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Subject[34-longterm 181/209] x86, vt-d: Quirk for masking vtd spec errors to platform error handling logic
From: Suresh Siddha <>

| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|

commit 254e42006c893f45bca48f313536fcba12206418 upstream.

On platforms with Intel 7500 chipset, there were some reports of system
hang/NMI's during kexec/kdump in the presence of interrupt-remapping enabled.

During kdump, there is a window where the devices might be still using old
kernel's interrupt information, while the kdump kernel is coming up. This can
cause vt-d faults as the interrupt configuration from the old kernel map to
null IRTE entries in the new kernel etc. (with out interrupt-remapping enabled,
we still have the same issue but in this case we will see benign spurious
interrupt hit the new kernel).

Based on platform config settings, these platforms seem to generate NMI/SMI
when a vt-d fault happens and there were reports that the resulting SMI causes
the system to hang.

Fix it by masking vt-d spec defined errors to platform error reporting logic.
VT-d spec related errors are already handled by the VT-d OS code, so need to
report the same error through other channels.

Signed-off-by: Suresh Siddha <>
LKML-Reference: <>
Reported-by: Max Asbock <>
Reported-and-tested-by: Takao Indoh <>
Acked-by: Chris Wright <>
Acked-by: Kenji Kaneshige <>
Signed-off-by: H. Peter Anvin <>
Signed-off-by: Paul Gortmaker <>
drivers/pci/quirks.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 4a120b7..ccc2683 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c

+#if defined(CONFIG_DMAR) || defined(CONFIG_INTR_REMAP)
+#define VTUNCERRMSK_REG 0x1ac
+#define VTD_MSK_SPEC_ERRORS (1 << 31)
+ * This is a quirk for masking vt-d spec defined errors to platform error
+ * handling logic. With out this, platforms using Intel 7500, 5500 chipsets
+ * (and the derivative chipsets like X58 etc) seem to generate NMI/SMI (based
+ * on the RAS config settings of the platform) when a vt-d fault happens.
+ * The resulting SMI caused the system to hang.
+ *
+ * VT-d spec related errors are already handled by the VT-d OS code, so no
+ * need to report the same error through other channels.
+ */
+static void vtd_mask_spec_errors(struct pci_dev *dev)
+ u32 word;
+ pci_read_config_dword(dev, VTUNCERRMSK_REG, &word);
+ pci_write_config_dword(dev, VTUNCERRMSK_REG, word | VTD_MSK_SPEC_ERRORS);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x342e, vtd_mask_spec_errors);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x3c28, vtd_mask_spec_errors);

static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
struct pci_fixup *end)

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