arch/x86/kernel/kvm.c

   1 /*
   2  * KVM paravirt_ops implementation
   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 as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  *
  18  * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  19  * Copyright IBM Corporation, 2007
  20  *   Authors: Anthony Liguori <aliguori@us.ibm.com>
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/kernel.h>
  25 #include <linux/kvm_para.h>
  26 #include <linux/cpu.h>
  27 #include <linux/mm.h>
  28 #include <linux/highmem.h>
  29 #include <linux/hardirq.h>
  30 #include <asm/timer.h>
  31
  32 #define MMU_QUEUE_SIZE 1024
  33
  34 struct kvm_para_state {
  35         u8 mmu_queue[MMU_QUEUE_SIZE];
  36         int mmu_queue_len;
  37         enum paravirt_lazy_mode mode;
  38 };
  39
  40 static DEFINE_PER_CPU(struct kvm_para_state, para_state);
  41
  42 static struct kvm_para_state *kvm_para_state(void)
  43 {
  44         return &per_cpu(para_state, raw_smp_processor_id());
  45 }
  46
  47 /*
  48  * No need for any "IO delay" on KVM
  49  */
  50 static void kvm_io_delay(void)
  51 {
  52 }
  53
  54 static void kvm_mmu_op(void *buffer, unsigned len)
  55 {
  56         int r;
  57         unsigned long a1, a2;
  58
  59         do {
  60                 a1 = __pa(buffer);
  61                 a2 = 0;   /* on i386 __pa() always returns <4G */
  62                 r = kvm_hypercall3(KVM_HC_MMU_OP, len, a1, a2);
  63                 buffer += r;
  64                 len -= r;
  65         } while (len);
  66 }
  67
  68 static void mmu_queue_flush(struct kvm_para_state *state)
  69 {
  70         if (state->mmu_queue_len) {
  71                 kvm_mmu_op(state->mmu_queue, state->mmu_queue_len);
  72                 state->mmu_queue_len = 0;
  73         }
  74 }
  75
  76 static void kvm_deferred_mmu_op(void *buffer, int len)
  77 {
  78         struct kvm_para_state *state = kvm_para_state();
  79
  80         if (state->mode != PARAVIRT_LAZY_MMU) {
  81                 kvm_mmu_op(buffer, len);
  82                 return;
  83         }
  84         if (state->mmu_queue_len + len > sizeof state->mmu_queue)
  85                 mmu_queue_flush(state);
  86         memcpy(state->mmu_queue + state->mmu_queue_len, buffer, len);
  87         state->mmu_queue_len += len;
  88 }
  89
  90 static void kvm_mmu_write(void *dest, u64 val)
  91 {
  92         __u64 pte_phys;
  93         struct kvm_mmu_op_write_pte wpte;
  94
  95 #ifdef CONFIG_HIGHPTE
  96         struct page *page;
  97         unsigned long dst = (unsigned long) dest;
  98
  99         page = kmap_atomic_to_page(dest);
 100         pte_phys = page_to_pfn(page);
 101         pte_phys <<= PAGE_SHIFT;
 102         pte_phys += (dst & ~(PAGE_MASK));
 103 #else
 104         pte_phys = (unsigned long)__pa(dest);
 105 #endif
 106         wpte.header.op = KVM_MMU_OP_WRITE_PTE;
 107         wpte.pte_val = val;
 108         wpte.pte_phys = pte_phys;
 109
 110         kvm_deferred_mmu_op(&wpte, sizeof wpte);
 111 }
 112
 113 /*
 114  * We only need to hook operations that are MMU writes.  We hook these so that
 115  * we can use lazy MMU mode to batch these operations.  We could probably
 116  * improve the performance of the host code if we used some of the information
 117  * here to simplify processing of batched writes.
