[PATCH v4 1/6] iommu/ipmmu-vmsa: Call arm_iommu_release_mapping() in release path

[Lu Baolu]

In the iommu driver's release_device operation, the driver should detach
the device from any attached domain and release the resources allocated
in the probe_device and probe_finalize paths.

Replace arm_iommu_detach_device() with arm_iommu_release_mapping() in the
release path of the ipmmu-vmsa driver. The device_release callback is
called in device_del(), this device is not coming back. Zeroing out
pointers and testing for a condition which cannot be true by construction
is simply a waste of time and code.

The bonus is that it also removes a obstacle of arm_iommu_detach_device()
re-entering the iommu core during release_device. With this removed, the
iommu core code could be simplified a lot.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
Link: https://lore.kernel.org/linux-iommu/7b248ba1-3967-5cd8-82e9-0268c706d320@xxxxxxx/
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
 drivers/iommu/ipmmu-vmsa.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index bdf1a4e5eae0..bc135679523a 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -30,7 +30,6 @@
 #define arm_iommu_create_mapping(...)	NULL
 #define arm_iommu_attach_device(...)	-ENODEV
 #define arm_iommu_release_mapping(...)	do {} while (0)
-#define arm_iommu_detach_device(...)	do {} while (0)
 #endif
 
 #define IPMMU_CTX_MAX		16U
@@ -820,7 +819,18 @@ static void ipmmu_probe_finalize(struct device *dev)
 
 static void ipmmu_release_device(struct device *dev)
 {
-	arm_iommu_detach_device(dev);
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct ipmmu_vmsa_device *mmu = to_ipmmu(dev);
+	unsigned int i;
+
+	for (i = 0; i < fwspec->num_ids; ++i) {
+		unsigned int utlb = fwspec->ids[i];
+
+		ipmmu_imuctr_write(mmu, utlb, 0);
+		mmu->utlb_ctx[utlb] = IPMMU_CTX_INVALID;
+	}
+
+	arm_iommu_release_mapping(mmu->mapping);
 }
 
 static struct iommu_group *ipmmu_find_group(struct device *dev)
-- 
2.34.1