Re: [regression, bisected, pci/iommu] Bug 216865 - Black screen when amdgpu started during 6.2-rc1 boot with AMD IOMMU enabled

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Feb 15, 2023 at 07:35:45PM -0500, Felix Kuehling wrote:
> 
> If I understand this correctly, the HW or the BIOS is doing something wrong
> about reporting ACS. I don't know what the GPU driver can do other than add
> some quirk to stop using AMD IOMMUv2 on this HW/BIOS.

How about this:

diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
index 864e4ffb6aa94e..cc027ce9a6e86f 100644
--- a/drivers/iommu/amd/iommu_v2.c
+++ b/drivers/iommu/amd/iommu_v2.c
@@ -732,6 +732,7 @@ EXPORT_SYMBOL(amd_iommu_unbind_pasid);
 
 int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
 {
+	struct iommu_dev_data *dev_data = dev_iommu_priv_get(&pdev->dev);
 	struct device_state *dev_state;
 	struct iommu_group *group;
 	unsigned long flags;
@@ -740,6 +741,9 @@ int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
 
 	might_sleep();
 
+	if (!dev_data->ats.enabled)
+		return -EINVAL;
+
 	/*
 	 * When memory encryption is active the device is likely not in a
 	 * direct-mapped domain. Forbid using IOMMUv2 functionality for now.