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/cpu.h>
  10 #include <linux/kvm_host.h>
  11 #include <linux/preempt.h>
  12 #include <linux/export.h>
  13 #include <linux/sched.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/bootmem.h>
  16 #include <linux/init.h>
  17 #include <linux/memblock.h>
  18 #include <linux/sizes.h>
  19 #include <linux/cma.h>
  20
  21 #include <asm/cputable.h>
  22 #include <asm/kvm_ppc.h>
  23 #include <asm/kvm_book3s.h>
  24
  25 #define KVM_CMA_CHUNK_ORDER     18
  26
  27 /*
  28  * Hash page table alignment on newer cpus(CPU_FTR_ARCH_206)
  29  * should be power of 2.
  30  */
  31 #define HPT_ALIGN_PAGES         ((1 << 18) >> PAGE_SHIFT) /* 256k */
  32 /*
  33  * By default we reserve 5% of memory for hash pagetable allocation.
  34  */
  35 static unsigned long kvm_cma_resv_ratio = 5;
  36 /*
  37  * We allocate RMAs (real mode areas) for KVM guests from the KVM CMA area.
  38  * Each RMA has to be physically contiguous and of a size that the
  39  * hardware supports.  PPC970 and POWER7 support 64MB, 128MB and 256MB,
  40  * and other larger sizes.  Since we are unlikely to be allocate that
  41  * much physically contiguous memory after the system is up and running,
  42  * we preallocate a set of RMAs in early boot using CMA.
  43  * should be power of 2.
  44  */
  45 unsigned long kvm_rma_pages = (1 << 27) >> PAGE_SHIFT;  /* 128MB */
  46 EXPORT_SYMBOL_GPL(kvm_rma_pages);
  47
  48 static struct cma *kvm_cma;
  49
  50 /* Work out RMLS (real mode limit selector) field value for a given RMA size.
  51    Assumes POWER7 or PPC970. */
  52 static inline int lpcr_rmls(unsigned long rma_size)
  53 {
  54         switch (rma_size) {
  55         case 32ul << 20:        /* 32 MB */
  56                 if (cpu_has_feature(CPU_FTR_ARCH_206))
  57                         return 8;       /* only supported on POWER7 */
  58                 return -1;
  59         case 64ul << 20:        /* 64 MB */
  60                 return 3;
  61         case 128ul << 20:       /* 128 MB */
  62                 return 7;
  63         case 256ul << 20:       /* 256 MB */
  64                 return 4;
  65         case 1ul << 30:         /* 1 GB */
  66                 return 2;
  67         case 16ul << 30:        /* 16 GB */
  68                 return 1;
  69         case 256ul << 30:       /* 256 GB */
  70                 return 0;
  71         default:
  72                 return -1;
  73         }
  74 }
  75
  76 static int __init early_parse_rma_size(char *p)
  77 {
  78         unsigned long kvm_rma_size;
  79
  80         pr_debug("%s(%s)\n", __func__, p);
  81         if (!p)
  82                 return -EINVAL;
  83         kvm_rma_size = memparse(p, &p);
  84         /*
  85          * Check that the requested size is one supported in hardware
  86          */
  87         if (lpcr_rmls(kvm_rma_size) < 0) {
  88                 pr_err("RMA size of 0x%lx not supported\n", kvm_rma_size);
  89                 return -EINVAL;
  90         }
  91         kvm_rma_pages = kvm_rma_size >> PAGE_SHIFT;
  92         return 0;
  93 }
  94 early_param("kvm_rma_size", early_parse_rma_size);
  95
  96 struct kvm_rma_info *kvm_alloc_rma()
  97 {
  98         struct page *page;
  99         struct kvm_rma_info *ri;
 100
 101         ri = kmalloc(sizeof(struct kvm_rma_info), GFP_KERNEL);
 102         if (!ri)
 103                 return NULL;
 104         page = cma_alloc(kvm_cma, kvm_rma_pages, order_base_2(kvm_rma_pages));
 105         if (!page)
 106                 goto err_out;
 107         atomic_set(&ri->use_count, 1);
 108         ri->base_pfn = page_to_pfn(page);
 109         return ri;
 110 err_out:
 111         kfree(ri);
 112         return NULL;
 113 }
 114 EXPORT_SYMBOL_GPL(kvm_alloc_rma);
 115
 116 void kvm_release_rma(struct kvm_rma_info *ri)
 117 {
 118         if (atomic_dec_and_test(&ri->use_count)) {
 119                 cma_release(kvm_cma, pfn_to_page(ri->base_pfn), kvm_rma_pages);
 120                 kfree(ri);
 121         }
 122 }
 123 EXPORT_SYMBOL_GPL(kvm_release_rma);
 124
