Currently, because domain attach allows to be deferred from iommu driver to device driver, and when iommu initializes, the devices on the bus will be scanned and the default groups will be allocated.
Due to the above changes, some devices could be added to the same group as below: [ 3.859417] pci 0000:01:00.0: Adding to iommu group 16 [ 3.864572] pci 0000:01:00.1: Adding to iommu group 16 [ 3.869738] pci 0000:02:00.0: Adding to iommu group 17 [ 3.874892] pci 0000:02:00.1: Adding to iommu group 17 But when attaching these devices, it doesn't allow that a group has more than one device, otherwise it will return an error. This conflicts with the deferred attaching. Unfortunately, it has two devices in the same group for my side, for example: [ 9.627014] iommu_group_device_count(): device name[0]:0000:01:00.0 [ 9.633545] iommu_group_device_count(): device name[1]:0000:01:00.1 ... [ 10.255609] iommu_group_device_count(): device name[0]:0000:02:00.0 [ 10.262144] iommu_group_device_count(): device name[1]:0000:02:00.1 Finally, which caused the failure of tg3 driver when tg3 driver calls the dma_alloc_coherent() to allocate coherent memory in the tg3_test_dma(). [ 9.660310] tg3 0000:01:00.0: DMA engine test failed, aborting [ 9.754085] tg3: probe of 0000:01:00.0 failed with error -12 [ 9.997512] tg3 0000:01:00.1: DMA engine test failed, aborting [ 10.043053] tg3: probe of 0000:01:00.1 failed with error -12 [ 10.288905] tg3 0000:02:00.0: DMA engine test failed, aborting [ 10.334070] tg3: probe of 0000:02:00.0 failed with error -12 [ 10.578303] tg3 0000:02:00.1: DMA engine test failed, aborting [ 10.622629] tg3: probe of 0000:02:00.1 failed with error -12 In addition, the similar situations also occur in other drivers such as the bnxt_en driver. That can be reproduced easily in kdump kernel when SME is active. Add a check for the deferred attach in the iommu_attach_device() and allow to attach the deferred device regardless of how many devices are in a group. Signed-off-by: Lianbo Jiang <liji...@redhat.com> --- drivers/iommu/iommu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index ffeebda8d6de..dccab7b133fb 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1967,8 +1967,11 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev) */ mutex_lock(&group->mutex); ret = -EINVAL; - if (iommu_group_device_count(group) != 1) + if (!iommu_is_attach_deferred(domain, dev) && + iommu_group_device_count(group) != 1) { + dev_err_ratelimited(dev, "Group has more than one device\n"); goto out_unlock; + } ret = __iommu_attach_group(domain, group); -- 2.17.1