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 /*
22  * This maintains a list of RMAs (real mode areas) for KVM guests to use.
23  * Each RMA has to be physically contiguous and of a size that the
24  * hardware supports.  PPC970 and POWER7 support 64MB, 128MB and 256MB,
25  * and other larger sizes.  Since we are unlikely to be allocate that
26  * much physically contiguous memory after the system is up and running,
27  * we preallocate a set of RMAs in early boot for KVM to use.
28  */
29 static unsigned long kvm_rma_size = 64 << 20;	/* 64MB */
30 static unsigned long kvm_rma_count;
31 
32 static int __init early_parse_rma_size(char *p)
33 {
34 	if (!p)
35 		return 1;
36 
37 	kvm_rma_size = memparse(p, &p);
38 
39 	return 0;
40 }
41 early_param("kvm_rma_size", early_parse_rma_size);
42 
43 static int __init early_parse_rma_count(char *p)
44 {
45 	if (!p)
46 		return 1;
47 
48 	kvm_rma_count = simple_strtoul(p, NULL, 0);
49 
50 	return 0;
51 }
52 early_param("kvm_rma_count", early_parse_rma_count);
53 
54 static struct kvmppc_rma_info *rma_info;
55 static LIST_HEAD(free_rmas);
56 static DEFINE_SPINLOCK(rma_lock);
57 
58 /* Work out RMLS (real mode limit selector) field value for a given RMA size.
59    Assumes POWER7 or PPC970. */
60 static inline int lpcr_rmls(unsigned long rma_size)
61 {
62 	switch (rma_size) {
63 	case 32ul << 20:	/* 32 MB */
64 		if (cpu_has_feature(CPU_FTR_ARCH_206))
65 			return 8;	/* only supported on POWER7 */
66 		return -1;
67 	case 64ul << 20:	/* 64 MB */
68 		return 3;
69 	case 128ul << 20:	/* 128 MB */
70 		return 7;
71 	case 256ul << 20:	/* 256 MB */
72 		return 4;
73 	case 1ul << 30:		/* 1 GB */
74 		return 2;
75 	case 16ul << 30:	/* 16 GB */
76 		return 1;
77 	case 256ul << 30:	/* 256 GB */
78 		return 0;
79 	default:
80 		return -1;
81 	}
82 }
83 
84 /*
85  * Called at boot time while the bootmem allocator is active,
86  * to allocate contiguous physical memory for the real memory
87  * areas for guests.
88  */
89 void __init kvm_rma_init(void)
90 {
91 	unsigned long i;
92 	unsigned long j, npages;
93 	void *rma;
94 	struct page *pg;
95 
96 	/* Only do this on PPC970 in HV mode */
97 	if (!cpu_has_feature(CPU_FTR_HVMODE) ||
98 	    !cpu_has_feature(CPU_FTR_ARCH_201))
99 		return;
100 
101 	if (!kvm_rma_size || !kvm_rma_count)
102 		return;
103 
104 	/* Check that the requested size is one supported in hardware */
105 	if (lpcr_rmls(kvm_rma_size) < 0) {
106 		pr_err("RMA size of 0x%lx not supported\n", kvm_rma_size);
107 		return;
108 	}
109 
110 	npages = kvm_rma_size >> PAGE_SHIFT;
111 	rma_info = alloc_bootmem(kvm_rma_count * sizeof(struct kvmppc_rma_info));
112 	for (i = 0; i < kvm_rma_count; ++i) {
113 		rma = alloc_bootmem_align(kvm_rma_size, kvm_rma_size);
114 		pr_info("Allocated KVM RMA at %p (%ld MB)\n", rma,
115 			kvm_rma_size >> 20);
116 		rma_info[i].base_virt = rma;
117 		rma_info[i].base_pfn = __pa(rma) >> PAGE_SHIFT;
118 		rma_info[i].npages = npages;
119 		list_add_tail(&rma_info[i].list, &free_rmas);
120 		atomic_set(&rma_info[i].use_count, 0);
121 
122 		pg = pfn_to_page(rma_info[i].base_pfn);
123 		for (j = 0; j < npages; ++j) {
124 			atomic_inc(&pg->_count);
125 			++pg;
126 		}
127 	}
128 }
129 
130 struct kvmppc_rma_info *kvm_alloc_rma(void)
131 {
132 	struct kvmppc_rma_info *ri;
133 
134 	ri = NULL;
135 	spin_lock(&rma_lock);
136 	if (!list_empty(&free_rmas)) {
137 		ri = list_first_entry(&free_rmas, struct kvmppc_rma_info, list);
138 		list_del(&ri->list);
139 		atomic_inc(&ri->use_count);
140 	}
141 	spin_unlock(&rma_lock);
142 	return ri;
143 }
144 EXPORT_SYMBOL_GPL(kvm_alloc_rma);
145 
146 void kvm_release_rma(struct kvmppc_rma_info *ri)
147 {
148 	if (atomic_dec_and_test(&ri->use_count)) {
149 		spin_lock(&rma_lock);
150 		list_add_tail(&ri->list, &free_rmas);
151 		spin_unlock(&rma_lock);
152 
153 	}
154 }
155 EXPORT_SYMBOL_GPL(kvm_release_rma);
156 
157