==
-			    domain->enforce_cache_coherency) {
+		if (d->domain->ops == domain->domain->ops) {
 			iommu_detach_group(domain->domain, group->iommu_group);
 			if (!iommu_attach_group(d->domain,
 						group->iommu_group)) {
-- 
2.17.1

[PATCH v5 2/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency

[Nicolin Chen via iommu]

From: Jason Gunthorpe <jgg@nvidia.com>

The KVM mechanism for controlling wbinvd is based on OR of the coherency
property of all devices attached to a guest, no matter whether those
devices are attached to a single domain or multiple domains.

On the other hand, the benefit to using separate domains was that those
devices attached to domains supporting enforced cache coherency always
mapped with the attributes necessary to provide that feature, therefore
if a non-enforced domain was dropped, the associated group removal would
re-trigger an evaluation by KVM.

In practice however, the only known cases of such mixed domains included
an Intel IGD device behind an IOMMU lacking snoop control, where such
devices do not support hotplug, therefore this scenario lacks testing and
is not considered sufficiently relevant to support.

After all, KVM won't take advantage of trying to push a device that could
do enforced cache coherency to a dedicated domain vs re-using an existing
domain, which is non-coherent.

Simplify this code and eliminate the test. This removes the only logic
that needed to have a dummy domain attached prior to searching for a
matching domain and simplifies the next patches.

It's unclear whether we want to further optimize the Intel driver to
update the domain coherency after a device is detached from it, at
least not before KVM can be verified to handle such dynamics in related
emulation paths (wbinvd, vcpu load, write_cr0, ept, etc.). In reality
we don't see an usage requiring such optimization as the only device
which imposes such non-coherency is Intel GPU which even doesn't
support hotplug/hot remove.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c496b7d0b96f..7530f0d727e5 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2288,9 +2288,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	 * testing if they're on the same bus_type.
 	 */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops &&
-		    d->enforce_cache_coherency ==
-			    domain->enforce_cache_coherency) {
+		if (d->domain->ops == domain->domain->ops) {
 			iommu_detach_group(domain->domain, group->iommu_group);
 			if (!iommu_attach_group(d->domain,
 						group->iommu_group)) {
-- 
2.17.1

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

[PATCH v5 2/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency

[Nicolin Chen]

From: Jason Gunthorpe <jgg@nvidia.com>

The KVM mechanism for controlling wbinvd is based on OR of the coherency
property of all devices attached to a guest, no matter whether those
devices are attached to a single domain or multiple domains.

On the other hand, the benefit to using separate domains was that those
devices attached to domains supporting enforced cache coherency always
mapped with the attributes necessary to provide that feature, therefore
if a non-enforced domain was dropped, the associated group removal would
re-trigger an evaluation by KVM.

In practice however, the only known cases of such mixed domains included
an Intel IGD device behind an IOMMU lacking snoop control, where such
devices do not support hotplug, therefore this scenario lacks testing and
is not considered sufficiently relevant to support.

After all, KVM won't take advantage of trying to push a device that could
do enforced cache coherency to a dedicated domain vs re-using an existing
domain, which is non-coherent.

Simplify this code and eliminate the test. This removes the only logic
that needed to have a dummy domain attached prior to searching for a
matching domain and simplifies the next patches.

It's unclear whether we want to further optimize the Intel driver to
update the domain coherency after a device is detached from it, at
least not before KVM can be verified to handle such dynamics in related
emulation paths (wbinvd, vcpu load, write_cr0, ept, etc.). In reality
we don't see an usage requiring such optimization as the only device
which imposes such non-coherency is Intel GPU which even doesn't
support hotplug/hot remove.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c496b7d0b96f..7530f0d727e5 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2288,9 +2288,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	 * testing if they're on the same bus_type.
 	 */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops &&
-		    d->enforce_cache_coherency ==
-			    domain->enforce_cache_coherency) {
+		if (d->domain->ops == domain->domain->ops) {
 			iommu_detach_group(domain->domain, group->iommu_group);
 			if (!iommu_attach_group(d->domain,
 						group->iommu_group)) {
-- 
2.17.1


_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Nicolin Chen]

The domain->ops validation was added, as a precaution, for mixed-driver
systems.

Per Robin's remarks,
* While bus_set_iommu() still exists, the core code prevents multiple
  drivers from registering, so we can't really run into a situation of
  having a mixed-driver system:
  https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/

* And there's plenty more significant problems than this to fix; in future
  when many can be permitted, we will rely on the IOMMU core code to check
  the domain->ops:
  https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/

So remove the check in VFIO for simplicity.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 7530f0d727e5..5992ee2345a0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2280,29 +2280,19 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 			domain->domain->ops->enforce_cache_coherency(
 				domain->domain);
 
-	/*
-	 * Try to match an existing compatible domain.  We don't want to
-	 * preclude an IOMMU driver supporting multiple bus_types and being
-	 * able to include different bus_types in the same IOMMU domain, so
-	 * we test whether the domains use the same iommu_ops rather than
-	 * testing if they're on the same bus_type.
-	 */
+	/* Try to match an existing compatible domain */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops) {
-			iommu_detach_group(domain->domain, group->iommu_group);
-			if (!iommu_attach_group(d->domain,
-						group->iommu_group)) {
-				list_add(&group->next, &d->group_list);
-				iommu_domain_free(domain->domain);
-				kfree(domain);
-				goto done;
-			}
-
-			ret = iommu_attach_group(domain->domain,
-						 group->iommu_group);
-			if (ret)
-				goto out_domain;
+		iommu_detach_group(domain->domain, group->iommu_group);
+		if (!iommu_attach_group(d->domain, group->iommu_group)) {
+			list_add(&group->next, &d->group_list);
+			iommu_domain_free(domain->domain);
+			kfree(domain);
+			goto done;
 		}
+
+		ret = iommu_attach_group(domain->domain,  group->iommu_group);
+		if (ret)
+			goto out_domain;
 	}
 
 	vfio_test_domain_fgsp(domain);
-- 
2.17.1

[PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Nicolin Chen via iommu]

The domain->ops validation was added, as a precaution, for mixed-driver
systems.

Per Robin's remarks,
* While bus_set_iommu() still exists, the core code prevents multiple
  drivers from registering, so we can't really run into a situation of
  having a mixed-driver system:
  https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/

* And there's plenty more significant problems than this to fix; in future
  when many can be permitted, we will rely on the IOMMU core code to check
  the domain->ops:
  https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/

So remove the check in VFIO for simplicity.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 7530f0d727e5..5992ee2345a0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2280,29 +2280,19 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 			domain->domain->ops->enforce_cache_coherency(
 				domain->domain);
 
-	/*
-	 * Try to match an existing compatible domain.  We don't want to
-	 * preclude an IOMMU driver supporting multiple bus_types and being
-	 * able to include different bus_types in the same IOMMU domain, so
-	 * we test whether the domains use the same iommu_ops rather than
-	 * testing if they're on the same bus_type.
-	 */
+	/* Try to match an existing compatible domain */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops) {
-			iommu_detach_group(domain->domain, group->iommu_group);
-			if (!iommu_attach_group(d->domain,
-						group->iommu_group)) {
-				list_add(&group->next, &d->group_list);
-				iommu_domain_free(domain->domain);
-				kfree(domain);
-				goto done;
-			}
-
-			ret = iommu_attach_group(domain->domain,
-						 group->iommu_group);
-			if (ret)
-				goto out_domain;
+		iommu_detach_group(domain->domain, group->iommu_group);
+		if (!iommu_attach_group(d->domain, group->iommu_group)) {
+			list_add(&group->next, &d->group_list);
+			iommu_domain_free(domain->domain);
+			kfree(domain);
+			goto done;
 		}
+
+		ret = iommu_attach_group(domain->domain,  group->iommu_group);
+		if (ret)
+			goto out_domain;
 	}
 
 	vfio_test_domain_fgsp(domain);
-- 
2.17.1

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

[PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Nicolin Chen]

The domain->ops validation was added, as a precaution, for mixed-driver
systems.

Per Robin's remarks,
* While bus_set_iommu() still exists, the core code prevents multiple
  drivers from registering, so we can't really run into a situation of
  having a mixed-driver system:
  https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/

* And there's plenty more significant problems than this to fix; in future
  when many can be permitted, we will rely on the IOMMU core code to check
  the domain->ops:
  https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/

So remove the check in VFIO for simplicity.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 7530f0d727e5..5992ee2345a0 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2280,29 +2280,19 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 			domain->domain->ops->enforce_cache_coherency(
 				domain->domain);
 
-	/*
-	 * Try to match an existing compatible domain.  We don't want to
-	 * preclude an IOMMU driver supporting multiple bus_types and being
-	 * able to include different bus_types in the same IOMMU domain, so
-	 * we test whether the domains use the same iommu_ops rather than
-	 * testing if they're on the same bus_type.
-	 */
+	/* Try to match an existing compatible domain */
 	list_for_each_entry(d, &iommu->domain_list, next) {
-		if (d->domain->ops == domain->domain->ops) {
-			iommu_detach_group(domain->domain, group->iommu_group);
-			if (!iommu_attach_group(d->domain,
-						group->iommu_group)) {
-				list_add(&group->next, &d->group_list);
-				iommu_domain_free(domain->domain);
-				kfree(domain);
-				goto done;
-			}
-
-			ret = iommu_attach_group(domain->domain,
-						 group->iommu_group);
-			if (ret)
-				goto out_domain;
+		iommu_detach_group(domain->domain, group->iommu_group);
+		if (!iommu_attach_group(d->domain, group->iommu_group)) {
+			list_add(&group->next, &d->group_list);
+			iommu_domain_free(domain->domain);
+			kfree(domain);
+			goto done;
 		}
+
+		ret = iommu_attach_group(domain->domain,  group->iommu_group);
+		if (ret)
+			goto out_domain;
 	}
 
 	vfio_test_domain_fgsp(domain);
-- 
2.17.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group()

[Nicolin Chen]

All devices in emulated_iommu_groups have pinned_page_dirty_scope
set, so the update_dirty_scope in the first list_for_each_entry
is always false. Clean it up, and move the "if update_dirty_scope"
part from the detach_group_done routine to the domain_list part.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5992ee2345a0..5624bbf02ab7 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2456,14 +2456,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_domain *domain;
 	struct vfio_iommu_group *group;
-	bool update_dirty_scope = false;
 	LIST_HEAD(iova_copy);
 
 	mutex_lock(&iommu->lock);
 	list_for_each_entry(group, &iommu->emulated_iommu_groups, next) {
 		if (group->iommu_group != iommu_group)
 			continue;
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
 		kfree(group);
 
