arch/powerpc/kvm/44x_tlb.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License, version 2, as
   4  * published by the Free Software Foundation.
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  * GNU General Public License for more details.
  10  *
  11  * You should have received a copy of the GNU General Public License
  12  * along with this program; if not, write to the Free Software
  13  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  14  *
  15  * Copyright IBM Corp. 2007
  16  *
  17  * Authors: Hollis Blanchard <hollisb@us.ibm.com>
  18  */
  19
  20 #include <linux/types.h>
  21 #include <linux/string.h>
  22 #include <linux/kvm_host.h>
  23 #include <linux/highmem.h>
  24 #include <asm/mmu-44x.h>
  25 #include <asm/kvm_ppc.h>
  26
  27 #include "44x_tlb.h"
  28
  29 #define PPC44x_TLB_USER_PERM_MASK (PPC44x_TLB_UX|PPC44x_TLB_UR|PPC44x_TLB_UW)
  30 #define PPC44x_TLB_SUPER_PERM_MASK (PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW)
  31
  32 static unsigned int kvmppc_tlb_44x_pos;
  33
  34 static u32 kvmppc_44x_tlb_shadow_attrib(u32 attrib, int usermode)
  35 {
  36         /* Mask off reserved bits. */
  37         attrib &= PPC44x_TLB_PERM_MASK|PPC44x_TLB_ATTR_MASK;
  38
  39         if (!usermode) {
  40                 /* Guest is in supervisor mode, so we need to translate guest
  41                  * supervisor permissions into user permissions. */
  42                 attrib &= ~PPC44x_TLB_USER_PERM_MASK;
  43                 attrib |= (attrib & PPC44x_TLB_SUPER_PERM_MASK) << 3;
  44         }
  45
  46         /* Make sure host can always access this memory. */
  47         attrib |= PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW;
  48
  49         return attrib;
  50 }
  51
  52 /* Search the guest TLB for a matching entry. */
  53 int kvmppc_44x_tlb_index(struct kvm_vcpu *vcpu, gva_t eaddr, unsigned int pid,
  54                          unsigned int as)
  55 {
  56         int i;
  57
  58         /* XXX Replace loop with fancy data structures. */
  59         for (i = 0; i < PPC44x_TLB_SIZE; i++) {
  60                 struct tlbe *tlbe = &vcpu->arch.guest_tlb[i];
  61                 unsigned int tid;
  62
  63                 if (eaddr < get_tlb_eaddr(tlbe))
  64                         continue;
  65
  66                 if (eaddr > get_tlb_end(tlbe))
  67                         continue;
  68
  69                 tid = get_tlb_tid(tlbe);
  70                 if (tid && (tid != pid))
  71                         continue;
  72
  73                 if (!get_tlb_v(tlbe))
  74                         continue;
  75
  76                 if (get_tlb_ts(tlbe) != as)
  77                         continue;
  78
  79                 return i;
  80         }
  81
  82         return -1;
  83 }
  84
  85 struct tlbe *kvmppc_44x_itlb_search(struct kvm_vcpu *vcpu, gva_t eaddr)
  86 {
  87         unsigned int as = !!(vcpu->arch.msr & MSR_IS);
  88         unsigned int index;
  89
  90         index = kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
  91         if (index == -1)
  92                 return NULL;
  93         return &vcpu->arch.guest_tlb[index];
  94 }
  95
  96 struct tlbe *kvmppc_44x_dtlb_search(struct kvm_vcpu *vcpu, gva_t eaddr)
  97 {
  98         unsigned int as = !!(vcpu->arch.msr & MSR_DS);
  99         unsigned int index;
 100
 101         index = kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
 102         if (index == -1)
 103                 return NULL;
 104         return &vcpu->arch.guest_tlb[index];
 105 }
 106
 107 static int kvmppc_44x_tlbe_is_writable(struct tlbe *tlbe)
 108 {
 109         return tlbe->word2 & (PPC44x_TLB_SW|PPC44x_TLB_UW);
 110 }
 111
 112 /* Must be called with mmap_sem locked for writing. */
 113 static void kvmppc_44x_shadow_release(struct kvm_vcpu *vcpu,
 114                                       unsigned int index)
 115 {
 116         struct tlbe *stlbe = &vcpu->arch.shadow_tlb[index];
 117         struct page *page = vcpu->arch.shadow_pages[index];
 118
