arch/powerpc/kvm/book3s_hv_builtin.c

   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