@@ -2472,7 +2470,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			WARN_ON(iommu->notifier.head);
 			vfio_iommu_unmap_unpin_all(iommu);
 		}
-		goto detach_group_done;
+		mutex_unlock(&iommu->lock);
+		return;
 	}
 
 	/*
@@ -2488,9 +2487,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			continue;
 
 		iommu_detach_group(domain->domain, group->iommu_group);
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
-		kfree(group);
 		/*
 		 * Group ownership provides privilege, if the group list is
 		 * empty, the domain goes away. If it's the last domain with
@@ -2513,6 +2510,16 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			vfio_iommu_aper_expand(iommu, &iova_copy);
 			vfio_update_pgsize_bitmap(iommu);
 		}
+		/*
+		 * Removal of a group without dirty tracking may allow
+		 * the iommu scope to be promoted.
+		 */
+		if (!group->pinned_page_dirty_scope) {
+			iommu->num_non_pinned_groups--;
+			if (iommu->dirty_page_tracking)
+				vfio_iommu_populate_bitmap_full(iommu);
+		}
+		kfree(group);
 		break;
 	}
 
@@ -2521,16 +2528,6 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	else
 		vfio_iommu_iova_free(&iova_copy);
 
-detach_group_done:
-	/*
-	 * Removal of a group without dirty tracking may allow the iommu scope
-	 * to be promoted.
-	 */
-	if (update_dirty_scope) {
-		iommu->num_non_pinned_groups--;
-		if (iommu->dirty_page_tracking)
-			vfio_iommu_populate_bitmap_full(iommu);
-	}
 	mutex_unlock(&iommu->lock);
 }
 
-- 
2.17.1

[PATCH v5 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group()

[Nicolin Chen via iommu]

All devices in emulated_iommu_groups have pinned_page_dirty_scope
set, so the update_dirty_scope in the first list_for_each_entry
is always false. Clean it up, and move the "if update_dirty_scope"
part from the detach_group_done routine to the domain_list part.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5992ee2345a0..5624bbf02ab7 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2456,14 +2456,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_domain *domain;
 	struct vfio_iommu_group *group;
-	bool update_dirty_scope = false;
 	LIST_HEAD(iova_copy);
 
 	mutex_lock(&iommu->lock);
 	list_for_each_entry(group, &iommu->emulated_iommu_groups, next) {
 		if (group->iommu_group != iommu_group)
 			continue;
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
 		kfree(group);
 
@@ -2472,7 +2470,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			WARN_ON(iommu->notifier.head);
 			vfio_iommu_unmap_unpin_all(iommu);
 		}
-		goto detach_group_done;
+		mutex_unlock(&iommu->lock);
+		return;
 	}
 
 	/*
@@ -2488,9 +2487,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			continue;
 
 		iommu_detach_group(domain->domain, group->iommu_group);
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
-		kfree(group);
 		/*
 		 * Group ownership provides privilege, if the group list is
 		 * empty, the domain goes away. If it's the last domain with
@@ -2513,6 +2510,16 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			vfio_iommu_aper_expand(iommu, &iova_copy);
 			vfio_update_pgsize_bitmap(iommu);
 		}
+		/*
+		 * Removal of a group without dirty tracking may allow
+		 * the iommu scope to be promoted.
+		 */
+		if (!group->pinned_page_dirty_scope) {
+			iommu->num_non_pinned_groups--;
+			if (iommu->dirty_page_tracking)
+				vfio_iommu_populate_bitmap_full(iommu);
+		}
+		kfree(group);
 		break;
 	}
 
@@ -2521,16 +2528,6 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	else
 		vfio_iommu_iova_free(&iova_copy);
 
-detach_group_done:
-	/*
-	 * Removal of a group without dirty tracking may allow the iommu scope
-	 * to be promoted.
-	 */
-	if (update_dirty_scope) {
-		iommu->num_non_pinned_groups--;
-		if (iommu->dirty_page_tracking)
-			vfio_iommu_populate_bitmap_full(iommu);
-	}
 	mutex_unlock(&iommu->lock);
 }
 
-- 
2.17.1

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

[PATCH v5 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group()

[Nicolin Chen]

All devices in emulated_iommu_groups have pinned_page_dirty_scope
set, so the update_dirty_scope in the first list_for_each_entry
is always false. Clean it up, and move the "if update_dirty_scope"
part from the detach_group_done routine to the domain_list part.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5992ee2345a0..5624bbf02ab7 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2456,14 +2456,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_domain *domain;
 	struct vfio_iommu_group *group;
-	bool update_dirty_scope = false;
 	LIST_HEAD(iova_copy);
 
 	mutex_lock(&iommu->lock);
 	list_for_each_entry(group, &iommu->emulated_iommu_groups, next) {
 		if (group->iommu_group != iommu_group)
 			continue;
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
 		kfree(group);
 
@@ -2472,7 +2470,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			WARN_ON(iommu->notifier.head);
 			vfio_iommu_unmap_unpin_all(iommu);
 		}
-		goto detach_group_done;
+		mutex_unlock(&iommu->lock);
+		return;
 	}
 
 	/*
@@ -2488,9 +2487,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			continue;
 
 		iommu_detach_group(domain->domain, group->iommu_group);
-		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
-		kfree(group);
 		/*
 		 * Group ownership provides privilege, if the group list is
 		 * empty, the domain goes away. If it's the last domain with
@@ -2513,6 +2510,16 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			vfio_iommu_aper_expand(iommu, &iova_copy);
 			vfio_update_pgsize_bitmap(iommu);
 		}
+		/*
+		 * Removal of a group without dirty tracking may allow
+		 * the iommu scope to be promoted.
+		 */
+		if (!group->pinned_page_dirty_scope) {
+			iommu->num_non_pinned_groups--;
+			if (iommu->dirty_page_tracking)
+				vfio_iommu_populate_bitmap_full(iommu);
+		}
+		kfree(group);
 		break;
 	}
 
@@ -2521,16 +2528,6 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	else
 		vfio_iommu_iova_free(&iova_copy);
 
-detach_group_done:
-	/*
-	 * Removal of a group without dirty tracking may allow the iommu scope
-	 * to be promoted.
-	 */
-	if (update_dirty_scope) {
-		iommu->num_non_pinned_groups--;
-		if (iommu->dirty_page_tracking)
-			vfio_iommu_populate_bitmap_full(iommu);
-	}
 	mutex_unlock(&iommu->lock);
 }
 
-- 
2.17.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 5/5] vfio/iommu_type1: Simplify group attachment

[Nicolin Chen]

Un-inline the domain specific logic from the attach/detach_group ops into
two paired functions vfio_iommu_alloc_attach_domain() and
vfio_iommu_detach_destroy_domain() that strictly deal with creating and
destroying struct vfio_domains.

Add the logic to check for EMEDIUMTYPE return code of iommu_attach_group()
and avoid the extra domain allocations and attach/detach sequences of the
old code. This allows properly detecting an actual attach error, like
-ENOMEM, vs treating all attach errors as an incompatible domain.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 333 +++++++++++++++++---------------
 1 file changed, 180 insertions(+), 153 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5624bbf02ab7..d3a4cedcd082 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2155,14 +2155,179 @@ static int vfio_iommu_domain_alloc(struct device *dev, void *data)
 	return 1; /* Don't iterate */
 }
 
+static struct vfio_domain *
+vfio_iommu_alloc_attach_domain(struct vfio_iommu *iommu,
+			       struct vfio_iommu_group *group,
+			       struct list_head *group_resv_regions)
+{
+	struct iommu_domain *new_domain;
+	struct vfio_domain *domain;
+	phys_addr_t resv_msi_base;
+	int ret = 0;
+
+	/* Try to match an existing compatible domain */
+	list_for_each_entry (domain, &iommu->domain_list, next) {
+		ret = iommu_attach_group(domain->domain, group->iommu_group);
+		/* -EMEDIUMTYPE means an incompatible domain, so try next one */
+		if (ret == -EMEDIUMTYPE)
+			continue;
+		if (ret)
+			return ERR_PTR(ret);
+		goto done;
+	}
+
+	/*
+	 * Going via the iommu_group iterator avoids races, and trivially gives
+	 * us a representative device for the IOMMU API call. We don't actually
+	 * want to iterate beyond the first device (if any).
+	 */
+	iommu_group_for_each_dev(group->iommu_group, &new_domain,
+				 vfio_iommu_domain_alloc);
+	if (!new_domain)
+		return ERR_PTR(-EIO);
+
+	if (iommu->nesting) {
+		ret = iommu_enable_nesting(new_domain);
+		if (ret)
+			goto out_free_iommu_domain;
+	}
+
+	ret = iommu_attach_group(new_domain, group->iommu_group);
+	if (ret)
+		goto out_free_iommu_domain;
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain) {
+		ret = -ENOMEM;
+		goto out_detach;
+	}
+
+	domain->domain = new_domain;
+	vfio_test_domain_fgsp(domain);
+
+	/*
+	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
+	 * no-snoop set) then VFIO always turns this feature on because on Intel
+	 * platforms it optimizes KVM to disable wbinvd emulation.
+	 */
+	if (new_domain->ops->enforce_cache_coherency)
+		domain->enforce_cache_coherency =
+			new_domain->ops->enforce_cache_coherency(new_domain);
+
+	/* replay mappings on new domains */
+	ret = vfio_iommu_replay(iommu, domain);
+	if (ret)
+		goto out_free_domain;
+
+	if (vfio_iommu_has_sw_msi(group_resv_regions, &resv_msi_base)) {
+		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
+		if (ret && ret != -ENODEV)
+			goto out_free_domain;
+	}
+
+	INIT_LIST_HEAD(&domain->group_list);
+	list_add(&domain->next, &iommu->domain_list);
+	vfio_update_pgsize_bitmap(iommu);
+
+done:
+	list_add(&group->next, &domain->group_list);
+
+	/*
+	 * An iommu backed group can dirty memory directly and therefore
+	 * demotes the iommu scope until it declares itself dirty tracking
+	 * capable via the page pinning interface.
+	 */
+	iommu->num_non_pinned_groups++;
+
+	return domain;
+
+out_free_domain:
+	kfree(domain);
+out_detach:
+	iommu_detach_group(new_domain, group->iommu_group);
+out_free_iommu_domain:
+	iommu_domain_free(new_domain);
+	return ERR_PTR(ret);
+}
+
+static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
+{
+	struct rb_node *node;
+
+	while ((node = rb_first(&iommu->dma_list)))
+		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
+}
+
+static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
+{
+	struct rb_node *n, *p;
+
+	n = rb_first(&iommu->dma_list);
+	for (; n; n = rb_next(n)) {
+		struct vfio_dma *dma;
+		long locked = 0, unlocked = 0;
+
+		dma = rb_entry(n, struct vfio_dma, node);
+		unlocked += vfio_unmap_unpin(iommu, dma, false);
+		p = rb_first(&dma->pfn_list);
+		for (; p; p = rb_next(p)) {
+			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
+							 node);
+
+			if (!is_invalid_reserved_pfn(vpfn->pfn))
+				locked++;
+		}
+		vfio_lock_acct(dma, locked - unlocked, true);
+	}
+}
+
+static void vfio_iommu_detach_destroy_domain(struct vfio_domain *domain,
+					     struct vfio_iommu *iommu,
+					     struct vfio_iommu_group *group)
+{
+	iommu_detach_group(domain->domain, group->iommu_group);
+	list_del(&group->next);
+	if (!list_empty(&domain->group_list))
+		goto out_dirty;
+
+	/*
+	 * Group ownership provides privilege, if the group list is empty, the
+	 * domain goes away. If it's the last domain with iommu and external
+	 * domain doesn't exist, then all the mappings go away too. If it's the
+	 * last domain with iommu and external domain exist, update accounting
+	 */
+	if (list_is_singular(&iommu->domain_list)) {
+		if (list_empty(&iommu->emulated_iommu_groups)) {
+			WARN_ON(iommu->notifier.head);
+			vfio_iommu_unmap_unpin_all(iommu);
+		} else {
+			vfio_iommu_unmap_unpin_reaccount(iommu);
+		}
+	}
+	iommu_domain_free(domain->domain);
+	list_del(&domain->next);
+	kfree(domain);
+	vfio_update_pgsize_bitmap(iommu);
+
+out_dirty:
+	/*
+	 * Removal of a group without dirty tracking may allow the iommu scope
+	 * to be promoted.
+	 */
+	if (!group->pinned_page_dirty_scope) {
+		iommu->num_non_pinned_groups--;
+		if (iommu->dirty_page_tracking)
+			vfio_iommu_populate_bitmap_full(iommu);
+	}
+}
+
 static int vfio_iommu_type1_attach_group(void *iommu_data,
 		struct iommu_group *iommu_group, enum vfio_group_type type)
 {
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_iommu_group *group;
-	struct vfio_domain *domain, *d;
-	bool resv_msi, msi_remap;
-	phys_addr_t resv_msi_base = 0;
+	struct vfio_domain *domain;
+	bool msi_remap;
 	struct iommu_domain_geometry *geo;
 	LIST_HEAD(iova_copy);
 	LIST_HEAD(group_resv_regions);
@@ -2193,32 +2358,17 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_unlock;
 	}
 
