Rusty Russell | f938d2c | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1 | /*P:800 Interrupts (traps) are complicated enough to earn their own file. |
| 2 | * There are three classes of interrupts: |
| 3 | * |
| 4 | * 1) Real hardware interrupts which occur while we're running the Guest, |
| 5 | * 2) Interrupts for virtual devices attached to the Guest, and |
| 6 | * 3) Traps and faults from the Guest. |
| 7 | * |
| 8 | * Real hardware interrupts must be delivered to the Host, not the Guest. |
| 9 | * Virtual interrupts must be delivered to the Guest, but we make them look |
| 10 | * just like real hardware would deliver them. Traps from the Guest can be set |
| 11 | * up to go directly back into the Guest, but sometimes the Host wants to see |
| 12 | * them first, so we also have a way of "reflecting" them into the Guest as if |
| 13 | * they had been delivered to it directly. :*/ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 14 | #include <linux/uaccess.h> |
| 15 | #include "lg.h" |
| 16 | |
| 17 | static unsigned long idt_address(u32 lo, u32 hi) |
| 18 | { |
| 19 | return (lo & 0x0000FFFF) | (hi & 0xFFFF0000); |
| 20 | } |
| 21 | |
| 22 | static int idt_type(u32 lo, u32 hi) |
| 23 | { |
| 24 | return (hi >> 8) & 0xF; |
| 25 | } |
| 26 | |
| 27 | static int idt_present(u32 lo, u32 hi) |
| 28 | { |
| 29 | return (hi & 0x8000); |
| 30 | } |
| 31 | |
| 32 | static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val) |
| 33 | { |
| 34 | *gstack -= 4; |
| 35 | lgwrite_u32(lg, *gstack, val); |
| 36 | } |
| 37 | |
| 38 | static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) |
| 39 | { |
| 40 | unsigned long gstack; |
| 41 | u32 eflags, ss, irq_enable; |
| 42 | |
| 43 | /* If they want a ring change, we use new stack and push old ss/esp */ |
| 44 | if ((lg->regs->ss&0x3) != GUEST_PL) { |
| 45 | gstack = guest_pa(lg, lg->esp1); |
| 46 | ss = lg->ss1; |
| 47 | push_guest_stack(lg, &gstack, lg->regs->ss); |
| 48 | push_guest_stack(lg, &gstack, lg->regs->esp); |
| 49 | } else { |
| 50 | gstack = guest_pa(lg, lg->regs->esp); |
| 51 | ss = lg->regs->ss; |
| 52 | } |
| 53 | |
Rusty Russell | e5faff4 | 2007-07-20 22:11:13 +1000 | [diff] [blame] | 54 | /* We use IF bit in eflags to indicate whether irqs were enabled |
| 55 | (it's always 1, since irqs are enabled when guest is running). */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 56 | eflags = lg->regs->eflags; |
Rusty Russell | e5faff4 | 2007-07-20 22:11:13 +1000 | [diff] [blame] | 57 | if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0 |
| 58 | && !(irq_enable & X86_EFLAGS_IF)) |
| 59 | eflags &= ~X86_EFLAGS_IF; |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 60 | |
| 61 | push_guest_stack(lg, &gstack, eflags); |
| 62 | push_guest_stack(lg, &gstack, lg->regs->cs); |
| 63 | push_guest_stack(lg, &gstack, lg->regs->eip); |
| 64 | |
| 65 | if (has_err) |
| 66 | push_guest_stack(lg, &gstack, lg->regs->errcode); |
| 67 | |
| 68 | /* Change the real stack so switcher returns to trap handler */ |
| 69 | lg->regs->ss = ss; |
| 70 | lg->regs->esp = gstack + lg->page_offset; |
| 71 | lg->regs->cs = (__KERNEL_CS|GUEST_PL); |
| 72 | lg->regs->eip = idt_address(lo, hi); |
| 73 | |
| 74 | /* Disable interrupts for an interrupt gate. */ |
| 75 | if (idt_type(lo, hi) == 0xE) |
| 76 | if (put_user(0, &lg->lguest_data->irq_enabled)) |
| 77 | kill_guest(lg, "Disabling interrupts"); |
| 78 | } |
| 79 | |
