1 /*
2  * Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License, version 2, as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/kvm_host.h>
10 #include <linux/preempt.h>
11 #include <linux/export.h>
12 #include <linux/sched.h>
13 #include <linux/spinlock.h>
14 #include <linux/bootmem.h>
15 #include <linux/init.h>
16 
17 #include <asm/cputable.h>
18 #include <asm/kvm_ppc.h>
19 #include <asm/kvm_book3s.h>
20 
21 #define KVM_LINEAR_RMA		0
22 
23 static void __init kvm_linear_init_one(ulong size, int count, int type);
24 static struct kvmppc_linear_info *kvm_alloc_linear(int type);
25 static void kvm_release_linear(struct kvmppc_linear_info *ri);
26 
27 /*************** RMA *************/
28 
29 /*
30  * This maintains a list of RMAs (real mode areas) for KVM guests to use.
31  * Each RMA has to be physically contiguous and of a size that the
32  * hardware supports.  PPC970 and POWER7 support 64MB, 128MB and 256MB,
33  * and other larger sizes.  Since we are unlikely to be allocate that
34  * much physically contiguous memory after the system is up and running,
35  * we preallocate a set of RMAs in early boot for KVM to use.
36  */
37 static unsigned long kvm_rma_size = 64 << 20;	/* 64MB */
38 static unsigned long kvm_rma_count;
39 
40 /* Work out RMLS (real mode limit selector) field value for a given RMA size.
41    Assumes POWER7 or PPC970. */
42 static inline int lpcr_rmls(unsigned long rma_size)
43 {
44 	switch (rma_size) {
45 	case 32ul << 20:	/* 32 MB */
46 		if (cpu_has_feature(CPU_FTR_ARCH_206))
47 			return 8;	/* only supported on POWER7 */
48 		return -1;
49 	case 64ul << 20:	/* 64 MB */
50 		return 3;
51 	case 128ul << 20:	/* 128 MB */
52 		return 7;
53 	case 256ul << 20:	/* 256 MB */
54 		return 4;
55 	case 1ul << 30:		/* 1 GB */
56 		return 2;
57 	case 16ul << 30:	/* 16 GB */
58 		return 1;
59 	case 256ul << 30:	/* 256 GB */
60 		return 0;
61 	default:
62 		return -1;
63 	}
64 }
65 
66 static int __init early_parse_rma_size(char *p)
67 {
68 	if (!p)
69 		return 1;
70 
71 	kvm_rma_size = memparse(p, &p);
72 
73 	return 0;
74 }
75 early_param("kvm_rma_size", early_parse_rma_size);
76 
77 static int __init early_parse_rma_count(char *p)
78 {
79 	if (!p)
80 		return 1;
81 
82 	kvm_rma_count = simple_strtoul(p, NULL, 0);
83 
84 	return 0;
85 }
86 early_param("kvm_rma_count", early_parse_rma_count);
87 
88 struct kvmppc_linear_info *kvm_alloc_rma(void)
89 {
90 	return kvm_alloc_linear(KVM_LINEAR_RMA);
91 }
92 EXPORT_SYMBOL_GPL(kvm_alloc_rma);
93 
94 void kvm_release_rma(struct kvmppc_linear_info *ri)
95 {
96 	kvm_release_linear(ri);
97 }
98 EXPORT_SYMBOL_GPL(kvm_release_rma);
99 
100 /*************** generic *************/
101 
102 static LIST_HEAD(free_linears);
103 static DEFINE_SPINLOCK(linear_lock);
104 
105 static void __init kvm_linear_init_one(ulong size, int count, int type)
106 {
107 	unsigned long i;
108 	unsigned long j, npages;
109 	void *linear;
110 	struct page *pg;
111 	const char *typestr;
112 	struct kvmppc_linear_info *linear_info;
113 
114 	if (!count)
115 		return;
116 
117 	typestr = (type == KVM_LINEAR_RMA) ? "RMA" : "";
118 
119 	npages = size >> PAGE_SHIFT;
120 	linear_info = alloc_bootmem(count * sizeof(struct kvmppc_linear_info));
121 	for (i = 0; i < count; ++i) {
122 		linear = alloc_bootmem_align(size, size);
123 		pr_info("Allocated KVM %s at %p (%ld MB)\n", typestr, linear,
124 			size >> 20);
125 		linear_info[i].base_virt = linear;
126 		linear_info[i].base_pfn = __pa(linear) >> PAGE_SHIFT;
127 		linear_info[i].npages = npages;
128 		linear_info[i].type = type;
129 		list_add_tail(&linear_info[i].list, &free_linears);
130 		atomic_set(&linear_info[i].use_count, 0);
131 
132 		pg = pfn_to_page(linear_info[i].base_pfn);
133 		for (j = 0; j < npages; ++j) {
134 			atomic_inc(&pg->_count);
135 			++pg;
136 		}
137 	}
138 }
139 
140 static struct kvmppc_linear_info *kvm_alloc_linear(int type)
141 {
142 	struct kvmppc_linear_info *ri;
143 
144 	ri = NULL;
145 	spin_lock(&linear_lock);
146 	list_for_each_entry(ri, &free_linears, list) {
147 		if (ri->type != type)
148 			continue;
149 
150 		list_del(&ri->list);
151 		atomic_inc(&ri->use_count);
152 		break;
153 	}
154 	spin_unlock(&linear_lock);
155 	memset(ri->base_virt, 0, ri->npages << PAGE_SHIFT);
156 	return ri;
157 }
158 
159 static void kvm_release_linear(struct kvmppc_linear_info *ri)
160 {
161 	if (atomic_dec_and_test(&ri->use_count)) {
162 		spin_lock(&linear_lock);
163 		list_add_tail(&ri->list, &free_linears);
164 		spin_unlock(&linear_lock);
165 
166 	}
167 }
168 
169 /*
170  * Called at boot time while the bootmem allocator is active,
171  * to allocate contiguous physical memory for the hash page
172  * tables for guests.
173  */
174 void __init kvm_linear_init(void)
175 {
176 	/* RMA */
177 	/* Only do this on PPC970 in HV mode */
178 	if (!cpu_has_feature(CPU_FTR_HVMODE) ||
179 	    !cpu_has_feature(CPU_FTR_ARCH_201))
180 		return;
181 
182 	if (!kvm_rma_size || !kvm_rma_count)
183 		return;
184 
185 	/* Check that the requested size is one supported in hardware */
186 	if (lpcr_rmls(kvm_rma_size) < 0) {
187 		pr_err("RMA size of 0x%lx not supported\n", kvm_rma_size);
188 		return;
189 	}
190 
191 	kvm_linear_init_one(kvm_rma_size, kvm_rma_count, KVM_LINEAR_RMA);
192 }
193