-	ret = -ENOMEM;
-	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
-	if (!domain)
+	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
+	if (ret)
 		goto out_free_group;
 
-	/*
-	 * Going via the iommu_group iterator avoids races, and trivially gives
-	 * us a representative device for the IOMMU API call. We don't actually
-	 * want to iterate beyond the first device (if any).
-	 */
-	ret = -EIO;
-	iommu_group_for_each_dev(iommu_group, &domain->domain,
-				 vfio_iommu_domain_alloc);
-	if (!domain->domain)
-		goto out_free_domain;
-
-	if (iommu->nesting) {
-		ret = iommu_enable_nesting(domain->domain);
-		if (ret)
-			goto out_domain;
+	domain = vfio_iommu_alloc_attach_domain(iommu, group,
+						&group_resv_regions);
+	if (IS_ERR(domain)) {
+		ret = PTR_ERR(domain);
+		goto out_free_group;
 	}
 
-	ret = iommu_attach_group(domain->domain, group->iommu_group);
-	if (ret)
-		goto out_domain;
-
 	/* Get aperture info */
 	geo = &domain->domain->geometry;
 	if (vfio_iommu_aper_conflict(iommu, geo->aperture_start,
@@ -2227,10 +2377,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
-	if (ret)
-		goto out_detach;
-
 	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
 		ret = -EINVAL;
 		goto out_detach;
@@ -2254,11 +2400,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	if (ret)
 		goto out_detach;
 
-	resv_msi = vfio_iommu_has_sw_msi(&group_resv_regions, &resv_msi_base);
-
-	INIT_LIST_HEAD(&domain->group_list);
-	list_add(&group->next, &domain->group_list);
-
 	msi_remap = irq_domain_check_msi_remap() ||
 		    iommu_group_for_each_dev(iommu_group, (void *)IOMMU_CAP_INTR_REMAP,
 					     vfio_iommu_device_capable);
@@ -2270,107 +2411,25 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	/*
-	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
-	 * no-snoop set) then VFIO always turns this feature on because on Intel
-	 * platforms it optimizes KVM to disable wbinvd emulation.
-	 */
-	if (domain->domain->ops->enforce_cache_coherency)
-		domain->enforce_cache_coherency =
-			domain->domain->ops->enforce_cache_coherency(
-				domain->domain);
-
-	/* Try to match an existing compatible domain */
-	list_for_each_entry(d, &iommu->domain_list, next) {
-		iommu_detach_group(domain->domain, group->iommu_group);
-		if (!iommu_attach_group(d->domain, group->iommu_group)) {
-			list_add(&group->next, &d->group_list);
-			iommu_domain_free(domain->domain);
-			kfree(domain);
-			goto done;
-		}
-
-		ret = iommu_attach_group(domain->domain,  group->iommu_group);
-		if (ret)
-			goto out_domain;
-	}
-
-	vfio_test_domain_fgsp(domain);
-
-	/* replay mappings on new domains */
-	ret = vfio_iommu_replay(iommu, domain);
-	if (ret)
-		goto out_detach;
-
-	if (resv_msi) {
-		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
-		if (ret && ret != -ENODEV)
-			goto out_detach;
-	}
-
-	list_add(&domain->next, &iommu->domain_list);
-	vfio_update_pgsize_bitmap(iommu);
-done:
 	/* Delete the old one and insert new iova list */
 	vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 
-	/*
-	 * An iommu backed group can dirty memory directly and therefore
-	 * demotes the iommu scope until it declares itself dirty tracking
-	 * capable via the page pinning interface.
-	 */
-	iommu->num_non_pinned_groups++;
 	mutex_unlock(&iommu->lock);
 	vfio_iommu_resv_free(&group_resv_regions);
 
 	return 0;
 
 out_detach:
-	iommu_detach_group(domain->domain, group->iommu_group);
-out_domain:
-	iommu_domain_free(domain->domain);
-	vfio_iommu_iova_free(&iova_copy);
-	vfio_iommu_resv_free(&group_resv_regions);
-out_free_domain:
-	kfree(domain);
+	vfio_iommu_detach_destroy_domain(domain, iommu, group);
 out_free_group:
 	kfree(group);
 out_unlock:
 	mutex_unlock(&iommu->lock);
+	vfio_iommu_iova_free(&iova_copy);
+	vfio_iommu_resv_free(&group_resv_regions);
 	return ret;
 }
 
-static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
-{
-	struct rb_node *node;
-
-	while ((node = rb_first(&iommu->dma_list)))
-		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
-}
-
-static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
-{
-	struct rb_node *n, *p;
-
-	n = rb_first(&iommu->dma_list);
-	for (; n; n = rb_next(n)) {
-		struct vfio_dma *dma;
-		long locked = 0, unlocked = 0;
-
-		dma = rb_entry(n, struct vfio_dma, node);
-		unlocked += vfio_unmap_unpin(iommu, dma, false);
-		p = rb_first(&dma->pfn_list);
-		for (; p; p = rb_next(p)) {
-			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
-							 node);
-
-			if (!is_invalid_reserved_pfn(vpfn->pfn))
-				locked++;
-		}
-		vfio_lock_acct(dma, locked - unlocked, true);
-	}
-}
-
 /*
  * Called when a domain is removed in detach. It is possible that
  * the removed domain decided the iova aperture window. Modify the
@@ -2485,44 +2544,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		group = find_iommu_group(domain, iommu_group);
 		if (!group)
 			continue;
-
-		iommu_detach_group(domain->domain, group->iommu_group);
-		list_del(&group->next);
-		/*
-		 * Group ownership provides privilege, if the group list is
-		 * empty, the domain goes away. If it's the last domain with
-		 * iommu and external domain doesn't exist, then all the
-		 * mappings go away too. If it's the last domain with iommu and
-		 * external domain exist, update accounting
-		 */
-		if (list_empty(&domain->group_list)) {
-			if (list_is_singular(&iommu->domain_list)) {
-				if (list_empty(&iommu->emulated_iommu_groups)) {
-					WARN_ON(iommu->notifier.head);
-					vfio_iommu_unmap_unpin_all(iommu);
-				} else {
-					vfio_iommu_unmap_unpin_reaccount(iommu);
-				}
-			}
-			iommu_domain_free(domain->domain);
-			list_del(&domain->next);
-			kfree(domain);
-			vfio_iommu_aper_expand(iommu, &iova_copy);
-			vfio_update_pgsize_bitmap(iommu);
-		}
-		/*
-		 * Removal of a group without dirty tracking may allow
-		 * the iommu scope to be promoted.
-		 */
-		if (!group->pinned_page_dirty_scope) {
-			iommu->num_non_pinned_groups--;
-			if (iommu->dirty_page_tracking)
-				vfio_iommu_populate_bitmap_full(iommu);
-		}
+		vfio_iommu_detach_destroy_domain(domain, iommu, group);
 		kfree(group);
 		break;
 	}
 
+	vfio_iommu_aper_expand(iommu, &iova_copy);
 	if (!vfio_iommu_resv_refresh(iommu, &iova_copy))
 		vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 	else
-- 
2.17.1

[PATCH v5 5/5] vfio/iommu_type1: Simplify group attachment

[Nicolin Chen via iommu]

Un-inline the domain specific logic from the attach/detach_group ops into
two paired functions vfio_iommu_alloc_attach_domain() and
vfio_iommu_detach_destroy_domain() that strictly deal with creating and
destroying struct vfio_domains.

