From: David Woodhouse
The AMD IOMMU initialisation registers the IRQ remapping domain for
each IOMMU before doing the final sanity check that every I/OAPIC is
covered.
This means that the AMD irq_remapping_select() function gets invoked
even when IRQ remapping has been disabled, eventually leading to a NULL
pointer dereference in alloc_irq_table().
Unfortunately, the IVRS isn't fully parsed early enough that the sanity
check can be done in time to registering the IRQ domain altogether.
Doing that would be nice, but is a larger and more error-prone task. The
simple fix is just for irq_remapping_select() to refuse to report a
match when IRQ remapping has disabled.
Link: https://lore.kernel.org/lkml/ed4be9b4-24ac-7128-c522-7ef359e81...@gmx.at
Fixes: a1a785b57242 ("iommu/amd: Implement select() method on remapping
irqdomain")
Reported-by: Johnathan Smithinovic
Signed-off-by: David Woodhouse
---
drivers/iommu/amd/iommu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 7e2c445a1fae..f0adbc48fd17 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3854,6 +3854,9 @@ static int irq_remapping_select(struct irq_domain *d,
struct irq_fwspec *fwspec,
struct amd_iommu *iommu;
int devid = -1;
+ if (!amd_iommu_irq_remap)
+ return 0;
+
if (x86_fwspec_is_ioapic(fwspec))
devid = get_ioapic_devid(fwspec->param[0]);
else if (x86_fwspec_is_hpet(fwspec))
--
2.29.2
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