arch/powerpc/kernel/kvm.c

   1 /*
   2  * Copyright (C) 2010 SUSE Linux Products GmbH. All rights reserved.
   3  *
   4  * Authors:
   5  *     Alexander Graf <agraf@suse.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License, version 2, as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  19  */
  20
  21 #include <linux/kvm_host.h>
  22 #include <linux/init.h>
  23 #include <linux/kvm_para.h>
  24 #include <linux/slab.h>
  25 #include <linux/of.h>
  26
  27 #include <asm/reg.h>
  28 #include <asm/kvm_ppc.h>
  29 #include <asm/sections.h>
  30 #include <asm/cacheflush.h>
  31 #include <asm/disassemble.h>
  32
  33 #define KVM_MAGIC_PAGE          (-4096L)
  34 #define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
  35
  36 #define KVM_MASK_RT             0x03e00000
  37
  38 static bool kvm_patching_worked = true;
  39
  40 static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
  41 {
  42         *inst = new_inst;
  43         flush_icache_range((ulong)inst, (ulong)inst + 4);
  44 }
  45
  46 static void kvm_map_magic_page(void *data)
  47 {
  48         kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE,
  49                        KVM_MAGIC_PAGE,  /* Physical Address */
  50                        KVM_MAGIC_PAGE); /* Effective Address */
  51 }
  52
  53 static void kvm_check_ins(u32 *inst)
  54 {
  55         u32 _inst = *inst;
  56         u32 inst_no_rt = _inst & ~KVM_MASK_RT;
  57         u32 inst_rt = _inst & KVM_MASK_RT;
  58
  59         switch (inst_no_rt) {
  60         }
  61
  62         switch (_inst) {
  63         }
  64 }
  65
  66 static void kvm_use_magic_page(void)
  67 {
  68         u32 *p;
  69         u32 *start, *end;
  70         u32 tmp;
  71
  72         /* Tell the host to map the magic page to -4096 on all CPUs */
  73         on_each_cpu(kvm_map_magic_page, NULL, 1);
  74
  75         /* Quick self-test to see if the mapping works */
  76         if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
  77                 kvm_patching_worked = false;
  78                 return;
  79         }
  80
  81         /* Now loop through all code and find instructions */
  82         start = (void*)_stext;
  83         end = (void*)_etext;
  84
  85         for (p = start; p < end; p++)
  86                 kvm_check_ins(p);
  87
  88         printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
  89                          kvm_patching_worked ? "worked" : "failed");
  90 }
  91
  92 unsigned long kvm_hypercall(unsigned long *in,
  93                             unsigned long *out,
  94                             unsigned long nr)
  95 {
  96         unsigned long register r0 asm("r0");
  97         unsigned long register r3 asm("r3") = in[0];
  98         unsigned long register r4 asm("r4") = in[1];
  99         unsigned long register r5 asm("r5") = in[2];
 100         unsigned long register r6 asm("r6") = in[3];
 101         unsigned long register r7 asm("r7") = in[4];
 102         unsigned long register r8 asm("r8") = in[5];
 103         unsigned long register r9 asm("r9") = in[6];
 104         unsigned long register r10 asm("r10") = in[7];
 105         unsigned long register r11 asm("r11") = nr;
 106         unsigned long register r12 asm("r12");
 107
 108         asm volatile("bl        kvm_hypercall_start"
 109                      : "=r"(r0), "=r"(r3), "=r"(r4), "=r"(r5), "=r"(r6),
 110                        "=r"(r7), "=r"(r8), "=r"(r9), "=r"(r10), "=r"(r11),
 111                        "=r"(r12)
 112                      : "r"(r3), "r"(r4), "r"(r5), "r"(r6), "r"(r7), "r"(r8),
 113                        "r"(r9), "r"(r10), "r"(r11)
 114                      : "memory", "cc", "xer", "ctr", "lr");
 115
 116         out[0] = r4;
 117         out[1] = r5;
 118         out[2] = r6;
 119         out[3] = r7;
 120         out[4] = r8;
 121         out[5] = r9;
 122         out[6] = r10;
 123         out[7] = r11;
 124
 125         return r3;
 126 }
 127 EXPORT_SYMBOL_GPL(kvm_hypercall);
 128
 129 static int kvm_para_setup(void)
 130 {
 131         extern u32 kvm_hypercall_start;
 132         struct device_node *hyper_node;
 133         u32 *insts;
 134         int len, i;
 135
 136         hyper_node = of_find_node_by_path("/hypervisor");
 137         if (!hyper_node)
 138                 return -1;
 139
 140         insts = (u32*)of_get_property(hyper_node, "hcall-instructions", &len);
 141         if (len % 4)
 142                 return -1;
 143         if (len > (4 * 4))
 144                 return -1;
 145
 146         for (i = 0; i < (len / 4); i++)
 147                 kvm_patch_ins(&(&kvm_hypercall_start)[i], insts[i]);
 148
 149         return 0;
 150 }
 151
 152 static int __init kvm_guest_init(void)
 153 {
 154         if (!kvm_para_available())
 155                 return 0;
 156
 157         if (kvm_para_setup())
 158                 return 0;
 159
 160         if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE))
 161                 kvm_use_magic_page();
 162
 163         return 0;
 164 }
 165
 166 postcore_initcall(kvm_guest_init);