Add the logic to check for EMEDIUMTYPE return code of iommu_attach_group()
and avoid the extra domain allocations and attach/detach sequences of the
old code. This allows properly detecting an actual attach error, like
-ENOMEM, vs treating all attach errors as an incompatible domain.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 333 +++++++++++++++++---------------
 1 file changed, 180 insertions(+), 153 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5624bbf02ab7..d3a4cedcd082 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2155,14 +2155,179 @@ static int vfio_iommu_domain_alloc(struct device *dev, void *data)
 	return 1; /* Don't iterate */
 }
 
+static struct vfio_domain *
+vfio_iommu_alloc_attach_domain(struct vfio_iommu *iommu,
+			       struct vfio_iommu_group *group,
+			       struct list_head *group_resv_regions)
+{
+	struct iommu_domain *new_domain;
+	struct vfio_domain *domain;
+	phys_addr_t resv_msi_base;
+	int ret = 0;
+
+	/* Try to match an existing compatible domain */
+	list_for_each_entry (domain, &iommu->domain_list, next) {
+		ret = iommu_attach_group(domain->domain, group->iommu_group);
+		/* -EMEDIUMTYPE means an incompatible domain, so try next one */
+		if (ret == -EMEDIUMTYPE)
+			continue;
+		if (ret)
+			return ERR_PTR(ret);
+		goto done;
+	}
+
+	/*
+	 * Going via the iommu_group iterator avoids races, and trivially gives
+	 * us a representative device for the IOMMU API call. We don't actually
+	 * want to iterate beyond the first device (if any).
+	 */
+	iommu_group_for_each_dev(group->iommu_group, &new_domain,
+				 vfio_iommu_domain_alloc);
+	if (!new_domain)
+		return ERR_PTR(-EIO);
+
+	if (iommu->nesting) {
+		ret = iommu_enable_nesting(new_domain);
+		if (ret)
+			goto out_free_iommu_domain;
+	}
+
+	ret = iommu_attach_group(new_domain, group->iommu_group);
+	if (ret)
+		goto out_free_iommu_domain;
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain) {
+		ret = -ENOMEM;
+		goto out_detach;
+	}
+
+	domain->domain = new_domain;
+	vfio_test_domain_fgsp(domain);
+
+	/*
+	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
+	 * no-snoop set) then VFIO always turns this feature on because on Intel
+	 * platforms it optimizes KVM to disable wbinvd emulation.
+	 */
+	if (new_domain->ops->enforce_cache_coherency)
+		domain->enforce_cache_coherency =
+			new_domain->ops->enforce_cache_coherency(new_domain);
+
+	/* replay mappings on new domains */
+	ret = vfio_iommu_replay(iommu, domain);
+	if (ret)
+		goto out_free_domain;
+
+	if (vfio_iommu_has_sw_msi(group_resv_regions, &resv_msi_base)) {
+		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
+		if (ret && ret != -ENODEV)
+			goto out_free_domain;
+	}
+
+	INIT_LIST_HEAD(&domain->group_list);
+	list_add(&domain->next, &iommu->domain_list);
+	vfio_update_pgsize_bitmap(iommu);
+
+done:
+	list_add(&group->next, &domain->group_list);
+
+	/*
+	 * An iommu backed group can dirty memory directly and therefore
+	 * demotes the iommu scope until it declares itself dirty tracking
+	 * capable via the page pinning interface.
+	 */
+	iommu->num_non_pinned_groups++;
+
+	return domain;
+
+out_free_domain:
+	kfree(domain);
+out_detach:
+	iommu_detach_group(new_domain, group->iommu_group);
+out_free_iommu_domain:
+	iommu_domain_free(new_domain);
+	return ERR_PTR(ret);
+}
+
+static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
+{
+	struct rb_node *node;
+
+	while ((node = rb_first(&iommu->dma_list)))
+		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
+}
+
+static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
+{
+	struct rb_node *n, *p;
+
+	n = rb_first(&iommu->dma_list);
+	for (; n; n = rb_next(n)) {
+		struct vfio_dma *dma;
+		long locked = 0, unlocked = 0;
+
+		dma = rb_entry(n, struct vfio_dma, node);
+		unlocked += vfio_unmap_unpin(iommu, dma, false);
+		p = rb_first(&dma->pfn_list);
+		for (; p; p = rb_next(p)) {
+			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
+							 node);
+
+			if (!is_invalid_reserved_pfn(vpfn->pfn))
+				locked++;
+		}
+		vfio_lock_acct(dma, locked - unlocked, true);
+	}
+}
+
+static void vfio_iommu_detach_destroy_domain(struct vfio_domain *domain,
+					     struct vfio_iommu *iommu,
+					     struct vfio_iommu_group *group)
+{
+	iommu_detach_group(domain->domain, group->iommu_group);
+	list_del(&group->next);
+	if (!list_empty(&domain->group_list))
+		goto out_dirty;
+
+	/*
+	 * Group ownership provides privilege, if the group list is empty, the
+	 * domain goes away. If it's the last domain with iommu and external
+	 * domain doesn't exist, then all the mappings go away too. If it's the
+	 * last domain with iommu and external domain exist, update accounting
+	 */
+	if (list_is_singular(&iommu->domain_list)) {
+		if (list_empty(&iommu->emulated_iommu_groups)) {
+			WARN_ON(iommu->notifier.head);
+			vfio_iommu_unmap_unpin_all(iommu);
+		} else {
+			vfio_iommu_unmap_unpin_reaccount(iommu);
+		}
+	}
+	iommu_domain_free(domain->domain);
+	list_del(&domain->next);
+	kfree(domain);
+	vfio_update_pgsize_bitmap(iommu);
+
+out_dirty:
+	/*
+	 * Removal of a group without dirty tracking may allow the iommu scope
+	 * to be promoted.
+	 */
+	if (!group->pinned_page_dirty_scope) {
+		iommu->num_non_pinned_groups--;
+		if (iommu->dirty_page_tracking)
+			vfio_iommu_populate_bitmap_full(iommu);
+	}
+}
+
 static int vfio_iommu_type1_attach_group(void *iommu_data,
 		struct iommu_group *iommu_group, enum vfio_group_type type)
 {
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_iommu_group *group;
-	struct vfio_domain *domain, *d;
-	bool resv_msi, msi_remap;
-	phys_addr_t resv_msi_base = 0;
+	struct vfio_domain *domain;
+	bool msi_remap;
 	struct iommu_domain_geometry *geo;
 	LIST_HEAD(iova_copy);
 	LIST_HEAD(group_resv_regions);
@@ -2193,32 +2358,17 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_unlock;
 	}
 
-	ret = -ENOMEM;
-	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
-	if (!domain)
+	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
+	if (ret)
 		goto out_free_group;
 
-	/*
-	 * Going via the iommu_group iterator avoids races, and trivially gives
-	 * us a representative device for the IOMMU API call. We don't actually
-	 * want to iterate beyond the first device (if any).
-	 */
-	ret = -EIO;
-	iommu_group_for_each_dev(iommu_group, &domain->domain,
-				 vfio_iommu_domain_alloc);
-	if (!domain->domain)
-		goto out_free_domain;
-
-	if (iommu->nesting) {
-		ret = iommu_enable_nesting(domain->domain);
-		if (ret)
-			goto out_domain;
+	domain = vfio_iommu_alloc_attach_domain(iommu, group,
+						&group_resv_regions);
+	if (IS_ERR(domain)) {
+		ret = PTR_ERR(domain);
+		goto out_free_group;
 	}
 
-	ret = iommu_attach_group(domain->domain, group->iommu_group);
-	if (ret)
-		goto out_domain;
-
 	/* Get aperture info */
 	geo = &domain->domain->geometry;
 	if (vfio_iommu_aper_conflict(iommu, geo->aperture_start,
@@ -2227,10 +2377,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
-	if (ret)
-		goto out_detach;
-
 	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
 		ret = -EINVAL;
 		goto out_detach;
@@ -2254,11 +2400,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	if (ret)
 		goto out_detach;
 
-	resv_msi = vfio_iommu_has_sw_msi(&group_resv_regions, &resv_msi_base);
-
-	INIT_LIST_HEAD(&domain->group_list);
-	list_add(&group->next, &domain->group_list);
-
 	msi_remap = irq_domain_check_msi_remap() ||
 		    iommu_group_for_each_dev(iommu_group, (void *)IOMMU_CAP_INTR_REMAP,
 					     vfio_iommu_device_capable);
@@ -2270,107 +2411,25 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	/*
-	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
-	 * no-snoop set) then VFIO always turns this feature on because on Intel
-	 * platforms it optimizes KVM to disable wbinvd emulation.
-	 */
-	if (domain->domain->ops->enforce_cache_coherency)
-		domain->enforce_cache_coherency =
-			domain->domain->ops->enforce_cache_coherency(
-				domain->domain);
-
-	/* Try to match an existing compatible domain */
-	list_for_each_entry(d, &iommu->domain_list, next) {
-		iommu_detach_group(domain->domain, group->iommu_group);
-		if (!iommu_attach_group(d->domain, group->iommu_group)) {
-			list_add(&group->next, &d->group_list);
-			iommu_domain_free(domain->domain);
-			kfree(domain);
-			goto done;
-		}
-
-		ret = iommu_attach_group(domain->domain,  group->iommu_group);
-		if (ret)
-			goto out_domain;
-	}
-
-	vfio_test_domain_fgsp(domain);
-
-	/* replay mappings on new domains */
-	ret = vfio_iommu_replay(iommu, domain);
-	if (ret)
-		goto out_detach;
-
-	if (resv_msi) {
-		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
-		if (ret && ret != -ENODEV)
-			goto out_detach;
-	}
-
-	list_add(&domain->next, &iommu->domain_list);
-	vfio_update_pgsize_bitmap(iommu);
-done:
 	/* Delete the old one and insert new iova list */
 	vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 
-	/*
-	 * An iommu backed group can dirty memory directly and therefore
-	 * demotes the iommu scope until it declares itself dirty tracking
-	 * capable via the page pinning interface.
-	 */
-	iommu->num_non_pinned_groups++;
 	mutex_unlock(&iommu->lock);
 	vfio_iommu_resv_free(&group_resv_regions);
 
 	return 0;
 
 out_detach:
-	iommu_detach_group(domain->domain, group->iommu_group);
-out_domain:
-	iommu_domain_free(domain->domain);
-	vfio_iommu_iova_free(&iova_copy);
-	vfio_iommu_resv_free(&group_resv_regions);
-out_free_domain:
-	kfree(domain);
+	vfio_iommu_detach_destroy_domain(domain, iommu, group);
 out_free_group:
 	kfree(group);
 out_unlock:
 	mutex_unlock(&iommu->lock);
+	vfio_iommu_iova_free(&iova_copy);
+	vfio_iommu_resv_free(&group_resv_regions);
 	return ret;
 }
 