 119         kunmap(vcpu->arch.shadow_pages[index]);
 120
 121         if (get_tlb_v(stlbe)) {
 122                 if (kvmppc_44x_tlbe_is_writable(stlbe))
 123                         kvm_release_page_dirty(page);
 124                 else
 125                         kvm_release_page_clean(page);
 126         }
 127 }
 128
 129 /* Caller must ensure that the specified guest TLB entry is safe to insert into
 130  * the shadow TLB. */
 131 void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gfn_t gfn, u64 asid,
 132                     u32 flags)
 133 {
 134         struct page *new_page;
 135         struct tlbe *stlbe;
 136         hpa_t hpaddr;
 137         unsigned int victim;
 138
 139         /* Future optimization: don't overwrite the TLB entry containing the
 140          * current PC (or stack?). */
 141         victim = kvmppc_tlb_44x_pos++;
 142         if (kvmppc_tlb_44x_pos > tlb_44x_hwater)
 143                 kvmppc_tlb_44x_pos = 0;
 144         stlbe = &vcpu->arch.shadow_tlb[victim];
 145
 146         /* Get reference to new page. */
 147         down_write(&current->mm->mmap_sem);
 148         new_page = gfn_to_page(vcpu->kvm, gfn);
 149         if (is_error_page(new_page)) {
 150                 printk(KERN_ERR "Couldn't get guest page!\n");
 151                 kvm_release_page_clean(new_page);
 152                 return;
 153         }
 154         hpaddr = page_to_phys(new_page);
 155
 156         /* Drop reference to old page. */
 157         kvmppc_44x_shadow_release(vcpu, victim);
 158         up_write(&current->mm->mmap_sem);
 159
 160         vcpu->arch.shadow_pages[victim] = new_page;
 161
 162         /* XXX Make sure (va, size) doesn't overlap any other
 163          * entries. 440x6 user manual says the result would be
 164          * "undefined." */
 165
 166         /* XXX what about AS? */
 167
 168         stlbe->tid = asid & 0xff;
 169
 170         /* Force TS=1 for all guest mappings. */
 171         /* For now we hardcode 4KB mappings, but it will be important to
 172          * use host large pages in the future. */
 173         stlbe->word0 = (gvaddr & PAGE_MASK) | PPC44x_TLB_VALID | PPC44x_TLB_TS
 174                        | PPC44x_TLB_4K;
 175
 176         stlbe->word1 = (hpaddr & 0xfffffc00) | ((hpaddr >> 32) & 0xf);
 177         stlbe->word2 = kvmppc_44x_tlb_shadow_attrib(flags,
 178                                                     vcpu->arch.msr & MSR_PR);
 179 }
 180
 181 void kvmppc_mmu_invalidate(struct kvm_vcpu *vcpu, u64 eaddr, u64 asid)
 182 {
 183         unsigned int pid = asid & 0xff;
 184         int i;
 185
 186         /* XXX Replace loop with fancy data structures. */
 187         down_write(&current->mm->mmap_sem);
 188         for (i = 0; i <= tlb_44x_hwater; i++) {
 189                 struct tlbe *stlbe = &vcpu->arch.shadow_tlb[i];
 190                 unsigned int tid;
 191
 192                 if (!get_tlb_v(stlbe))
 193                         continue;
 194
 195                 if (eaddr < get_tlb_eaddr(stlbe))
 196                         continue;
 197
 198                 if (eaddr > get_tlb_end(stlbe))
 199                         continue;
 200
 201                 tid = get_tlb_tid(stlbe);
 202                 if (tid && (tid != pid))
 203                         continue;
 204
 205                 kvmppc_44x_shadow_release(vcpu, i);
 206                 stlbe->word0 = 0;
 207         }
 208         up_write(&current->mm->mmap_sem);
 209 }
 210
 211 /* Invalidate all mappings, so that when they fault back in they will get the
 212  * proper permission bits. */
 213 void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode)
 214 {
 215         int i;
 216
 217         /* XXX Replace loop with fancy data structures. */
 218         down_write(&current->mm->mmap_sem);
 219         for (i = 0; i <= tlb_44x_hwater; i++) {
 220                 kvmppc_44x_shadow_release(vcpu, i);
 221                 vcpu->arch.shadow_tlb[i].word0 = 0;
 222         }
 223         up_write(&current->mm->mmap_sem);
 224 }