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From:   Nicolin Chen <nicolinc@nvidia.com>
To:     <jgg@nvidia.com>, <kevin.tian@intel.com>
CC:     <joro@8bytes.org>, <will@kernel.org>, <robin.murphy@arm.com>,
        <baolu.lu@linux.intel.com>, <iommu@lists.linux.dev>,
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Subject: [PATCH 1/2] iommufd/device: Drop enforce_cache_coherency in iommufd_device_do_replace
Date:   Fri, 20 Oct 2023 17:37:10 -0700
Message-ID: <5593200da9015fee7b2e8195c2998f36148d83de.1697848510.git.nicolinc@nvidia.com>
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According to the conversion in the following link:
https://lore.kernel.org/linux-iommu/20231020135501.GG3952@nvidia.com/

The enforce_cache_coherency should be set/enforced in the hwpt allocation
routine. The iommu driver in its attach_dev() op should decide whether to
reject or not a device that doesn't match with the configuration of cache
coherency. Drop the enforce_cache_coherency piece in replace(). Also move
the remaining "num_devices++" piece closer to the refcount that uses this
num_devices.

Cc: stable@vger.kernel.org
Fixes: e88d4ec154a8 ("iommufd: Add iommufd_device_replace()")
Suggested-by: Tian, Kevin <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/device.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index e88fa73a45e6..c93f3478f808 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -429,16 +429,6 @@ iommufd_device_do_replace(struct iommufd_device *idev,
 		return NULL;
 	}
 
-	/* Try to upgrade the domain we have */
-	list_for_each_entry(cur, &igroup->device_list, group_item) {
-		num_devices++;
-		if (cur->enforce_cache_coherency) {
-			rc = iommufd_hw_pagetable_enforce_cc(hwpt);
-			if (rc)
-				goto err_unlock;
-		}
-	}
-
 	old_hwpt = igroup->hwpt;
 	if (hwpt->ioas != old_hwpt->ioas) {
 		list_for_each_entry(cur, &igroup->device_list, group_item) {
@@ -465,6 +455,8 @@ iommufd_device_do_replace(struct iommufd_device *idev,
 
 	igroup->hwpt = hwpt;
 
+	list_for_each_entry(cur, &igroup->device_list, group_item)
+		num_devices++;
 	/*
 	 * Move the refcounts held by the device_list to the new hwpt. Retain a
 	 * refcount for this thread as the caller will free it.
-- 
2.42.0