iommu/amd: Improve page fault error reporting

commit 996d120 upstream.

If IOMMU domain for device group is not setup properly then we may hit
IOMMU page fault. Current page fault handler assumes that domain is
always setup and it will hit NULL pointer derefence (see below sample log).

Lets check whether domain is setup or not and log appropriate message.

Sample log:
----------
 amdgpu 0000:00:01.0: amdgpu: SE 1, SH per SE 1, CU per SH 8, active_cu_number 6
 BUG: kernel NULL pointer dereference, address: 0000000000000058
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 2 PID: 56 Comm: irq/24-AMD-Vi Not tainted 6.2.0-rc2+ #89
 Hardware name: xxx
 RIP: 0010:report_iommu_fault+0x11/0x90
 [...]
 Call Trace:
  <TASK>
  amd_iommu_int_thread+0x60c/0x760
  ? __pfx_irq_thread_fn+0x10/0x10
  irq_thread_fn+0x1f/0x60
  irq_thread+0xea/0x1a0
  ? preempt_count_add+0x6a/0xa0
  ? __pfx_irq_thread_dtor+0x10/0x10
  ? __pfx_irq_thread+0x10/0x10
  kthread+0xe9/0x110
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x2c/0x50
  </TASK>

Reported-by: Matt Fagnani <[email protected]>
Suggested-by: Joerg Roedel <[email protected]>
Signed-off-by: Vasant Hegde <[email protected]>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216865
Link: https://lore.kernel.org/lkml/[email protected]/
Link: https://lore.kernel.org/r/[email protected]
Cc: [email protected]
[joro: Edit commit message]
Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: hegdevasant

drivers/iommu/amd/iommu.c

@@ -558,6 +558,15 @@ static void amd_iommu_report_page_fault(struct amd_iommu *iommu,
 		 * prevent logging it.
 		 */
 		if (IS_IOMMU_MEM_TRANSACTION(flags)) {
+			/* Device not attached to domain properly */
+			if (dev_data->domain == NULL) {
+				pr_err_ratelimited("Event logged [Device not attached to domain properly]\n");
+				pr_err_ratelimited("  device=%04x:%02x:%02x.%x domain=0x%04x\n",
+						   iommu->pci_seg->id, PCI_BUS_NUM(devid), PCI_SLOT(devid),
+						   PCI_FUNC(devid), domain_id);
+				goto out;
+			}
+
 			if (!report_iommu_fault(&dev_data->domain->domain,
 						&pdev->dev, address,
 						IS_WRITE_REQUEST(flags) ?