-static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
-{
-	struct rb_node *node;
-
-	while ((node = rb_first(&iommu->dma_list)))
-		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
-}
-
-static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
-{
-	struct rb_node *n, *p;
-
-	n = rb_first(&iommu->dma_list);
-	for (; n; n = rb_next(n)) {
-		struct vfio_dma *dma;
-		long locked = 0, unlocked = 0;
-
-		dma = rb_entry(n, struct vfio_dma, node);
-		unlocked += vfio_unmap_unpin(iommu, dma, false);
-		p = rb_first(&dma->pfn_list);
-		for (; p; p = rb_next(p)) {
-			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
-							 node);
-
-			if (!is_invalid_reserved_pfn(vpfn->pfn))
-				locked++;
-		}
-		vfio_lock_acct(dma, locked - unlocked, true);
-	}
-}
-
 /*
  * Called when a domain is removed in detach. It is possible that
  * the removed domain decided the iova aperture window. Modify the
@@ -2485,44 +2544,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		group = find_iommu_group(domain, iommu_group);
 		if (!group)
 			continue;
-
-		iommu_detach_group(domain->domain, group->iommu_group);
-		list_del(&group->next);
-		/*
-		 * Group ownership provides privilege, if the group list is
-		 * empty, the domain goes away. If it's the last domain with
-		 * iommu and external domain doesn't exist, then all the
-		 * mappings go away too. If it's the last domain with iommu and
-		 * external domain exist, update accounting
-		 */
-		if (list_empty(&domain->group_list)) {
-			if (list_is_singular(&iommu->domain_list)) {
-				if (list_empty(&iommu->emulated_iommu_groups)) {
-					WARN_ON(iommu->notifier.head);
-					vfio_iommu_unmap_unpin_all(iommu);
-				} else {
-					vfio_iommu_unmap_unpin_reaccount(iommu);
-				}
-			}
-			iommu_domain_free(domain->domain);
-			list_del(&domain->next);
-			kfree(domain);
-			vfio_iommu_aper_expand(iommu, &iova_copy);
-			vfio_update_pgsize_bitmap(iommu);
-		}
-		/*
-		 * Removal of a group without dirty tracking may allow
-		 * the iommu scope to be promoted.
-		 */
-		if (!group->pinned_page_dirty_scope) {
-			iommu->num_non_pinned_groups--;
-			if (iommu->dirty_page_tracking)
-				vfio_iommu_populate_bitmap_full(iommu);
-		}
+		vfio_iommu_detach_destroy_domain(domain, iommu, group);
 		kfree(group);
 		break;
 	}
 
+	vfio_iommu_aper_expand(iommu, &iova_copy);
 	if (!vfio_iommu_resv_refresh(iommu, &iova_copy))
 		vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 	else
-- 
2.17.1

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

[PATCH v5 5/5] vfio/iommu_type1: Simplify group attachment

[Nicolin Chen]

Un-inline the domain specific logic from the attach/detach_group ops into
two paired functions vfio_iommu_alloc_attach_domain() and
vfio_iommu_detach_destroy_domain() that strictly deal with creating and
destroying struct vfio_domains.

Add the logic to check for EMEDIUMTYPE return code of iommu_attach_group()
and avoid the extra domain allocations and attach/detach sequences of the
old code. This allows properly detecting an actual attach error, like
-ENOMEM, vs treating all attach errors as an incompatible domain.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 333 +++++++++++++++++---------------
 1 file changed, 180 insertions(+), 153 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5624bbf02ab7..d3a4cedcd082 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2155,14 +2155,179 @@ static int vfio_iommu_domain_alloc(struct device *dev, void *data)
 	return 1; /* Don't iterate */
 }
 
+static struct vfio_domain *
+vfio_iommu_alloc_attach_domain(struct vfio_iommu *iommu,
+			       struct vfio_iommu_group *group,
+			       struct list_head *group_resv_regions)
+{
+	struct iommu_domain *new_domain;
+	struct vfio_domain *domain;
+	phys_addr_t resv_msi_base;
+	int ret = 0;
+
+	/* Try to match an existing compatible domain */
+	list_for_each_entry (domain, &iommu->domain_list, next) {
+		ret = iommu_attach_group(domain->domain, group->iommu_group);
+		/* -EMEDIUMTYPE means an incompatible domain, so try next one */
+		if (ret == -EMEDIUMTYPE)
+			continue;
+		if (ret)
+			return ERR_PTR(ret);
+		goto done;
+	}
+
+	/*
+	 * Going via the iommu_group iterator avoids races, and trivially gives
+	 * us a representative device for the IOMMU API call. We don't actually
+	 * want to iterate beyond the first device (if any).
+	 */
+	iommu_group_for_each_dev(group->iommu_group, &new_domain,
+				 vfio_iommu_domain_alloc);
+	if (!new_domain)
+		return ERR_PTR(-EIO);
+
+	if (iommu->nesting) {
+		ret = iommu_enable_nesting(new_domain);
+		if (ret)
+			goto out_free_iommu_domain;
+	}
+
+	ret = iommu_attach_group(new_domain, group->iommu_group);
+	if (ret)
+		goto out_free_iommu_domain;
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain) {
+		ret = -ENOMEM;
+		goto out_detach;
+	}
+
+	domain->domain = new_domain;
+	vfio_test_domain_fgsp(domain);
+
+	/*
+	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
+	 * no-snoop set) then VFIO always turns this feature on because on Intel
+	 * platforms it optimizes KVM to disable wbinvd emulation.
+	 */
+	if (new_domain->ops->enforce_cache_coherency)
+		domain->enforce_cache_coherency =
+			new_domain->ops->enforce_cache_coherency(new_domain);
+
+	/* replay mappings on new domains */
+	ret = vfio_iommu_replay(iommu, domain);
+	if (ret)
+		goto out_free_domain;
+
+	if (vfio_iommu_has_sw_msi(group_resv_regions, &resv_msi_base)) {
+		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
+		if (ret && ret != -ENODEV)
+			goto out_free_domain;
+	}
+
+	INIT_LIST_HEAD(&domain->group_list);
+	list_add(&domain->next, &iommu->domain_list);
+	vfio_update_pgsize_bitmap(iommu);
+
+done:
+	list_add(&group->next, &domain->group_list);
+
+	/*
+	 * An iommu backed group can dirty memory directly and therefore
+	 * demotes the iommu scope until it declares itself dirty tracking
+	 * capable via the page pinning interface.
+	 */
+	iommu->num_non_pinned_groups++;
+
+	return domain;
+
+out_free_domain:
+	kfree(domain);
+out_detach:
+	iommu_detach_group(new_domain, group->iommu_group);
+out_free_iommu_domain:
+	iommu_domain_free(new_domain);
+	return ERR_PTR(ret);
+}
+
+static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
+{
+	struct rb_node *node;
+
+	while ((node = rb_first(&iommu->dma_list)))
+		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
+}
+
+static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
+{
+	struct rb_node *n, *p;
+
+	n = rb_first(&iommu->dma_list);
+	for (; n; n = rb_next(n)) {
+		struct vfio_dma *dma;
+		long locked = 0, unlocked = 0;
+
+		dma = rb_entry(n, struct vfio_dma, node);
+		unlocked += vfio_unmap_unpin(iommu, dma, false);
+		p = rb_first(&dma->pfn_list);
+		for (; p; p = rb_next(p)) {
+			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
+							 node);
+
+			if (!is_invalid_reserved_pfn(vpfn->pfn))
+				locked++;
+		}
+		vfio_lock_acct(dma, locked - unlocked, true);
+	}
+}
+
+static void vfio_iommu_detach_destroy_domain(struct vfio_domain *domain,
+					     struct vfio_iommu *iommu,
+					     struct vfio_iommu_group *group)
+{
+	iommu_detach_group(domain->domain, group->iommu_group);
+	list_del(&group->next);
+	if (!list_empty(&domain->group_list))
+		goto out_dirty;
+
+	/*
+	 * Group ownership provides privilege, if the group list is empty, the
+	 * domain goes away. If it's the last domain with iommu and external
+	 * domain doesn't exist, then all the mappings go away too. If it's the
+	 * last domain with iommu and external domain exist, update accounting
+	 */
+	if (list_is_singular(&iommu->domain_list)) {
+		if (list_empty(&iommu->emulated_iommu_groups)) {
+			WARN_ON(iommu->notifier.head);
+			vfio_iommu_unmap_unpin_all(iommu);
+		} else {
+			vfio_iommu_unmap_unpin_reaccount(iommu);
+		}
+	}
+	iommu_domain_free(domain->domain);
+	list_del(&domain->next);
+	kfree(domain);
+	vfio_update_pgsize_bitmap(iommu);
+
+out_dirty:
+	/*
+	 * Removal of a group without dirty tracking may allow the iommu scope
+	 * to be promoted.
+	 */
+	if (!group->pinned_page_dirty_scope) {
+		iommu->num_non_pinned_groups--;
+		if (iommu->dirty_page_tracking)
+			vfio_iommu_populate_bitmap_full(iommu);
+	}
+}
+
 static int vfio_iommu_type1_attach_group(void *iommu_data,
 		struct iommu_group *iommu_group, enum vfio_group_type type)
 {
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_iommu_group *group;
-	struct vfio_domain *domain, *d;
-	bool resv_msi, msi_remap;
-	phys_addr_t resv_msi_base = 0;
+	struct vfio_domain *domain;
+	bool msi_remap;
 	struct iommu_domain_geometry *geo;
 	LIST_HEAD(iova_copy);
 	LIST_HEAD(group_resv_regions);
@@ -2193,32 +2358,17 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_unlock;
 	}
 
-	ret = -ENOMEM;
-	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
-	if (!domain)
+	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
+	if (ret)
 		goto out_free_group;
 
-	/*
-	 * Going via the iommu_group iterator avoids races, and trivially gives
-	 * us a representative device for the IOMMU API call. We don't actually
-	 * want to iterate beyond the first device (if any).
-	 */
-	ret = -EIO;
-	iommu_group_for_each_dev(iommu_group, &domain->domain,
-				 vfio_iommu_domain_alloc);
-	if (!domain->domain)
-		goto out_free_domain;
-
-	if (iommu->nesting) {
-		ret = iommu_enable_nesting(domain->domain);
-		if (ret)
-			goto out_domain;
+	domain = vfio_iommu_alloc_attach_domain(iommu, group,
+						&group_resv_regions);
+	if (IS_ERR(domain)) {
+		ret = PTR_ERR(domain);
+		goto out_free_group;
 	}
 
-	ret = iommu_attach_group(domain->domain, group->iommu_group);
-	if (ret)
-		goto out_domain;
-
 	/* Get aperture info */
 	geo = &domain->domain->geometry;
 	if (vfio_iommu_aper_conflict(iommu, geo->aperture_start,
@@ -2227,10 +2377,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
-	if (ret)
-		goto out_detach;
-
 	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
 		ret = -EINVAL;
 		goto out_detach;
@@ -2254,11 +2400,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 	if (ret)
 		goto out_detach;
 
-	resv_msi = vfio_iommu_has_sw_msi(&group_resv_regions, &resv_msi_base);
-
-	INIT_LIST_HEAD(&domain->group_list);
-	list_add(&group->next, &domain->group_list);
-
 	msi_remap = irq_domain_check_msi_remap() ||
 		    iommu_group_for_each_dev(iommu_group, (void *)IOMMU_CAP_INTR_REMAP,
 					     vfio_iommu_device_capable);
@@ -2270,107 +2411,25 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 		goto out_detach;
 	}
 