 118  */
 119 static void kvm_set_pte(pte_t *ptep, pte_t pte)
 120 {
 121         kvm_mmu_write(ptep, pte_val(pte));
 122 }
 123
 124 static void kvm_set_pte_at(struct mm_struct *mm, unsigned long addr,
 125                            pte_t *ptep, pte_t pte)
 126 {
 127         kvm_mmu_write(ptep, pte_val(pte));
 128 }
 129
 130 static void kvm_set_pmd(pmd_t *pmdp, pmd_t pmd)
 131 {
 132         kvm_mmu_write(pmdp, pmd_val(pmd));
 133 }
 134
 135 #if PAGETABLE_LEVELS >= 3
 136 #ifdef CONFIG_X86_PAE
 137 static void kvm_set_pte_atomic(pte_t *ptep, pte_t pte)
 138 {
 139         kvm_mmu_write(ptep, pte_val(pte));
 140 }
 141
 142 static void kvm_pte_clear(struct mm_struct *mm,
 143                           unsigned long addr, pte_t *ptep)
 144 {
 145         kvm_mmu_write(ptep, 0);
 146 }
 147
 148 static void kvm_pmd_clear(pmd_t *pmdp)
 149 {
 150         kvm_mmu_write(pmdp, 0);
 151 }
 152 #endif
 153
 154 static void kvm_set_pud(pud_t *pudp, pud_t pud)
 155 {
 156         kvm_mmu_write(pudp, pud_val(pud));
 157 }
 158
 159 #if PAGETABLE_LEVELS == 4
 160 static void kvm_set_pgd(pgd_t *pgdp, pgd_t pgd)
 161 {
 162         kvm_mmu_write(pgdp, pgd_val(pgd));
 163 }
 164 #endif
 165 #endif /* PAGETABLE_LEVELS >= 3 */
 166
 167 static void kvm_flush_tlb(void)
 168 {
 169         struct kvm_mmu_op_flush_tlb ftlb = {
 170                 .header.op = KVM_MMU_OP_FLUSH_TLB,
 171         };
 172
 173         kvm_deferred_mmu_op(&ftlb, sizeof ftlb);
 174 }
 175
 176 static void kvm_release_pt(unsigned long pfn)
 177 {
 178         struct kvm_mmu_op_release_pt rpt = {
 179                 .header.op = KVM_MMU_OP_RELEASE_PT,
 180                 .pt_phys = (u64)pfn << PAGE_SHIFT,
 181         };
 182
 183         kvm_mmu_op(&rpt, sizeof rpt);
 184 }
 185
 186 static void kvm_enter_lazy_mmu(void)
 187 {
 188         struct kvm_para_state *state = kvm_para_state();
 189
 190         paravirt_enter_lazy_mmu();
 191         state->mode = paravirt_get_lazy_mode();
 192 }
 193
 194 static void kvm_leave_lazy_mmu(void)
 195 {
 196         struct kvm_para_state *state = kvm_para_state();
 197
 198         mmu_queue_flush(state);
 199         paravirt_leave_lazy_mmu();
 200         state->mode = paravirt_get_lazy_mode();
 201 }
 202
 203 static void paravirt_ops_setup(void)
 204 {
 205         pv_info.name = "KVM";
 206         pv_info.paravirt_enabled = 1;
 207
 208         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 209                 pv_cpu_ops.io_delay = kvm_io_delay;
 210
 211         if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
 212                 pv_mmu_ops.set_pte = kvm_set_pte;
 213                 pv_mmu_ops.set_pte_at = kvm_set_pte_at;
 214                 pv_mmu_ops.set_pmd = kvm_set_pmd;
 215 #if PAGETABLE_LEVELS >= 3
 216 #ifdef CONFIG_X86_PAE
 217                 pv_mmu_ops.set_pte_atomic = kvm_set_pte_atomic;
 218                 pv_mmu_ops.pte_clear = kvm_pte_clear;
 219                 pv_mmu_ops.pmd_clear = kvm_pmd_clear;
 220 #endif
 221                 pv_mmu_ops.set_pud = kvm_set_pud;
 222 #if PAGETABLE_LEVELS == 4
 223                 pv_mmu_ops.set_pgd = kvm_set_pgd;
 224 #endif
 225 #endif
 226                 pv_mmu_ops.flush_tlb_user = kvm_flush_tlb;
 227                 pv_mmu_ops.release_pte = kvm_release_pt;
 228                 pv_mmu_ops.release_pmd = kvm_release_pt;
 229                 pv_mmu_ops.release_pud = kvm_release_pt;
 230
 231                 pv_mmu_ops.lazy_mode.enter = kvm_enter_lazy_mmu;
 232                 pv_mmu_ops.lazy_mode.leave = kvm_leave_lazy_mmu;
 233         }
 234 #ifdef CONFIG_X86_IO_APIC
 235         no_timer_check = 1;
 236 #endif
 237 }
 238
 239 void __init kvm_guest_init(void)
 240 {
 241         if (!kvm_para_available())
 242                 return;
 243
 244         paravirt_ops_setup();
 245 }