[RFC PATCH v5 6/7] iommu/amd: Fixup delivery mode of the HPET hardlockup interrupt

[Ricardo Neri]

The HPET hardlockup detector requires that the HPET timer delivers the
interrupt as NMI. When interrupt remapping is disabled, this can be
done by programming the HPET MSI registers directly. With interrupt
remapping, it is necessary to populate an entry in the interrupt
remapping table.

In x86 there is not an IRQF_NMI flag that can be used to indicate the
delivery mode when requesting an interrupt (via request_irq()). Thus,
there is no way for the interrupt remapping driver to know and set
the delivery mode.

Hence, when allocating an interrupt, check if such interrupt belongs to
the HPET hardlockup detector and fixup the delivery mode accordingly.

Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Cc: Andi Kleen <andi.kleen@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> (supporter:INTEL IOMMU (VT-d))
Cc: "Ravi V. Shankar" <ravi.v.shankar@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxx>
Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> (supporter:INTEL IOMMU (VT-d))
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx (open list:INTEL IOMMU (VT-d))
Cc: x86@xxxxxxxxxx
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
---
Changes since v4:
 * Introduced this patch.

Changes since v3:
 * N/A

Changes since v2:
 * N/A

Changes since v1:
 * N/A
---
 drivers/iommu/amd/iommu.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index e8d9fae0c766..758e08ba42e6 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -35,6 +35,7 @@
 #include <asm/irq_remapping.h>
 #include <asm/io_apic.h>
 #include <asm/apic.h>
+#include <asm/hpet.h>
 #include <asm/hw_irq.h>
 #include <asm/proto.h>
 #include <asm/iommu.h>
@@ -3254,6 +3255,14 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 		irq_data->hwirq = (devid << 16) + i;
 		irq_data->chip_data = data;
 		irq_data->chip = &amd_ir_chip;
+
+		/*
+		 * If we find the HPET hardlockup detector irq, fixup the
+		 * delivery mode.
+		 */
+		if (is_hpet_irq_hardlockup_detector(info))
+			cfg->delivery_mode = APIC_DELIVERY_MODE_NMI;
+
 		irq_remapping_prepare_irte(data, cfg, info, devid, index, i);
 		irq_set_status_flags(virq + i, IRQ_MOVE_PCNTXT);
 	}
-- 
2.17.1