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Old 08-10-2012, 09:25 PM
Seth Forshee
 
Default UBUNTU: SAUCE: (drop after 3.6) 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>
(cherry picked from commit 32ab31e01e2def6f48294d872d9bb42573aae00f
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git)
BugLink: http://bugs.launchpad.net/bugs/1034459
---
drivers/iommu/intel_irq_remapping.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 6d34706..55fe60d 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -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
");
- return -1;
+ 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
",
+ ioapic_id);
+ return -1;
+ }
}

- return ir_supported;
+ return 1;
}

int __init ir_dev_scope_init(void)
--
1.7.9.5


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