iommu/vt-d: Allocate DMAR fault interrupts locally

The Intel IOMMU code currently tries to allocate all DMAR fault interrupt
vectors on the boot cpu.  On large systems with high DMAR counts this
results in vector exhaustion, and most of the vectors are not initially
allocated socket local.

Instead, have a cpu on each node do the vector allocation for the DMARs on
that node.  The boot cpu still does the allocation for its node during its
boot sequence.

Signed-off-by: Dimitri Sivanich <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lu Baolu <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>

Author: Dimitri Sivanich

drivers/iommu/amd/amd_iommu.h

@@ -33,7 +33,7 @@ int amd_iommu_prepare(void);
 int amd_iommu_enable(void);
 void amd_iommu_disable(void);
 int amd_iommu_reenable(int mode);
-int amd_iommu_enable_faulting(void);
+int amd_iommu_enable_faulting(unsigned int cpu);
 extern int amd_iommu_guest_ir;
 extern enum io_pgtable_fmt amd_iommu_pgtable;
 extern int amd_iommu_gpt_level;

drivers/iommu/amd/init.c

@@ -3392,7 +3392,7 @@ int amd_iommu_reenable(int mode)
 	return 0;
 }
 
-int __init amd_iommu_enable_faulting(void)
+int __init amd_iommu_enable_faulting(unsigned int cpu)
 {
 	/* We enable MSI later when PCI is initialized */
 	return 0;

drivers/iommu/intel/dmar.c

@@ -2121,7 +2121,7 @@ int dmar_set_interrupt(struct intel_iommu *iommu)
 	return ret;
 }
 
-int __init enable_drhd_fault_handling(void)
+int enable_drhd_fault_handling(unsigned int cpu)
 {
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
@@ -2131,7 +2131,12 @@ int __init enable_drhd_fault_handling(void)
 	 */
 	for_each_iommu(iommu, drhd) {
 		u32 fault_status;
-		int ret = dmar_set_interrupt(iommu);
+		int ret;
+
+		if (iommu->irq || iommu->node != cpu_to_node(cpu))
+			continue;
+
+		ret = dmar_set_interrupt(iommu);
 
 		if (ret) {
 			pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",

drivers/iommu/irq_remapping.c

@@ -151,7 +151,10 @@ int __init irq_remap_enable_fault_handling(void)
 	if (!remap_ops->enable_faulting)
 		return -ENODEV;
 
-	return remap_ops->enable_faulting();
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dmar:enable_fault_handling",
+			  remap_ops->enable_faulting, NULL);
+
+	return remap_ops->enable_faulting(smp_processor_id());
 }
 
 void panic_if_irq_remap(const char *msg)

drivers/iommu/irq_remapping.h

@@ -41,7 +41,7 @@ struct irq_remap_ops {
 	int  (*reenable)(int);
 
 	/* Enable fault handling */
-	int  (*enable_faulting)(void);
+	int  (*enable_faulting)(unsigned int);
 };
 
 extern struct irq_remap_ops intel_irq_remap_ops;

include/linux/dmar.h

@@ -117,7 +117,7 @@ extern int dmar_remove_dev_scope(struct dmar_pci_notify_info *info,
 				 int count);
 /* Intel IOMMU detection */
 void detect_intel_iommu(void);
-extern int enable_drhd_fault_handling(void);
+extern int enable_drhd_fault_handling(unsigned int cpu);
 extern int dmar_device_add(acpi_handle handle);
 extern int dmar_device_remove(acpi_handle handle);