[PATCH v7 10/24] iommu/amd: Enable NMIPass when allocating an NMI

[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.

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

Update the NMIPass setting of a device's DTE when an NMI 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
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
---
Changes since v6:
 * Removed check for nr_irqs in irq_remapping_alloc(). Allocation had
   been rejected already in the root domain. (Thomas)

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 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 5a505ba5467e..9bf71e7335f5 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3299,6 +3299,10 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 	if (nr_irqs > 1 && info->type != X86_IRQ_ALLOC_TYPE_PCI_MSI)
 		return -EINVAL;
 
+	/* NMIs are aborted when the destination mode is logical. */
+	if (info->flags & X86_IRQ_ALLOC_AS_NMI && apic->dest_mode_logical)
+		return -EPERM;
+
 	sbdf = get_devid(info);
 	if (sbdf < 0)
 		return -EINVAL;
@@ -3348,6 +3352,13 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 		goto out_free_parent;
 	}
 
+	if (info->flags & X86_IRQ_ALLOC_AS_NMI) {
+		if (!get_dev_entry_bit(iommu, devid, DEV_ENTRY_NMI_PASS)) {
+			set_dev_entry_bit(iommu, 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;
-- 
2.25.1