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
hyperv_ir_set_affinity(struct irq_data * data,const struct cpumask * mask,bool force)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 struct IO_APIC_route_entry *entry;
44 int ret;
45
46 /* Return error If new irq affinity is out of ioapic_max_cpumask. */
47 if (!cpumask_subset(mask, &ioapic_max_cpumask))
48 return -EINVAL;
49
50 ret = parent->chip->irq_set_affinity(parent, mask, force);
51 if (ret < 0 || ret == IRQ_SET_MASK_OK_DONE)
52 return ret;
53
54 entry = data->chip_data;
55 entry->dest = cfg->dest_apicid;
56 entry->vector = cfg->vector;
57 send_cleanup_vector(cfg);
58
59 return 0;
60 }
61
62 static struct irq_chip hyperv_ir_chip = {
63 .name = "HYPERV-IR",
64 .irq_ack = apic_ack_irq,
65 .irq_set_affinity = hyperv_ir_set_affinity,
66 };
67
hyperv_irq_remapping_alloc(struct irq_domain * domain,unsigned int virq,unsigned int nr_irqs,void * arg)68 static int hyperv_irq_remapping_alloc(struct irq_domain *domain,
69 unsigned int virq, unsigned int nr_irqs,
70 void *arg)
71 {
72 struct irq_alloc_info *info = arg;
73 struct irq_data *irq_data;
74 struct irq_desc *desc;
75 int ret = 0;
76
77 if (!info || info->type != X86_IRQ_ALLOC_TYPE_IOAPIC || nr_irqs > 1)
78 return -EINVAL;
79
80 ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
81 if (ret < 0)
82 return ret;
83
84 irq_data = irq_domain_get_irq_data(domain, virq);
85 if (!irq_data) {
86 irq_domain_free_irqs_common(domain, virq, nr_irqs);
87 return -EINVAL;
88 }
89
90 irq_data->chip = &hyperv_ir_chip;
91
92 /*
93 * If there is interrupt remapping function of IOMMU, setting irq
94 * affinity only needs to change IRTE of IOMMU. But Hyper-V doesn't
95 * support interrupt remapping function, setting irq affinity of IO-APIC
96 * interrupts still needs to change IO-APIC registers. But ioapic_
97 * configure_entry() will ignore value of cfg->vector and cfg->
98 * dest_apicid when IO-APIC's parent irq domain is not the vector
99 * domain.(See ioapic_configure_entry()) In order to setting vector
100 * and dest_apicid to IO-APIC register, IO-APIC entry pointer is saved
101 * in the chip_data and hyperv_irq_remapping_activate()/hyperv_ir_set_
102 * affinity() set vector and dest_apicid directly into IO-APIC entry.
103 */
104 irq_data->chip_data = info->ioapic_entry;
105
106 /*
107 * Hypver-V IO APIC irq affinity should be in the scope of
108 * ioapic_max_cpumask because no irq remapping support.
109 */
110 desc = irq_data_to_desc(irq_data);
111 cpumask_copy(desc->irq_common_data.affinity, &ioapic_max_cpumask);
112
113 return 0;
114 }
115
hyperv_irq_remapping_free(struct irq_domain * domain,unsigned int virq,unsigned int nr_irqs)116 static void hyperv_irq_remapping_free(struct irq_domain *domain,
117 unsigned int virq, unsigned int nr_irqs)
118 {
119 irq_domain_free_irqs_common(domain, virq, nr_irqs);
120 }
121
hyperv_irq_remapping_activate(struct irq_domain * domain,struct irq_data * irq_data,bool reserve)122 static int hyperv_irq_remapping_activate(struct irq_domain *domain,
123 struct irq_data *irq_data, bool reserve)
124 {
125 struct irq_cfg *cfg = irqd_cfg(irq_data);
126 struct IO_APIC_route_entry *entry = irq_data->chip_data;
127
128 entry->dest = cfg->dest_apicid;
129 entry->vector = cfg->vector;
130
131 return 0;
132 }
133
134 static struct irq_domain_ops hyperv_ir_domain_ops = {
135 .alloc = hyperv_irq_remapping_alloc,
136 .free = hyperv_irq_remapping_free,
137 .activate = hyperv_irq_remapping_activate,
138 };
139
hyperv_prepare_irq_remapping(void)140 static int __init hyperv_prepare_irq_remapping(void)
141 {
142 struct fwnode_handle *fn;
143 int i;
144
145 if (!hypervisor_is_type(X86_HYPER_MS_HYPERV) ||
146 !x2apic_supported())
147 return -ENODEV;
148
149 fn = irq_domain_alloc_named_id_fwnode("HYPERV-IR", 0);
150 if (!fn)
151 return -ENOMEM;
152
153 ioapic_ir_domain =
154 irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
155 0, IOAPIC_REMAPPING_ENTRY, fn,
156 &hyperv_ir_domain_ops, NULL);
157
158 irq_domain_free_fwnode(fn);
159
160 /*
161 * Hyper-V doesn't provide irq remapping function for
162 * IO-APIC and so IO-APIC only accepts 8-bit APIC ID.
163 * Cpu's APIC ID is read from ACPI MADT table and APIC IDs
164 * in the MADT table on Hyper-v are sorted monotonic increasingly.
165 * APIC ID reflects cpu topology. There maybe some APIC ID
166 * gaps when cpu number in a socket is not power of two. Prepare
167 * max cpu affinity for IOAPIC irqs. Scan cpu 0-255 and set cpu
168 * into ioapic_max_cpumask if its APIC ID is less than 256.
169 */
170 for (i = min_t(unsigned int, num_possible_cpus() - 1, 255); i >= 0; i--)
171 if (cpu_physical_id(i) < 256)
172 cpumask_set_cpu(i, &ioapic_max_cpumask);
173
174 return 0;
175 }
176
hyperv_enable_irq_remapping(void)177 static int __init hyperv_enable_irq_remapping(void)
178 {
179 return IRQ_REMAP_X2APIC_MODE;
180 }
181
hyperv_get_ir_irq_domain(struct irq_alloc_info * info)182 static struct irq_domain *hyperv_get_ir_irq_domain(struct irq_alloc_info *info)
183 {
184 if (info->type == X86_IRQ_ALLOC_TYPE_IOAPIC)
185 return ioapic_ir_domain;
186 else
187 return NULL;
188 }
189
190 struct irq_remap_ops hyperv_irq_remap_ops = {
191 .prepare = hyperv_prepare_irq_remapping,
192 .enable = hyperv_enable_irq_remapping,
193 .get_ir_irq_domain = hyperv_get_ir_irq_domain,
194 };
195
196 #endif
197