-	/*
-	 * If the IOMMU can block non-coherent operations (ie PCIe TLPs with
-	 * no-snoop set) then VFIO always turns this feature on because on Intel
-	 * platforms it optimizes KVM to disable wbinvd emulation.
-	 */
-	if (domain->domain->ops->enforce_cache_coherency)
-		domain->enforce_cache_coherency =
-			domain->domain->ops->enforce_cache_coherency(
-				domain->domain);
-
-	/* Try to match an existing compatible domain */
-	list_for_each_entry(d, &iommu->domain_list, next) {
-		iommu_detach_group(domain->domain, group->iommu_group);
-		if (!iommu_attach_group(d->domain, group->iommu_group)) {
-			list_add(&group->next, &d->group_list);
-			iommu_domain_free(domain->domain);
-			kfree(domain);
-			goto done;
-		}
-
-		ret = iommu_attach_group(domain->domain,  group->iommu_group);
-		if (ret)
-			goto out_domain;
-	}
-
-	vfio_test_domain_fgsp(domain);
-
-	/* replay mappings on new domains */
-	ret = vfio_iommu_replay(iommu, domain);
-	if (ret)
-		goto out_detach;
-
-	if (resv_msi) {
-		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
-		if (ret && ret != -ENODEV)
-			goto out_detach;
-	}
-
-	list_add(&domain->next, &iommu->domain_list);
-	vfio_update_pgsize_bitmap(iommu);
-done:
 	/* Delete the old one and insert new iova list */
 	vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 
-	/*
-	 * An iommu backed group can dirty memory directly and therefore
-	 * demotes the iommu scope until it declares itself dirty tracking
-	 * capable via the page pinning interface.
-	 */
-	iommu->num_non_pinned_groups++;
 	mutex_unlock(&iommu->lock);
 	vfio_iommu_resv_free(&group_resv_regions);
 
 	return 0;
 
 out_detach:
-	iommu_detach_group(domain->domain, group->iommu_group);
-out_domain:
-	iommu_domain_free(domain->domain);
-	vfio_iommu_iova_free(&iova_copy);
-	vfio_iommu_resv_free(&group_resv_regions);
-out_free_domain:
-	kfree(domain);
+	vfio_iommu_detach_destroy_domain(domain, iommu, group);
 out_free_group:
 	kfree(group);
 out_unlock:
 	mutex_unlock(&iommu->lock);
+	vfio_iommu_iova_free(&iova_copy);
+	vfio_iommu_resv_free(&group_resv_regions);
 	return ret;
 }
 
-static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
-{
-	struct rb_node *node;
-
-	while ((node = rb_first(&iommu->dma_list)))
-		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
-}
-
-static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
-{
-	struct rb_node *n, *p;
-
-	n = rb_first(&iommu->dma_list);
-	for (; n; n = rb_next(n)) {
-		struct vfio_dma *dma;
-		long locked = 0, unlocked = 0;
-
-		dma = rb_entry(n, struct vfio_dma, node);
-		unlocked += vfio_unmap_unpin(iommu, dma, false);
-		p = rb_first(&dma->pfn_list);
-		for (; p; p = rb_next(p)) {
-			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
-							 node);
-
-			if (!is_invalid_reserved_pfn(vpfn->pfn))
-				locked++;
-		}
-		vfio_lock_acct(dma, locked - unlocked, true);
-	}
-}
-
 /*
  * Called when a domain is removed in detach. It is possible that
  * the removed domain decided the iova aperture window. Modify the
@@ -2485,44 +2544,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		group = find_iommu_group(domain, iommu_group);
 		if (!group)
 			continue;
-
-		iommu_detach_group(domain->domain, group->iommu_group);
-		list_del(&group->next);
-		/*
-		 * Group ownership provides privilege, if the group list is
-		 * empty, the domain goes away. If it's the last domain with
-		 * iommu and external domain doesn't exist, then all the
-		 * mappings go away too. If it's the last domain with iommu and
-		 * external domain exist, update accounting
-		 */
-		if (list_empty(&domain->group_list)) {
-			if (list_is_singular(&iommu->domain_list)) {
-				if (list_empty(&iommu->emulated_iommu_groups)) {
-					WARN_ON(iommu->notifier.head);
-					vfio_iommu_unmap_unpin_all(iommu);
-				} else {
-					vfio_iommu_unmap_unpin_reaccount(iommu);
-				}
-			}
-			iommu_domain_free(domain->domain);
-			list_del(&domain->next);
-			kfree(domain);
-			vfio_iommu_aper_expand(iommu, &iova_copy);
-			vfio_update_pgsize_bitmap(iommu);
-		}
-		/*
-		 * Removal of a group without dirty tracking may allow
-		 * the iommu scope to be promoted.
-		 */
-		if (!group->pinned_page_dirty_scope) {
-			iommu->num_non_pinned_groups--;
-			if (iommu->dirty_page_tracking)
-				vfio_iommu_populate_bitmap_full(iommu);
-		}
+		vfio_iommu_detach_destroy_domain(domain, iommu, group);
 		kfree(group);
 		break;
 	}
 
+	vfio_iommu_aper_expand(iommu, &iova_copy);
 	if (!vfio_iommu_resv_refresh(iommu, &iova_copy))
 		vfio_iommu_iova_insert_copy(iommu, &iova_copy);
 	else
-- 
2.17.1


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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Fri, 1 Jul 2022 14:44:50 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> This is a preparatory series for IOMMUFD v2 patches. It enforces error
> code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> an IOMMU domain and a device/group are incompatible. It also drops the
> useless domain->ops check since it won't fail in current environment.
> 
> These allow VFIO iommu code to simplify its group attachment routine, by
> avoiding the extra IOMMU domain allocations and attach/detach sequences
> of the old code.
> 
> Worths mentioning the exact match for enforce_cache_coherency is removed
> with this series, since there's very less value in doing that as KVM will
> not be able to take advantage of it -- this just wastes domain memory.
> Instead, we rely on Intel IOMMU driver taking care of that internally.
> 
> This is on github:
> https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

How do you foresee this going in, I'm imagining Joerg would merge the
first patch via the IOMMU tree and provide a topic branch that I'd
merge into the vfio tree along with the remaining patches.  Sound
right?  Thanks,

Alex

 
> Changelog
> v5:
>  * Rebased on top of Robin's "Simplify bus_type determination".
>  * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
>  * Added Baolu's "Reviewed-by".
> v4:
>  * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
>  * Added Baolu's and Kevin's Reviewed-by lines
> v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
>  * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
>  * Updated commit message of enforce_cache_coherency removing patch.
>  * Updated commit message of domain->ops removing patch.
>  * Replaced "goto out_unlock" with simply mutex_unlock() and return.
>  * Added a line of comments for -EMEDIUMTYPE return check.
>  * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
>    should be logically tied to the lifetime of a domain itself.
>  * Added Kevin's "Reviewed-by".
> v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
>  * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
>  * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
>  * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
>    since there's no mixed-driver use case that would fail the sanity.
>  * Updated commit log of the patch removing enforce_cache_coherency.
>  * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
>  * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
>    domain-reusing and new-domain pathways, like the code previously did.
>  * Fixed a typo in EMEDIUMTYPE patch.
> v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/
> 
> Jason Gunthorpe (1):
>   vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
>     coherency
> 
> Nicolin Chen (4):
>   iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
>   vfio/iommu_type1: Remove the domain->ops comparison
>   vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
>   vfio/iommu_type1: Simplify group attachment
> 
>  drivers/iommu/amd/iommu.c                   |   2 +-
>  drivers/iommu/apple-dart.c                  |   4 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
>  drivers/iommu/intel/iommu.c                 |  10 +-
>  drivers/iommu/iommu.c                       |  28 ++
>  drivers/iommu/ipmmu-vmsa.c                  |   4 +-
>  drivers/iommu/omap-iommu.c                  |   3 +-
>  drivers/iommu/s390-iommu.c                  |   2 +-
>  drivers/iommu/sprd-iommu.c                  |   6 +-
>  drivers/iommu/tegra-gart.c                  |   2 +-
>  drivers/iommu/virtio-iommu.c                |   3 +-
>  drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
>  14 files changed, 229 insertions(+), 216 deletions(-)
> 

Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Fri, 1 Jul 2022 14:44:50 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> This is a preparatory series for IOMMUFD v2 patches. It enforces error
> code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> an IOMMU domain and a device/group are incompatible. It also drops the
> useless domain->ops check since it won't fail in current environment.
> 
> These allow VFIO iommu code to simplify its group attachment routine, by
> avoiding the extra IOMMU domain allocations and attach/detach sequences
> of the old code.
> 
> Worths mentioning the exact match for enforce_cache_coherency is removed
> with this series, since there's very less value in doing that as KVM will
> not be able to take advantage of it -- this just wastes domain memory.
> Instead, we rely on Intel IOMMU driver taking care of that internally.
> 
> This is on github:
> https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

How do you foresee this going in, I'm imagining Joerg would merge the
first patch via the IOMMU tree and provide a topic branch that I'd
merge into the vfio tree along with the remaining patches.  Sound
right?  Thanks,

Alex

 
> Changelog
> v5:
>  * Rebased on top of Robin's "Simplify bus_type determination".
>  * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
>  * Added Baolu's "Reviewed-by".
> v4:
>  * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
>  * Added Baolu's and Kevin's Reviewed-by lines
> v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
>  * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
>  * Updated commit message of enforce_cache_coherency removing patch.
>  * Updated commit message of domain->ops removing patch.
>  * Replaced "goto out_unlock" with simply mutex_unlock() and return.
>  * Added a line of comments for -EMEDIUMTYPE return check.
>  * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
>    should be logically tied to the lifetime of a domain itself.
>  * Added Kevin's "Reviewed-by".
> v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
>  * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
>  * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
>  * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
>    since there's no mixed-driver use case that would fail the sanity.
>  * Updated commit log of the patch removing enforce_cache_coherency.
>  * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
>  * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
>    domain-reusing and new-domain pathways, like the code previously did.
>  * Fixed a typo in EMEDIUMTYPE patch.
> v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/
> 
> Jason Gunthorpe (1):
>   vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
>     coherency
> 
> Nicolin Chen (4):
>   iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
>   vfio/iommu_type1: Remove the domain->ops comparison
>   vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
>   vfio/iommu_type1: Simplify group attachment
> 
>  drivers/iommu/amd/iommu.c                   |   2 +-
>  drivers/iommu/apple-dart.c                  |   4 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
>  drivers/iommu/intel/iommu.c                 |  10 +-
>  drivers/iommu/iommu.c                       |  28 ++
>  drivers/iommu/ipmmu-vmsa.c                  |   4 +-
>  drivers/iommu/omap-iommu.c                  |   3 +-
>  drivers/iommu/s390-iommu.c                  |   2 +-
>  drivers/iommu/sprd-iommu.c                  |   6 +-
>  drivers/iommu/tegra-gart.c                  |   2 +-
>  drivers/iommu/virtio-iommu.c                |   3 +-
>  drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
>  14 files changed, 229 insertions(+), 216 deletions(-)
> 

