The ACS requirement has been obscured in the current code and is only known by certain individuals who happen to read the code. Print out a warning with ACS path failure when ACS requirement is not met. Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx> --- drivers/iommu/iommu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index dbe7f65..049ee0a 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -811,6 +811,9 @@ struct iommu_group *pci_device_group(struct device *dev) if (IS_ERR(group)) return NULL; + if (pci_is_root_bus(bus)) + dev_warn_once(&pdev->dev, "using shared group due to ACS path failure\n"); + return group; } -- 1.9.1