 125 static int __init early_parse_kvm_cma_resv(char *p)
 126 {
 127         pr_debug("%s(%s)\n", __func__, p);
 128         if (!p)
 129                 return -EINVAL;
 130         return kstrtoul(p, 0, &kvm_cma_resv_ratio);
 131 }
 132 early_param("kvm_cma_resv_ratio", early_parse_kvm_cma_resv);
 133
 134 struct page *kvm_alloc_hpt(unsigned long nr_pages)
 135 {
 136         unsigned long align_pages = HPT_ALIGN_PAGES;
 137
 138         VM_BUG_ON(order_base_2(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
 139
 140         /* Old CPUs require HPT aligned on a multiple of its size */
 141         if (!cpu_has_feature(CPU_FTR_ARCH_206))
 142                 align_pages = nr_pages;
 143         return cma_alloc(kvm_cma, nr_pages, order_base_2(align_pages));
 144 }
 145 EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
 146
 147 void kvm_release_hpt(struct page *page, unsigned long nr_pages)
 148 {
 149         cma_release(kvm_cma, page, nr_pages);
 150 }
 151 EXPORT_SYMBOL_GPL(kvm_release_hpt);
 152
 153 /**
 154  * kvm_cma_reserve() - reserve area for kvm hash pagetable
 155  *
 156  * This function reserves memory from early allocator. It should be
 157  * called by arch specific code once the early allocator (memblock or bootmem)
 158  * has been activated and all other subsystems have already allocated/reserved
 159  * memory.
 160  */
 161 void __init kvm_cma_reserve(void)
 162 {
 163         unsigned long align_size;
 164         struct memblock_region *reg;
 165         phys_addr_t selected_size = 0;
 166         /*
 167          * We cannot use memblock_phys_mem_size() here, because
 168          * memblock_analyze() has not been called yet.
 169          */
 170         for_each_memblock(memory, reg)
 171                 selected_size += memblock_region_memory_end_pfn(reg) -
 172                                  memblock_region_memory_base_pfn(reg);
 173
 174         selected_size = (selected_size * kvm_cma_resv_ratio / 100) << PAGE_SHIFT;
 175         if (selected_size) {
 176                 pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 177                          (unsigned long)selected_size / SZ_1M);
 178                 /*
 179                  * Old CPUs require HPT aligned on a multiple of its size. So for them
 180                  * make the alignment as max size we could request.
 181                  */
 182                 if (!cpu_has_feature(CPU_FTR_ARCH_206))
 183                         align_size = __rounddown_pow_of_two(selected_size);
 184                 else
 185                         align_size = HPT_ALIGN_PAGES << PAGE_SHIFT;
 186
 187                 align_size = max(kvm_rma_pages << PAGE_SHIFT, align_size);
 188                 cma_declare_contiguous(0, selected_size, 0, align_size,
 189                         KVM_CMA_CHUNK_ORDER - PAGE_SHIFT, false, &kvm_cma);
 190         }
 191 }
 192
 193 /*
 194  * When running HV mode KVM we need to block certain operations while KVM VMs
 195  * exist in the system. We use a counter of VMs to track this.
 196  *
 197  * One of the operations we need to block is onlining of secondaries, so we
 198  * protect hv_vm_count with get/put_online_cpus().
 199  */
 200 static atomic_t hv_vm_count;
 201
 202 void kvm_hv_vm_activated(void)
 203 {
 204         get_online_cpus();
 205         atomic_inc(&hv_vm_count);
 206         put_online_cpus();
 207 }
 208 EXPORT_SYMBOL_GPL(kvm_hv_vm_activated);
 209
 210 void kvm_hv_vm_deactivated(void)
 211 {
 212         get_online_cpus();
 213         atomic_dec(&hv_vm_count);
 214         put_online_cpus();
 215 }
 216 EXPORT_SYMBOL_GPL(kvm_hv_vm_deactivated);
 217
 218 bool kvm_hv_mode_active(void)
 219 {
 220         return atomic_read(&hv_vm_count) != 0;
 221 }
 222
 223 extern int hcall_real_table[], hcall_real_table_end[];
 224
 225 int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
 226 {
 227         cmd /= 4;
 228         if (cmd < hcall_real_table_end - hcall_real_table &&
 229             hcall_real_table[cmd])
 230                 return 1;
 231
 232         return 0;
 233 }
 234 EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);