[PATCH 1/2][SRU][J/U/OEM-5.17/OEM-5.14] PCI: vmd: Assign VMD IRQ domain before enumeration

Koba Ko koba.ko at canonical.com
Thu Jun 2 06:32:58 UTC 2022

From: Nirmal Patel <nirmal.patel at linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/1976587

During the boot process all the PCI devices are assigned default PCI-MSI
IRQ domain including VMD endpoint devices. If interrupt-remapping is
enabled by IOMMU, the PCI devices except VMD get new INTEL-IR-MSI IRQ
domain. And VMD is supposed to create and assign a separate VMD-MSI IRQ
domain for its child devices in order to support MSI-X remapping

Now when MSI-X remapping in VMD is disabled in order to improve
performance, VMD skips VMD-MSI IRQ domain assignment process to its
child devices. Thus the devices behind VMD get default PCI-MSI IRQ
domain instead of INTEL-IR-MSI IRQ domain when VMD creates root bus and
configures child devices.

As a result host OS fails to boot and DMAR errors were observed when
interrupt remapping was enabled on Intel Icelake CPUs. For instance:

  DMAR: DRHD: handling fault status reg 2
  DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00 [fault reason 0x25] Blocked a compatibility format interrupt request

To fix this issue, dev_msi_info struct in dev struct maintains correct
value of IRQ domain. VMD will use this information to assign proper IRQ
domain to its child devices when it doesn't create a separate IRQ domain.

Link: https://lore.kernel.org/r/20220511095707.25403-2-nirmal.patel@linux.intel.com
Signed-off-by: Nirmal Patel <nirmal.patel at linux.intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
(cherry picked from commit 886e67100b904cb1b106ed1dfa8a60696aff519a git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git)
Signed-off-by: Koba Ko <koba.ko at canonical.com>
 drivers/pci/controller/vmd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index eb05cceab964f..5015adc04d191 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -853,6 +853,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	if (vmd->irq_domain)
 		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
+	else
+		dev_set_msi_domain(&vmd->bus->dev,
+				   dev_get_msi_domain(&vmd->dev->dev));

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