Commit 32ab31e0 authored Aug 08, 2012 by Seth Forshee Committed by Joerg Roedel Aug 10, 2012

irq_remap: disable IRQ remapping if any IOAPIC lacks an IOMMU



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.

v2: Move check to parse_ioapics_under_ir(), raise log level to KERN_ERR,
    and add FW_BUG to the log message
v3: Skip check if IOMMU doesn't support interrupt remapping and remove
    existing check that the IOMMU count equals the IOAPIC count

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

parent 31fe9435

drivers/iommu/intel_irq_remapping.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -736,6 +736,7 @@ int __init parse_ioapics_under_ir(void)
		{
		struct dmar_drhd_unit *drhd;
		int ir_supported = 0;
		int ioapic_idx;

		for_each_drhd_unit(drhd) {
		struct intel_iommu *iommu = drhd->iommu;
		@@ -748,13 +749,20 @@ int __init parse_ioapics_under_ir(void)
		}
		}

		if (ir_supported && ir_ioapic_num != nr_ioapics) {
		printk(KERN_WARNING
		"Not all IO-APIC's listed under remapping hardware\n");
		if (!ir_supported)
		return 0;

		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_err(FW_BUG "ioapic %d has no mapping iommu, "
		"interrupt remapping will be disabled\n",
		ioapic_id);
		return -1;
		}
		}

		return ir_supported;
		return 1;
		}

		int __init ir_dev_scope_init(void)