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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Fri, 1 Jul 2022 14:44:50 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> This is a preparatory series for IOMMUFD v2 patches. It enforces error
> code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> an IOMMU domain and a device/group are incompatible. It also drops the
> useless domain->ops check since it won't fail in current environment.
> 
> These allow VFIO iommu code to simplify its group attachment routine, by
> avoiding the extra IOMMU domain allocations and attach/detach sequences
> of the old code.
> 
> Worths mentioning the exact match for enforce_cache_coherency is removed
> with this series, since there's very less value in doing that as KVM will
> not be able to take advantage of it -- this just wastes domain memory.
> Instead, we rely on Intel IOMMU driver taking care of that internally.
> 
> This is on github:
> https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

How do you foresee this going in, I'm imagining Joerg would merge the
first patch via the IOMMU tree and provide a topic branch that I'd
merge into the vfio tree along with the remaining patches.  Sound
right?  Thanks,

Alex

 
> Changelog
> v5:
>  * Rebased on top of Robin's "Simplify bus_type determination".
>  * Fixed a wrong change returning -EMEDIUMTYPE in arm-smmu driver.
>  * Added Baolu's "Reviewed-by".
> v4:
>  * Dropped -EMEDIUMTYPE change in mtk_v1 driver per Robin's input
>  * Added Baolu's and Kevin's Reviewed-by lines
> v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
>  * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
>  * Updated commit message of enforce_cache_coherency removing patch.
>  * Updated commit message of domain->ops removing patch.
>  * Replaced "goto out_unlock" with simply mutex_unlock() and return.
>  * Added a line of comments for -EMEDIUMTYPE return check.
>  * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
>    should be logically tied to the lifetime of a domain itself.
>  * Added Kevin's "Reviewed-by".
> v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@nvidia.com/
>  * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
>  * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
>  * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
>    since there's no mixed-driver use case that would fail the sanity.
>  * Updated commit log of the patch removing enforce_cache_coherency.
>  * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
>  * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
>    domain-reusing and new-domain pathways, like the code previously did.
>  * Fixed a typo in EMEDIUMTYPE patch.
> v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@nvidia.com/
> 
> Jason Gunthorpe (1):
>   vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
>     coherency
> 
> Nicolin Chen (4):
>   iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
>   vfio/iommu_type1: Remove the domain->ops comparison
>   vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
>   vfio/iommu_type1: Simplify group attachment
> 
>  drivers/iommu/amd/iommu.c                   |   2 +-
>  drivers/iommu/apple-dart.c                  |   4 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |   5 +-
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
>  drivers/iommu/intel/iommu.c                 |  10 +-
>  drivers/iommu/iommu.c                       |  28 ++
>  drivers/iommu/ipmmu-vmsa.c                  |   4 +-
>  drivers/iommu/omap-iommu.c                  |   3 +-
>  drivers/iommu/s390-iommu.c                  |   2 +-
>  drivers/iommu/sprd-iommu.c                  |   6 +-
>  drivers/iommu/tegra-gart.c                  |   2 +-
>  drivers/iommu/virtio-iommu.c                |   3 +-
>  drivers/vfio/vfio_iommu_type1.c             | 352 ++++++++++----------
>  14 files changed, 229 insertions(+), 216 deletions(-)
> 


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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:

> On Fri, 1 Jul 2022 14:44:50 -0700
> Nicolin Chen <nicolinc@nvidia.com> wrote:
> 
> > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > an IOMMU domain and a device/group are incompatible. It also drops the
> > useless domain->ops check since it won't fail in current environment.
> >
> > These allow VFIO iommu code to simplify its group attachment routine, by
> > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > of the old code.
> >
> > Worths mentioning the exact match for enforce_cache_coherency is removed
> > with this series, since there's very less value in doing that as KVM will
> > not be able to take advantage of it -- this just wastes domain memory.
> > Instead, we rely on Intel IOMMU driver taking care of that internally.
> >
> > This is on github:
> > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> 
> How do you foresee this going in, I'm imagining Joerg would merge the
> first patch via the IOMMU tree and provide a topic branch that I'd
> merge into the vfio tree along with the remaining patches.  Sound
> right?  Thanks,

We don't have any build dependency between the IOMMU change and
VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
failure now would be a hard failure without a chance falling back
to a new_domain, which is slightly different from the current flow.

For a potential existing use case that relies on reusing existing
domain, I think it'd be safer to have Joerg acking the first change
so you merge them all? Thank!

Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:

> On Fri, 1 Jul 2022 14:44:50 -0700
> Nicolin Chen <nicolinc@nvidia.com> wrote:
> 
> > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > an IOMMU domain and a device/group are incompatible. It also drops the
> > useless domain->ops check since it won't fail in current environment.
> >
> > These allow VFIO iommu code to simplify its group attachment routine, by
> > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > of the old code.
> >
> > Worths mentioning the exact match for enforce_cache_coherency is removed
> > with this series, since there's very less value in doing that as KVM will
> > not be able to take advantage of it -- this just wastes domain memory.
> > Instead, we rely on Intel IOMMU driver taking care of that internally.
> >
> > This is on github:
> > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> 
> How do you foresee this going in, I'm imagining Joerg would merge the
> first patch via the IOMMU tree and provide a topic branch that I'd
> merge into the vfio tree along with the remaining patches.  Sound
> right?  Thanks,

We don't have any build dependency between the IOMMU change and
VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
failure now would be a hard failure without a chance falling back
to a new_domain, which is slightly different from the current flow.

For a potential existing use case that relies on reusing existing
domain, I think it'd be safer to have Joerg acking the first change
so you merge them all? Thank!

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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Wed, 6 Jul 2022 10:53:52 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:
> 
> > On Fri, 1 Jul 2022 14:44:50 -0700
> > Nicolin Chen <nicolinc@nvidia.com> wrote:
> >   
> > > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > > an IOMMU domain and a device/group are incompatible. It also drops the
> > > useless domain->ops check since it won't fail in current environment.
> > >
> > > These allow VFIO iommu code to simplify its group attachment routine, by
> > > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > > of the old code.
> > >
> > > Worths mentioning the exact match for enforce_cache_coherency is removed
> > > with this series, since there's very less value in doing that as KVM will
> > > not be able to take advantage of it -- this just wastes domain memory.
> > > Instead, we rely on Intel IOMMU driver taking care of that internally.
> > >
> > > This is on github:
> > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach  
> > 
> > How do you foresee this going in, I'm imagining Joerg would merge the
> > first patch via the IOMMU tree and provide a topic branch that I'd
> > merge into the vfio tree along with the remaining patches.  Sound
> > right?  Thanks,  
> 
> We don't have any build dependency between the IOMMU change and
> VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> failure now would be a hard failure without a chance falling back
> to a new_domain, which is slightly different from the current flow.
> 
> For a potential existing use case that relies on reusing existing
> domain, I think it'd be safer to have Joerg acking the first change
> so you merge them all? Thank!

Works for me, I'll look for buy-in + ack from Joerg.  Thanks,

Alex

Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Wed, 6 Jul 2022 10:53:52 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:
> 
> > On Fri, 1 Jul 2022 14:44:50 -0700
> > Nicolin Chen <nicolinc@nvidia.com> wrote:
> >   
> > > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > > an IOMMU domain and a device/group are incompatible. It also drops the
> > > useless domain->ops check since it won't fail in current environment.
> > >
> > > These allow VFIO iommu code to simplify its group attachment routine, by
> > > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > > of the old code.
> > >
> > > Worths mentioning the exact match for enforce_cache_coherency is removed
> > > with this series, since there's very less value in doing that as KVM will
> > > not be able to take advantage of it -- this just wastes domain memory.
> > > Instead, we rely on Intel IOMMU driver taking care of that internally.
> > >
> > > This is on github:
> > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach  
> > 
> > How do you foresee this going in, I'm imagining Joerg would merge the
> > first patch via the IOMMU tree and provide a topic branch that I'd
> > merge into the vfio tree along with the remaining patches.  Sound
> > right?  Thanks,  
> 
> We don't have any build dependency between the IOMMU change and
> VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> failure now would be a hard failure without a chance falling back
> to a new_domain, which is slightly different from the current flow.
> 
> For a potential existing use case that relies on reusing existing
> domain, I think it'd be safer to have Joerg acking the first change
> so you merge them all? Thank!

Works for me, I'll look for buy-in + ack from Joerg.  Thanks,

Alex

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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Alex Williamson]

On Wed, 6 Jul 2022 10:53:52 -0700
Nicolin Chen <nicolinc@nvidia.com> wrote:

> On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:
> 
> > On Fri, 1 Jul 2022 14:44:50 -0700
> > Nicolin Chen <nicolinc@nvidia.com> wrote:
> >   
> > > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > > an IOMMU domain and a device/group are incompatible. It also drops the
> > > useless domain->ops check since it won't fail in current environment.
> > >
> > > These allow VFIO iommu code to simplify its group attachment routine, by
> > > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > > of the old code.
> > >
> > > Worths mentioning the exact match for enforce_cache_coherency is removed
> > > with this series, since there's very less value in doing that as KVM will
> > > not be able to take advantage of it -- this just wastes domain memory.
> > > Instead, we rely on Intel IOMMU driver taking care of that internally.
> > >
> > > This is on github:
> > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach  
> > 
> > How do you foresee this going in, I'm imagining Joerg would merge the
> > first patch via the IOMMU tree and provide a topic branch that I'd
> > merge into the vfio tree along with the remaining patches.  Sound
> > right?  Thanks,  
> 
> We don't have any build dependency between the IOMMU change and
> VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> failure now would be a hard failure without a chance falling back
> to a new_domain, which is slightly different from the current flow.
> 
> For a potential existing use case that relies on reusing existing
> domain, I think it'd be safer to have Joerg acking the first change
> so you merge them all? Thank!

