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From: Nirmal Patel <>
To: <>, Nirmal Patel <>
Subject: [PATCH v2 1/2] PCI: vmd: Assign VMD IRQ domain before enumeration
Date: Wed, 11 May 2022 02:57:06 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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.

Signed-off-by: Nirmal Patel <>
v1->v2: Adding more information to commit log.
 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 eb05cceab964..5015adc04d19 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));

  reply	other threads:[~2022-05-11 17:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-11  9:57 [PATCH v2 0/2] PCI: vmd: IRQ domain assignment to sub devices Nirmal Patel
2022-05-11  9:57 ` Nirmal Patel [this message]
2022-05-11  9:57 ` [PATCH v2 2/2] PCI: vmd: Revert 2565e5b69c44 ("PCI: vmd: Do not disable MSI-X remapping if interrupt remapping is enabled by IOMMU.") Nirmal Patel
2022-05-12 14:55 ` [PATCH v2 0/2] PCI: vmd: IRQ domain assignment to sub devices Lorenzo Pieralisi
     [not found] <>
2022-03-29 22:47 ` [PATCH v2 1/2] PCI: vmd: Assign VMD IRQ domain before enumeration Patel, Nirmal
2022-03-29 23:27   ` Dan Williams
2022-03-30 15:54     ` Patel, Nirmal
2022-03-30 17:54       ` Bjorn Helgaas
2022-03-30 18:06         ` Patel, Nirmal
2022-03-30 18:20           ` Bjorn Helgaas

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