intel-iommu: Fix kernel hang if interrupt remapping disabled in BIOS

BIOS clear DMAR table INTR_REMAP flag to disable interrupt remapping. Current
kernel only check interrupt remapping(IR) flag in DRHD's extended capability
register to decide interrupt remapping support or not. But IR flag will not
change when BIOS disable/enable interrupt remapping.

When user disable interrupt remapping in BIOS or BIOS often defaultly disable
interrupt remapping feature when BIOS is not mature.Though BIOS disable
interrupt remapping but intr_remapping_supported function will always report
to OS support interrupt remapping if VT-d2 chipset populated. On this
cases, kernel will continue enable interrupt remapping and result kernel panic.
This bug exist on almost all platforms with interrupt remapping support.

This patch add DMAR table INTR_REMAP flag check before enable interrupt
remapping.

Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index fba4f6891680f657ff69a698dd95b5e753408233..270ed222a075912175fe1fe2d26f63a901729f66 100644 (file)
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -1316,3 +1316,13 @@ int dmar_reenable_qi(struct intel_iommu *iommu)
 
        return 0;
 }
+
+/*
+ * Check interrupt remapping support in DMAR table description.
+ */
+int dmar_ir_support(void)
+{
+       struct acpi_table_dmar *dmar;
+       dmar = (struct acpi_table_dmar *)dmar_tbl;
+       return dmar->flags & 0x1;
+}

diff --git a/drivers/pci/intr_remapping.c b/drivers/pci/intr_remapping.c
index ebfa47b79c5b595900cb0c19511d0734e2866ac6..ac065144c01cbff2ca57846b6b3c6a9153935498 100644 (file)
--- a/drivers/pci/intr_remapping.c
+++ b/drivers/pci/intr_remapping.c
@@ -611,6 +611,9 @@ int __init intr_remapping_supported(void)
        if (disable_intremap)
                return 0;
 
+       if (!dmar_ir_support())
+               return 0;
+
        for_each_drhd_unit(drhd) {
                struct intel_iommu *iommu = drhd->iommu;
 

diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 482dc91fd53a3ab0a0a072dd55537ca0012c3c67..4f0a72a9740cfa86220e3a22816445e36a986705 100644 (file)
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -360,4 +360,6 @@ extern void qi_flush_dev_iotlb(struct intel_iommu *iommu, u16 sid, u16 qdep,
 
 extern int qi_submit_sync(struct qi_desc *desc, struct intel_iommu *iommu);
 
+extern int dmar_ir_support(void);
+
 #endif