[PATCH v6 12/29] iommu/amd: Enable NMIPass when allocating an NMI irq

[Ricardo Neri]

As per the AMD I/O Virtualization Technology (IOMMU) Specification, the
AMD IOMMU only remaps fixed and arbitrated MSIs. NMIs are controlled
by the NMIPass bit of a Device Table Entry. When set, the IOMMU passes
through NMI interrupt messages unmapped. Otherwise, they are aborted.

Furthermore, Section 2.2.5 Table 19 states that the IOMMU will also
abort NMIs when the destination mode is logical.

Update the NMIPass setting of a device's DTE when an NMI irq is being
allocated. Only do so when the destination mode of the APIC is not
logical.

Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: "Ravi V. Shankar" <ravi.v.shankar@xxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
---
Changes since v5:
 * Introduced this patch

Changes since v4:
 * N/A

Changes since v3:
 * N/A

Changes since v2:
 * N/A

Changes since v1:
 * N/A
---
 drivers/iommu/amd/iommu.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..4d7421b6858d 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3156,6 +3156,15 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 	    info->type != X86_IRQ_ALLOC_TYPE_PCI_MSIX)
 		return -EINVAL;
 
+	if (info->flags & X86_IRQ_ALLOC_AS_NMI) {
+		/* Only one IRQ per NMI */
+		if (nr_irqs != 1)
+			return -EINVAL;
+
+		/* NMIs are aborted when the destination mode is logical. */
+		if (apic->dest_mode_logical)
+			return -EPERM;
+	}
 	/*
 	 * With IRQ remapping enabled, don't need contiguous CPU vectors
 	 * to support multiple MSI interrupts.
@@ -3208,6 +3217,15 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 		goto out_free_parent;
 	}
 
+	if (info->flags & X86_IRQ_ALLOC_AS_NMI) {
+		struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];
+
+		if (!get_dev_entry_bit(devid, DEV_ENTRY_NMI_PASS)) {
+			set_dev_entry_bit(devid, DEV_ENTRY_NMI_PASS);
+			iommu_flush_dte(iommu, devid);
+		}
+	}
+
 	for (i = 0; i < nr_irqs; i++) {
 		irq_data = irq_domain_get_irq_data(domain, virq + i);
 		cfg = irq_data ? irqd_cfg(irq_data) : NULL;
-- 
2.17.1