Works for me, I'll look for buy-in + ack from Joerg.  Thanks,

Alex


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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 06, 2022 at 12:03:25PM -0600, Alex Williamson wrote:

> On Wed, 6 Jul 2022 10:53:52 -0700
> Nicolin Chen <nicolinc@nvidia.com> wrote:
> 
> > On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:
> >
> > > On Fri, 1 Jul 2022 14:44:50 -0700
> > > Nicolin Chen <nicolinc@nvidia.com> wrote:
> > >
> > > > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > > > an IOMMU domain and a device/group are incompatible. It also drops the
> > > > useless domain->ops check since it won't fail in current environment.
> > > >
> > > > These allow VFIO iommu code to simplify its group attachment routine, by
> > > > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > > > of the old code.
> > > >
> > > > Worths mentioning the exact match for enforce_cache_coherency is removed
> > > > with this series, since there's very less value in doing that as KVM will
> > > > not be able to take advantage of it -- this just wastes domain memory.
> > > > Instead, we rely on Intel IOMMU driver taking care of that internally.
> > > >
> > > > This is on github:
> > > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> > >
> > > How do you foresee this going in, I'm imagining Joerg would merge the
> > > first patch via the IOMMU tree and provide a topic branch that I'd
> > > merge into the vfio tree along with the remaining patches.  Sound
> > > right?  Thanks,
> >
> > We don't have any build dependency between the IOMMU change and
> > VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> > failure now would be a hard failure without a chance falling back
> > to a new_domain, which is slightly different from the current flow.
> >
> > For a potential existing use case that relies on reusing existing
> > domain, I think it'd be safer to have Joerg acking the first change
> > so you merge them all? Thank!
> 
> Works for me, I'll look for buy-in + ack from Joerg.  Thanks,
> 
> Alex

Joerg, would it be possible for you to ack at the IOMMU patch?

Thanks!
Nic

Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 06, 2022 at 12:03:25PM -0600, Alex Williamson wrote:

> On Wed, 6 Jul 2022 10:53:52 -0700
> Nicolin Chen <nicolinc@nvidia.com> wrote:
> 
> > On Wed, Jul 06, 2022 at 11:42:17AM -0600, Alex Williamson wrote:
> >
> > > On Fri, 1 Jul 2022 14:44:50 -0700
> > > Nicolin Chen <nicolinc@nvidia.com> wrote:
> > >
> > > > This is a preparatory series for IOMMUFD v2 patches. It enforces error
> > > > code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
> > > > an IOMMU domain and a device/group are incompatible. It also drops the
> > > > useless domain->ops check since it won't fail in current environment.
> > > >
> > > > These allow VFIO iommu code to simplify its group attachment routine, by
> > > > avoiding the extra IOMMU domain allocations and attach/detach sequences
> > > > of the old code.
> > > >
> > > > Worths mentioning the exact match for enforce_cache_coherency is removed
> > > > with this series, since there's very less value in doing that as KVM will
> > > > not be able to take advantage of it -- this just wastes domain memory.
> > > > Instead, we rely on Intel IOMMU driver taking care of that internally.
> > > >
> > > > This is on github:
> > > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> > >
> > > How do you foresee this going in, I'm imagining Joerg would merge the
> > > first patch via the IOMMU tree and provide a topic branch that I'd
> > > merge into the vfio tree along with the remaining patches.  Sound
> > > right?  Thanks,
> >
> > We don't have any build dependency between the IOMMU change and
> > VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> > failure now would be a hard failure without a chance falling back
> > to a new_domain, which is slightly different from the current flow.
> >
> > For a potential existing use case that relies on reusing existing
> > domain, I think it'd be safer to have Joerg acking the first change
> > so you merge them all? Thank!
> 
> Works for me, I'll look for buy-in + ack from Joerg.  Thanks,
> 
> Alex

Joerg, would it be possible for you to ack at the IOMMU patch?

Thanks!
Nic

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Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 13, 2022 at 04:57:36PM -0700, Nicolin Chen wrote:

> > > > > This is on github:
> > > > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> > > >
> > > > How do you foresee this going in, I'm imagining Joerg would merge the
> > > > first patch via the IOMMU tree and provide a topic branch that I'd
> > > > merge into the vfio tree along with the remaining patches.  Sound
> > > > right?  Thanks,
> > >
> > > We don't have any build dependency between the IOMMU change and
> > > VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> > > failure now would be a hard failure without a chance falling back
> > > to a new_domain, which is slightly different from the current flow.
> > >
> > > For a potential existing use case that relies on reusing existing
> > > domain, I think it'd be safer to have Joerg acking the first change
> > > so you merge them all? Thank!
> > 
> > Works for me, I'll look for buy-in + ack from Joerg.  Thanks,
> > 
> > Alex
> 
> Joerg, would it be possible for you to ack at the IOMMU patch?

Joerg, sorry for pinning again. Would it be possible for you
to give an ack at the IOMMU patch so that this series might
catch the last train of this cycle? Thanks!

Re: [PATCH v5 0/5] cover-letter: Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

On Wed, Jul 13, 2022 at 04:57:36PM -0700, Nicolin Chen wrote:

> > > > > This is on github:
> > > > > https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach
> > > >
> > > > How do you foresee this going in, I'm imagining Joerg would merge the
> > > > first patch via the IOMMU tree and provide a topic branch that I'd
> > > > merge into the vfio tree along with the remaining patches.  Sound
> > > > right?  Thanks,
> > >
> > > We don't have any build dependency between the IOMMU change and
> > > VFIO changes, yet, without the IOMMU one, any iommu_attach_group()
> > > failure now would be a hard failure without a chance falling back
> > > to a new_domain, which is slightly different from the current flow.
> > >
> > > For a potential existing use case that relies on reusing existing
> > > domain, I think it'd be safer to have Joerg acking the first change
> > > so you merge them all? Thank!
> > 
> > Works for me, I'll look for buy-in + ack from Joerg.  Thanks,
> > 
> > Alex
> 
> Joerg, would it be possible for you to ack at the IOMMU patch?

Joerg, sorry for pinning again. Would it be possible for you
to give an ack at the IOMMU patch so that this series might
catch the last train of this cycle? Thanks!

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Re: [PATCH v5 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:51PM -0700, Nicolin Chen wrote:
> 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 from the IOMMU driver during attach that the
> reason attached failed is because of domain incompatability. EMEDIUMTYPE
> is chosen because it is never used within the iommu subsystem today and
> evokes a sense that the 'medium' aka the domain is incompatible.
> 
> VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are
> related to domain incompatability. Also remove adjacent error prints for
> these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is
> clear enough to indicate an incompatability error.
> 
> Add kdocs describing this behavior.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/amd/iommu.c                   |  2 +-
>  drivers/iommu/apple-dart.c                  |  4 +--
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++--------
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |  5 +---
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-----
>  drivers/iommu/intel/iommu.c                 | 10 +++-----
>  drivers/iommu/iommu.c                       | 28 +++++++++++++++++++++
>  drivers/iommu/ipmmu-vmsa.c                  |  4 +--
>  drivers/iommu/omap-iommu.c                  |  3 +--
>  drivers/iommu/s390-iommu.c                  |  2 +-
>  drivers/iommu/sprd-iommu.c                  |  6 ++---
>  drivers/iommu/tegra-gart.c                  |  2 +-
>  drivers/iommu/virtio-iommu.c                |  3 +--
>  13 files changed, 47 insertions(+), 46 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH v5 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:51PM -0700, Nicolin Chen wrote:
> 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 from the IOMMU driver during attach that the
> reason attached failed is because of domain incompatability. EMEDIUMTYPE
> is chosen because it is never used within the iommu subsystem today and
> evokes a sense that the 'medium' aka the domain is incompatible.
> 
> VFIO can use this to know 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 all drivers to return EMEDIUMTYPE in their failure paths that are
> related to domain incompatability. Also remove adjacent error prints for
> these soft failures, to prevent a kernel log spam, since -EMEDIUMTYPE is
> clear enough to indicate an incompatability error.
> 
> Add kdocs describing this behavior.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/amd/iommu.c                   |  2 +-
>  drivers/iommu/apple-dart.c                  |  4 +--
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 +++--------
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |  5 +---
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-----
>  drivers/iommu/intel/iommu.c                 | 10 +++-----
>  drivers/iommu/iommu.c                       | 28 +++++++++++++++++++++
>  drivers/iommu/ipmmu-vmsa.c                  |  4 +--
>  drivers/iommu/omap-iommu.c                  |  3 +--
>  drivers/iommu/s390-iommu.c                  |  2 +-
>  drivers/iommu/sprd-iommu.c                  |  6 ++---
>  drivers/iommu/tegra-gart.c                  |  2 +-
>  drivers/iommu/virtio-iommu.c                |  3 +--
>  13 files changed, 47 insertions(+), 46 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

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Re: [PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:53PM -0700, Nicolin Chen wrote:
> The domain->ops validation was added, as a precaution, for mixed-driver
> systems.
> 
> Per Robin's remarks,
> * While bus_set_iommu() still exists, the core code prevents multiple
>   drivers from registering, so we can't really run into a situation of
>   having a mixed-driver system:
>   https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/
> 
> * And there's plenty more significant problems than this to fix; in future
>   when many can be permitted, we will rely on the IOMMU core code to check
>   the domain->ops:
>   https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/
> 
> So remove the check in VFIO for simplicity.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
>  1 file changed, 11 insertions(+), 21 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH v5 3/5] vfio/iommu_type1: Remove the domain->ops comparison

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:53PM -0700, Nicolin Chen wrote:
> The domain->ops validation was added, as a precaution, for mixed-driver
> systems.
> 
> Per Robin's remarks,
> * While bus_set_iommu() still exists, the core code prevents multiple
>   drivers from registering, so we can't really run into a situation of
>   having a mixed-driver system:
>   https://lore.kernel.org/kvm/6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com/
> 
> * And there's plenty more significant problems than this to fix; in future
>   when many can be permitted, we will rely on the IOMMU core code to check
>   the domain->ops:
>   https://lore.kernel.org/kvm/6575de6d-94ba-c427-5b1e-967750ddff23@arm.com/
> 
> So remove the check in VFIO for simplicity.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 32 +++++++++++---------------------
>  1 file changed, 11 insertions(+), 21 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

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Re: [PATCH v5 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group()

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:54PM -0700, Nicolin Chen wrote:
> All devices in emulated_iommu_groups have pinned_page_dirty_scope
> set, so the update_dirty_scope in the first list_for_each_entry
> is always false. Clean it up, and move the "if update_dirty_scope"
> part from the detach_group_done routine to the domain_list part.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 27 ++++++++++++---------------
>  1 file changed, 12 insertions(+), 15 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH v5 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group()

[Jason Gunthorpe]

On Fri, Jul 01, 2022 at 02:44:54PM -0700, Nicolin Chen wrote:
> All devices in emulated_iommu_groups have pinned_page_dirty_scope
> set, so the update_dirty_scope in the first list_for_each_entry
> is always false. Clean it up, and move the "if update_dirty_scope"
> part from the detach_group_done routine to the domain_list part.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 27 ++++++++++++---------------
>  1 file changed, 12 insertions(+), 15 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

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