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/sched.h>
12 #include <linux/spinlock.h>
13 #include <linux/bootmem.h>
14 #include <linux/init.h>
15 
16 #include <asm/cputable.h>
17 #include <asm/kvm_ppc.h>
18 #include <asm/kvm_book3s.h>
19 
20 /*
21  * This maintains a list of RMAs (real mode areas) for KVM guests to use.
22  * Each RMA has to be physically contiguous and of a size that the
23  * hardware supports.  PPC970 and POWER7 support 64MB, 128MB and 256MB,
24  * and other larger sizes.  Since we are unlikely to be allocate that
25  * much physically contiguous memory after the system is up and running,
26  * we preallocate a set of RMAs in early boot for KVM to use.
27  */
28 static unsigned long kvm_rma_size = 64 << 20;	/* 64MB */
29 static unsigned long kvm_rma_count;
30 
31 static int __init early_parse_rma_size(char *p)
32 {
33 	if (!p)
34 		return 1;
35 
36 	kvm_rma_size = memparse(p, &p);
37 
38 	return 0;
39 }
40 early_param("kvm_rma_size", early_parse_rma_size);
41 
42 static int __init early_parse_rma_count(char *p)
43 {
44 	if (!p)
45 		return 1;
46 
47 	kvm_rma_count = simple_strtoul(p, NULL, 0);
48 
49 	return 0;
50 }
51 early_param("kvm_rma_count", early_parse_rma_count);
52 
53 static struct kvmppc_rma_info *rma_info;
54 static LIST_HEAD(free_rmas);
55 static DEFINE_SPINLOCK(rma_lock);
56 
57 /* Work out RMLS (real mode limit selector) field value for a given RMA size.
58    Assumes POWER7. */
59 static inline int lpcr_rmls(unsigned long rma_size)
60 {
61 	switch (rma_size) {
62 	case 32ul << 20:	/* 32 MB */
63 		return 8;
64 	case 64ul << 20:	/* 64 MB */
65 		return 3;
66 	case 128ul << 20:	/* 128 MB */
67 		return 7;
68 	case 256ul << 20:	/* 256 MB */
69 		return 4;
70 	case 1ul << 30:		/* 1 GB */
71 		return 2;
72 	case 16ul << 30:	/* 16 GB */
73 		return 1;
74 	case 256ul << 30:	/* 256 GB */
75 		return 0;
76 	default:
77 		return -1;
78 	}
79 }
80 
81 /*
82  * Called at boot time while the bootmem allocator is active,
83  * to allocate contiguous physical memory for the real memory
84  * areas for guests.
85  */
86 void kvm_rma_init(void)
87 {
88 	unsigned long i;
89 	unsigned long j, npages;
90 	void *rma;
91 	struct page *pg;
92 
93 	/* Only do this on POWER7 in HV mode */
94 	if (!cpu_has_feature(CPU_FTR_HVMODE_206))
95 		return;
96 
97 	if (!kvm_rma_size || !kvm_rma_count)
98 		return;
99 
100 	/* Check that the requested size is one supported in hardware */
101 	if (lpcr_rmls(kvm_rma_size) < 0) {
102 		pr_err("RMA size of 0x%lx not supported\n", kvm_rma_size);
103 		return;
104 	}
105 
106 	npages = kvm_rma_size >> PAGE_SHIFT;
107 	rma_info = alloc_bootmem(kvm_rma_count * sizeof(struct kvmppc_rma_info));
108 	for (i = 0; i < kvm_rma_count; ++i) {
109 		rma = alloc_bootmem_align(kvm_rma_size, kvm_rma_size);
110 		pr_info("Allocated KVM RMA at %p (%ld MB)\n", rma,
111 			kvm_rma_size >> 20);
112 		rma_info[i].base_virt = rma;
113 		rma_info[i].base_pfn = __pa(rma) >> PAGE_SHIFT;
114 		rma_info[i].npages = npages;
115 		list_add_tail(&rma_info[i].list, &free_rmas);
116 		atomic_set(&rma_info[i].use_count, 0);
117 
118 		pg = pfn_to_page(rma_info[i].base_pfn);
119 		for (j = 0; j < npages; ++j) {
120 			atomic_inc(&pg->_count);
121 			++pg;
122 		}
123 	}
124 }
125 
126 struct kvmppc_rma_info *kvm_alloc_rma(void)
127 {
128 	struct kvmppc_rma_info *ri;
129 
130 	ri = NULL;
131 	spin_lock(&rma_lock);
132 	if (!list_empty(&free_rmas)) {
133 		ri = list_first_entry(&free_rmas, struct kvmppc_rma_info, list);
134 		list_del(&ri->list);
135 		atomic_inc(&ri->use_count);
136 	}
137 	spin_unlock(&rma_lock);
138 	return ri;
139 }
140 EXPORT_SYMBOL_GPL(kvm_alloc_rma);
141 
142 void kvm_release_rma(struct kvmppc_rma_info *ri)
143 {
144 	if (atomic_dec_and_test(&ri->use_count)) {
145 		spin_lock(&rma_lock);
146 		list_add_tail(&ri->list, &free_rmas);
147 		spin_unlock(&rma_lock);
148 
149 	}
150 }
151 EXPORT_SYMBOL_GPL(kvm_release_rma);
152 
153