iommu: Fix false ownership failure on AMD systems with PASID activated

commit 2380f1e8195ef612deea1dc7a3d611c5d2b9b56a upstream.

The AMD IOMMU driver cannot activate PASID mode on a RID without the RID's
translation being set to IDENTITY. Further it requires changing the RID's
page table layout from the normal v1 IOMMU_DOMAIN_IDENTITY layout to a
different v2 layout.

It does this by creating a new iommu_domain, configuring that domain for
v2 identity operation and then attaching it to the group, from within the
driver. This logic assumes the group is already set to the IDENTITY domain
and is being used by the DMA API.

However, since the ownership logic is based on the group's domain pointer
equaling the default domain to detect DMA API ownership, this causes it to
look like the group is not attached to the DMA API any more. This blocks
attaching drivers to any other devices in the group.

In a real system this manifests itself as the HD-audio devices on some AMD
platforms losing their device drivers.

Work around this unique behavior of the AMD driver by checking for
equality of IDENTITY domains based on their type, not their pointer
value. This allows the AMD driver to have two IDENTITY domains for
internal purposes without breaking the check.

Have the AMD driver properly declare that the special domain it created is
actually an IDENTITY domain.

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: stable@vger.kernel.org
Fixes: 512881eacfa7 ("bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management")
Reported-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/0-v1-ea566e16b06b+811-amd_owner_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
index afb3efd565b78ed9f84ff5a5b1ffc9904b5c2f48..f3e2689787ae54c7a1b07ea626af18038d36dacd 100644 (file)
--- a/drivers/iommu/amd/iommu_v2.c
+++ b/drivers/iommu/amd/iommu_v2.c
@@ -786,6 +786,8 @@ int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
        if (dev_state->domain == NULL)
                goto out_free_states;
 
+       /* See iommu_is_default_domain() */
+       dev_state->domain->type = IOMMU_DOMAIN_IDENTITY;
        amd_iommu_domain_direct_map(dev_state->domain);
 
        ret = amd_iommu_domain_enable_v2(dev_state->domain, pasids);

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd38f49085c07b9113130db30733b4..f113833c3075ce3f1a18b5726ce08b1e65cc4549 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3089,6 +3089,24 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
        return ret;
 }
 
+static bool iommu_is_default_domain(struct iommu_group *group)
+{
+       if (group->domain == group->default_domain)
+               return true;
+
+       /*
+        * If the default domain was set to identity and it is still an identity
+        * domain then we consider this a pass. This happens because of
+        * amd_iommu_init_device() replacing the default idenytity domain with an
+        * identity domain that has a different configuration for AMDGPU.
+        */
+       if (group->default_domain &&
+           group->default_domain->type == IOMMU_DOMAIN_IDENTITY &&
+           group->domain && group->domain->type == IOMMU_DOMAIN_IDENTITY)
+               return true;
+       return false;
+}
+
 /**
  * iommu_device_use_default_domain() - Device driver wants to handle device
  *                                     DMA through the kernel DMA API.
@@ -3107,8 +3125,7 @@ int iommu_device_use_default_domain(struct device *dev)
 
        mutex_lock(&group->mutex);
        if (group->owner_cnt) {
-               if (group->domain != group->default_domain ||
-                   group->owner) {
+               if (group->owner || !iommu_is_default_domain(group)) {
                        ret = -EBUSY;
                        goto unlock_out;
                }