| 80 | void maybe_do_interrupt(struct lguest *lg) |
| 81 | { |
| 82 | unsigned int irq; |
| 83 | DECLARE_BITMAP(blk, LGUEST_IRQS); |
| 84 | struct desc_struct *idt; |
| 85 | |
| 86 | if (!lg->lguest_data) |
| 87 | return; |
| 88 | |
| 89 | /* Mask out any interrupts they have blocked. */ |
| 90 | if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts, |
| 91 | sizeof(blk))) |
| 92 | return; |
| 93 | |
| 94 | bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS); |
| 95 | |
| 96 | irq = find_first_bit(blk, LGUEST_IRQS); |
| 97 | if (irq >= LGUEST_IRQS) |
| 98 | return; |
| 99 | |
| 100 | if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end) |
| 101 | return; |
| 102 | |
| 103 | /* If they're halted, we re-enable interrupts. */ |
| 104 | if (lg->halted) { |
| 105 | /* Re-enable interrupts. */ |
| 106 | if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled)) |
| 107 | kill_guest(lg, "Re-enabling interrupts"); |
| 108 | lg->halted = 0; |
| 109 | } else { |
| 110 | /* Maybe they have interrupts disabled? */ |
| 111 | u32 irq_enabled; |
| 112 | if (get_user(irq_enabled, &lg->lguest_data->irq_enabled)) |
| 113 | irq_enabled = 0; |
| 114 | if (!irq_enabled) |
| 115 | return; |
| 116 | } |
| 117 | |
| 118 | idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq]; |
| 119 | if (idt_present(idt->a, idt->b)) { |
| 120 | clear_bit(irq, lg->irqs_pending); |
| 121 | set_guest_interrupt(lg, idt->a, idt->b, 0); |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | static int has_err(unsigned int trap) |
| 126 | { |
| 127 | return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17); |
| 128 | } |
| 129 | |
| 130 | int deliver_trap(struct lguest *lg, unsigned int num) |
| 131 | { |
| 132 | u32 lo = lg->idt[num].a, hi = lg->idt[num].b; |
| 133 | |
| 134 | if (!idt_present(lo, hi)) |
| 135 | return 0; |
| 136 | set_guest_interrupt(lg, lo, hi, has_err(num)); |
| 137 | return 1; |
| 138 | } |
| 139 | |
| 140 | static int direct_trap(const struct lguest *lg, |
| 141 | const struct desc_struct *trap, |
| 142 | unsigned int num) |
| 143 | { |
| 144 | /* Hardware interrupts don't go to guest (except syscall). */ |
| 145 | if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR) |
| 146 | return 0; |
| 147 | |
| 148 | /* We intercept page fault (demand shadow paging & cr2 saving) |
| 149 | protection fault (in/out emulation) and device not |
| 150 | available (TS handling), and hypercall */ |
| 151 | if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY) |
| 152 | return 0; |
| 153 | |
| 154 | /* Interrupt gates (0xE) or not present (0x0) can't go direct. */ |
| 155 | return idt_type(trap->a, trap->b) == 0xF; |
| 156 | } |
| 157 | |
| 158 | void pin_stack_pages(struct lguest *lg) |
| 159 | { |
| 160 | unsigned int i; |
| 161 | |
| 162 | for (i = 0; i < lg->stack_pages; i++) |
| 163 | pin_page(lg, lg->esp1 - i * PAGE_SIZE); |
| 164 | } |
| 165 | |
| 166 | void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages) |
| 167 | { |
| 168 | /* You cannot have a stack segment with priv level 0. */ |
| 169 | if ((seg & 0x3) != GUEST_PL) |
| 170 | kill_guest(lg, "bad stack segment %i", seg); |
| 171 | if (pages > 2) |
| 172 | kill_guest(lg, "bad stack pages %u", pages); |
| 173 | lg->ss1 = seg; |
| 174 | lg->esp1 = esp; |
| 175 | lg->stack_pages = pages; |
| 176 | pin_stack_pages(lg); |
| 177 | } |
| 178 | |
| 179 | /* Set up trap in IDT. */ |
