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    Subject[PATCH v4 1/6] iommu/ipmmu-vmsa: Call arm_iommu_release_mapping() in release path
    Date
    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@nvidia.com>
    Suggested-by: Robin Murphy <robin.murphy@arm.com>
    Link: https://lore.kernel.org/linux-iommu/7b248ba1-3967-5cd8-82e9-0268c706d320@arm.com/
    Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
    ---
    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
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