The ACPI tables in the Macbook Air 5,1 define a single IOAPIC with id 2,
but the only remapping unit described in the DMAR table matches id 0.
Interrupt remapping fails as a result, and the kernel panics with the
message "timer doesn't work through Interrupt-remapped IO-APIC."
To fix this, check each IOAPIC for a corresponding IOMMU. If an IOMMU is
not found, do not allow IRQ remapping to be enabled.
Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
---
drivers/iommu/intel_irq_remapping.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index e0b18f3..ce2c0c6 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -526,6 +526,7 @@ static int __init intel_irq_remapping_supported(void)
static int __init intel_enable_irq_remapping(void)
{
struct dmar_drhd_unit *drhd;
+ int ioapic_idx;
int setup = 0;
int eim = 0;
@@ -534,6 +535,16 @@ static int __init intel_enable_irq_remapping(void)
return -1;
}
+ for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
+ int ioapic_id = mpc_ioapic_id(ioapic_idx);
+ if (!map_ioapic_to_ir(ioapic_id)) {
+ pr_info("ioapic %d has no mapping iommu, "
+ "interrupt remapping will be disabled\n",
+ ioapic_id);
+ return -1;
+ }
+ }
+
if (x2apic_supported()) {
eim = !dmar_x2apic_optout();
WARN(!eim, KERN_WARNING
--
1.7.9.5
--
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