| 180 | static void set_trap(struct lguest *lg, struct desc_struct *trap, |
| 181 | unsigned int num, u32 lo, u32 hi) |
| 182 | { |
| 183 | u8 type = idt_type(lo, hi); |
| 184 | |
| 185 | if (!idt_present(lo, hi)) { |
| 186 | trap->a = trap->b = 0; |
| 187 | return; |
| 188 | } |
| 189 | |
| 190 | if (type != 0xE && type != 0xF) |
| 191 | kill_guest(lg, "bad IDT type %i", type); |
| 192 | |
| 193 | trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF); |
| 194 | trap->b = (hi&0xFFFFEF00); |
| 195 | } |
| 196 | |
| 197 | void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi) |
| 198 | { |
| 199 | /* Guest never handles: NMI, doublefault, hypercall, spurious irq. */ |
| 200 | if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY) |
| 201 | return; |
| 202 | |
| 203 | lg->changed |= CHANGED_IDT; |
| 204 | if (num < ARRAY_SIZE(lg->idt)) |
| 205 | set_trap(lg, &lg->idt[num], num, lo, hi); |
| 206 | else if (num == SYSCALL_VECTOR) |
| 207 | set_trap(lg, &lg->syscall_idt, num, lo, hi); |
| 208 | } |
| 209 | |
| 210 | static void default_idt_entry(struct desc_struct *idt, |
| 211 | int trap, |
| 212 | const unsigned long handler) |
| 213 | { |
| 214 | u32 flags = 0x8e00; |
| 215 | |
| 216 | /* They can't "int" into any of them except hypercall. */ |
| 217 | if (trap == LGUEST_TRAP_ENTRY) |
| 218 | flags |= (GUEST_PL << 13); |
| 219 | |
| 220 | idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF); |
| 221 | idt->b = (handler&0xFFFF0000) | flags; |
| 222 | } |
| 223 | |
| 224 | void setup_default_idt_entries(struct lguest_ro_state *state, |
| 225 | const unsigned long *def) |
| 226 | { |
| 227 | unsigned int i; |
| 228 | |
| 229 | for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++) |
| 230 | default_idt_entry(&state->guest_idt[i], i, def[i]); |
| 231 | } |
| 232 | |
| 233 | void copy_traps(const struct lguest *lg, struct desc_struct *idt, |
| 234 | const unsigned long *def) |
| 235 | { |
| 236 | unsigned int i; |
| 237 | |
| 238 | /* All hardware interrupts are same whatever the guest: only the |
| 239 | * traps might be different. */ |
| 240 | for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) { |
| 241 | if (direct_trap(lg, &lg->idt[i], i)) |
| 242 | idt[i] = lg->idt[i]; |
| 243 | else |
| 244 | default_idt_entry(&idt[i], i, def[i]); |
| 245 | } |
| 246 | i = SYSCALL_VECTOR; |
| 247 | if (direct_trap(lg, &lg->syscall_idt, i)) |
| 248 | idt[i] = lg->syscall_idt; |
| 249 | else |
| 250 | default_idt_entry(&idt[i], i, def[i]); |
| 251 | } |
| 252 | |
| 253 | void guest_set_clockevent(struct lguest *lg, unsigned long delta) |
| 254 | { |
| 255 | ktime_t expires; |
| 256 | |
| 257 | if (unlikely(delta == 0)) { |
| 258 | /* Clock event device is shutting down. */ |
| 259 | hrtimer_cancel(&lg->hrt); |
| 260 | return; |
| 261 | } |
| 262 | |
| 263 | expires = ktime_add_ns(ktime_get_real(), delta); |
| 264 | hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS); |
| 265 | } |
| 266 | |
| 267 | static enum hrtimer_restart clockdev_fn(struct hrtimer *timer) |
| 268 | { |
| 269 | struct lguest *lg = container_of(timer, struct lguest, hrt); |
| 270 | |
| 271 | set_bit(0, lg->irqs_pending); |
| 272 | if (lg->halted) |
| 273 | wake_up_process(lg->tsk); |
| 274 | return HRTIMER_NORESTART; |
| 275 | } |
| 276 | |
| 277 | void init_clockdev(struct lguest *lg) |
| 278 | { |
| 279 | hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
| 280 | lg->hrt.function = clockdev_fn; |
| 281 | } |