1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * Hyper-V stub IOMMU driver. 5 * 6 * Copyright (C) 2019, Microsoft, Inc. 7 * 8 * Author : Lan Tianyu <Tianyu.Lan@microsoft.com> 9 */ 10 11 #include <linux/types.h> 12 #include <linux/interrupt.h> 13 #include <linux/irq.h> 14 #include <linux/iommu.h> 15 #include <linux/module.h> 16 17 #include <asm/apic.h> 18 #include <asm/cpu.h> 19 #include <asm/hw_irq.h> 20 #include <asm/io_apic.h> 21 #include <asm/irq_remapping.h> 22 #include <asm/hypervisor.h> 23 24 #include "irq_remapping.h" 25 26 #ifdef CONFIG_IRQ_REMAP 27 28 /* 29 * According 82093AA IO-APIC spec , IO APIC has a 24-entry Interrupt 30 * Redirection Table. Hyper-V exposes one single IO-APIC and so define 31 * 24 IO APIC remmapping entries. 32 */ 33 #define IOAPIC_REMAPPING_ENTRY 24 34 35 static cpumask_t ioapic_max_cpumask = { CPU_BITS_NONE }; 36 static struct irq_domain *ioapic_ir_domain; 37 38 static int hyperv_ir_set_affinity(struct irq_data *data, 39 const struct cpumask *mask, bool force) 40 { 41 struct irq_data *parent = data->parent_data; 42 struct irq_cfg *cfg = irqd_cfg(data); 43 int ret; 44 45 /* Return error If new irq affinity is out of ioapic_max_cpumask. */ 46 if (!cpumask_subset(mask, &ioapic_max_cpumask)) 47 return -EINVAL; 48 49 ret = parent->chip->irq_set_affinity(parent, mask, force); 50 if (ret < 0 || ret == IRQ_SET_MASK_OK_DONE) 51 return ret; 52 53 send_cleanup_vector(cfg); 54 55 return 0; 56 } 57 58 static struct irq_chip hyperv_ir_chip = { 59 .name = "HYPERV-IR", 60 .irq_ack = apic_ack_irq, 61 .irq_set_affinity = hyperv_ir_set_affinity, 62 }; 63 64 static int hyperv_irq_remapping_alloc(struct irq_domain *domain, 65 unsigned int virq, unsigned int nr_irqs, 66 void *arg) 67 { 68 struct irq_alloc_info *info = arg; 69 struct irq_data *irq_data; 70 struct irq_desc *desc; 71 int ret = 0; 72 73 if (!info || info->type != X86_IRQ_ALLOC_TYPE_IOAPIC || nr_irqs > 1) 74 return -EINVAL; 75 76 ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg); 77 if (ret < 0) 78 return ret; 79 80 irq_data = irq_domain_get_irq_data(domain, virq); 81 if (!irq_data) { 82 irq_domain_free_irqs_common(domain, virq, nr_irqs); 83 return -EINVAL; 84 } 85 86 irq_data->chip = &hyperv_ir_chip; 87 88 /* 89 * Hypver-V IO APIC irq affinity should be in the scope of 90 * ioapic_max_cpumask because no irq remapping support. 91 */ 92 desc = irq_data_to_desc(irq_data); 93 cpumask_copy(desc->irq_common_data.affinity, &ioapic_max_cpumask); 94 95 return 0; 96 } 97 98 static void hyperv_irq_remapping_free(struct irq_domain *domain, 99 unsigned int virq, unsigned int nr_irqs) 100 { 101 irq_domain_free_irqs_common(domain, virq, nr_irqs); 102 } 103 104 static int hyperv_irq_remapping_select(struct irq_domain *d, 105 struct irq_fwspec *fwspec, 106 enum irq_domain_bus_token bus_token) 107 { 108 /* Claim the only I/O APIC emulated by Hyper-V */ 109 return x86_fwspec_is_ioapic(fwspec); 110 } 111 112 static const struct irq_domain_ops hyperv_ir_domain_ops = { 113 .select = hyperv_irq_remapping_select, 114 .alloc = hyperv_irq_remapping_alloc, 115 .free = hyperv_irq_remapping_free, 116 }; 117 118 static int __init hyperv_prepare_irq_remapping(void) 119 { 120 struct fwnode_handle *fn; 121 int i; 122 123 if (!hypervisor_is_type(X86_HYPER_MS_HYPERV) || 124 x86_init.hyper.msi_ext_dest_id() || 125 !x2apic_supported()) 126 return -ENODEV; 127 128 fn = irq_domain_alloc_named_id_fwnode("HYPERV-IR", 0); 129 if (!fn) 130 return -ENOMEM; 131 132 ioapic_ir_domain = 133 irq_domain_create_hierarchy(arch_get_ir_parent_domain(), 134 0, IOAPIC_REMAPPING_ENTRY, fn, 135 &hyperv_ir_domain_ops, NULL); 136 137 if (!ioapic_ir_domain) { 138 irq_domain_free_fwnode(fn); 139 return -ENOMEM; 140 } 141 142 /* 143 * Hyper-V doesn't provide irq remapping function for 144 * IO-APIC and so IO-APIC only accepts 8-bit APIC ID. 145 * Cpu's APIC ID is read from ACPI MADT table and APIC IDs 146 * in the MADT table on Hyper-v are sorted monotonic increasingly. 147 * APIC ID reflects cpu topology. There maybe some APIC ID 148 * gaps when cpu number in a socket is not power of two. Prepare 149 * max cpu affinity for IOAPIC irqs. Scan cpu 0-255 and set cpu 150 * into ioapic_max_cpumask if its APIC ID is less than 256. 151 */ 152 for (i = min_t(unsigned int, num_possible_cpus() - 1, 255); i >= 0; i--) 153 if (cpu_physical_id(i) < 256) 154 cpumask_set_cpu(i, &ioapic_max_cpumask); 155 156 return 0; 157 } 158 159 static int __init hyperv_enable_irq_remapping(void) 160 { 161 return IRQ_REMAP_X2APIC_MODE; 162 } 163 164 struct irq_remap_ops hyperv_irq_remap_ops = { 165 .prepare = hyperv_prepare_irq_remapping, 166 .enable = hyperv_enable_irq_remapping, 167 }; 168 169 #endif 170