iommu/amd: Put list_add/del(dev_data) back under the domain->lock

The list domain->dev_list is protected by the domain->lock spinlock.
Any iteration, addition or removal must be under the lock.

Move the list_del() up into the critical section. pdom_is_sva_capable(),
and destroy_gcr3_table() do not interact with the list element.

Wrap the list_add() in a lock, it would make more sense if this was under
the same critical section as adjusting the refcounts earlier, but that
requires more complications.

Fixes: d6b47dec3684 ("iommu/amd: Reduce domain lock scope in attach device path")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/1-v1-3b9edcf8067d+3975-amd_dev_list_locking_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 3f691e1fd22ce4bb5433d852512c7dbf90233e8e..23a168e229b171b973b1a6836c5f5baa9958dd1c 100644 (file)
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2073,6 +2073,7 @@ static int attach_device(struct device *dev,
        struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
        struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
        struct pci_dev *pdev;
+       unsigned long flags;
        int ret = 0;
 
        mutex_lock(&dev_data->mutex);
@@ -2113,7 +2114,9 @@ static int attach_device(struct device *dev,
 
        /* Update data structures */
        dev_data->domain = domain;
+       spin_lock_irqsave(&domain->lock, flags);
        list_add(&dev_data->list, &domain->dev_list);
+       spin_unlock_irqrestore(&domain->lock, flags);
 
        /* Update device table */
        dev_update_dte(dev_data, true);
@@ -2160,6 +2163,7 @@ static void detach_device(struct device *dev)
        /* Flush IOTLB and wait for the flushes to finish */
        spin_lock_irqsave(&domain->lock, flags);
        amd_iommu_domain_flush_all(domain);
+       list_del(&dev_data->list);
        spin_unlock_irqrestore(&domain->lock, flags);
 
        /* Clear GCR3 table */
@@ -2168,7 +2172,6 @@ static void detach_device(struct device *dev)
 
        /* Update data structures */
        dev_data->domain = NULL;
-       list_del(&dev_data->list);
 
        /* decrease reference counters - needs to happen after the flushes */
        pdom_detach_iommu(iommu, domain);