[PATCH 04/14] iommufd: Use the iommufd_group to avoid duplicate reserved groups and msi setup

From: Jason Gunthorpe <jgg@nvidia.com>
To: iommu@lists.linux.dev, Kevin Tian <kevin.tian@intel.com>,
	linux-kselftest@vger.kernel.org
Cc: kvm@vger.kernel.org, Nicolin Chen <nicolinc@nvidia.com>,
	Yi Liu <yi.l.liu@intel.com>
Subject: [PATCH 04/14] iommufd: Use the iommufd_group to avoid duplicate reserved groups and msi setup
Date: Fri, 24 Feb 2023 20:27:49 -0400	[thread overview]
Message-ID: <4-v1-7612f88c19f5+2f21-iommufd_alloc_jgg@nvidia.com> (raw)
In-Reply-To: <0-v1-7612f88c19f5+2f21-iommufd_alloc_jgg@nvidia.com>

These items only needs to be done once per group, not once per device. The
once per device was a way to make the device list work. Since we are
abandoning this we can optimize things a bit.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommufd/device.c          | 38 ++++++++++++++-----------
 drivers/iommu/iommufd/io_pagetable.c    |  5 ++--
 drivers/iommu/iommufd/iommufd_private.h |  1 -
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 264bfa2212481f..75e8d79678736f 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -298,9 +298,20 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 		}
 	}
 
-	rc = iopt_table_enforce_group_resv_regions(&hwpt->ioas->iopt, idev->dev,
-						   idev->igroup->group,
-						   &sw_msi_start);
+	/*
+	 * The first device in the group to be attached will do all the work
+	 * to setup the hwpt and ioas. Every other device re-uses it through
+	 * the shared group attachment. Users are allowed/expected to attach
+	 * every device in the group to the same hwpt, that just turns into
+	 * a NOP.
+	 */
+	if (idev->igroup->devices) {
+		idev->igroup->devices++;
+		return 0;
+	}
+
+	rc = iopt_table_enforce_group_resv_regions(
+		&hwpt->ioas->iopt, idev->igroup->group, &sw_msi_start);
 	if (rc)
 		return rc;
 
@@ -308,22 +319,15 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 	if (rc)
 		goto err_unresv;
 
-	/*
-	 * Only attach to the group once for the first device that is in the
-	 * group. All the other devices will follow this attachment.
-	 * The user can attach every device individually as well.
-	 */
-	if (!idev->igroup->devices) {
-		rc = iommu_attach_group(hwpt->domain, idev->igroup->group);
-		if (rc)
-			goto err_unresv;
-		idev->igroup->hwpt = hwpt;
-		refcount_inc(&hwpt->obj.users);
-	}
+	rc = iommu_attach_group(hwpt->domain, idev->igroup->group);
+	if (rc)
+		goto err_unresv;
+	idev->igroup->hwpt = hwpt;
+	refcount_inc(&hwpt->obj.users);
 	idev->igroup->devices++;
 	return 0;
 err_unresv:
-	iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
+	iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->igroup->group);
 	return rc;
 }
 
@@ -339,7 +343,7 @@ iommufd_hw_pagetable_detach(struct iommufd_device *idev)
 		iommu_detach_group(hwpt->domain, idev->igroup->group);
 		idev->igroup->hwpt = NULL;
 	}
-	iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->dev);
+	iopt_remove_reserved_iova(&hwpt->ioas->iopt, idev->igroup->group);
 	return hwpt;
 }
 
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index e0ae72b9e67f86..096491bbb5acf5 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -1163,7 +1163,6 @@ void iopt_remove_access(struct io_pagetable *iopt,
 
 /* Narrow the valid_iova_itree to include reserved ranges from a group. */
 int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
-					  struct device *device,
 					  struct iommu_group *group,
 					  phys_addr_t *sw_msi_start)
 {
@@ -1191,7 +1190,7 @@ int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
 		}
 
 		rc = iopt_reserve_iova(iopt, resv->start,
-				       resv->length - 1 + resv->start, device);
+				       resv->length - 1 + resv->start, group);
 		if (rc)
 			goto out_reserved;
 	}
@@ -1206,7 +1205,7 @@ int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
 	goto out_free_resv;
 
 out_reserved:
-	__iopt_remove_reserved_iova(iopt, device);
+	__iopt_remove_reserved_iova(iopt, group);
 out_free_resv:
 	list_for_each_entry_safe(resv, tmp, &group_resv_regions, list)
 		kfree(resv);
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 5f3ad16da819e7..dbecdff013d082 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -77,7 +77,6 @@ int iopt_table_add_domain(struct io_pagetable *iopt,
 void iopt_table_remove_domain(struct io_pagetable *iopt,
 			      struct iommu_domain *domain);
 int iopt_table_enforce_group_resv_regions(struct io_pagetable *iopt,
-					  struct device *device,
 					  struct iommu_group *group,
 					  phys_addr_t *sw_msi_start);
 int iopt_set_allow_iova(struct io_pagetable *iopt,
-- 
2.39.1

