Commit | Line | Data |
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f938d2c8 RR |
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. :*/ | |
d7e28ffe | 14 | #include <linux/uaccess.h> |
c18acd73 RR |
15 | #include <linux/interrupt.h> |
16 | #include <linux/module.h> | |
d7e28ffe RR |
17 | #include "lg.h" |
18 | ||
c18acd73 RR |
19 | /* Allow Guests to use a non-128 (ie. non-Linux) syscall trap. */ |
20 | static unsigned int syscall_vector = SYSCALL_VECTOR; | |
21 | module_param(syscall_vector, uint, 0444); | |
22 | ||
bff672e6 | 23 | /* The address of the interrupt handler is split into two bits: */ |
d7e28ffe RR |
24 | static unsigned long idt_address(u32 lo, u32 hi) |
25 | { | |
26 | return (lo & 0x0000FFFF) | (hi & 0xFFFF0000); | |
27 | } | |
28 | ||
bff672e6 RR |
29 | /* The "type" of the interrupt handler is a 4 bit field: we only support a |
30 | * couple of types. */ | |
d7e28ffe RR |
31 | static int idt_type(u32 lo, u32 hi) |
32 | { | |
33 | return (hi >> 8) & 0xF; | |
34 | } | |
35 | ||
bff672e6 | 36 | /* An IDT entry can't be used unless the "present" bit is set. */ |
d7e28ffe RR |
37 | static int idt_present(u32 lo, u32 hi) |
38 | { | |
39 | return (hi & 0x8000); | |
40 | } | |
41 | ||
bff672e6 RR |
42 | /* We need a helper to "push" a value onto the Guest's stack, since that's a |
43 | * big part of what delivering an interrupt does. */ | |
d7e28ffe RR |
44 | static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val) |
45 | { | |
bff672e6 | 46 | /* Stack grows upwards: move stack then write value. */ |
d7e28ffe RR |
47 | *gstack -= 4; |
48 | lgwrite_u32(lg, *gstack, val); | |
49 | } | |
50 | ||
bff672e6 RR |
51 | /*H:210 The set_guest_interrupt() routine actually delivers the interrupt or |
52 | * trap. The mechanics of delivering traps and interrupts to the Guest are the | |
53 | * same, except some traps have an "error code" which gets pushed onto the | |
54 | * stack as well: the caller tells us if this is one. | |
55 | * | |
56 | * "lo" and "hi" are the two parts of the Interrupt Descriptor Table for this | |
57 | * interrupt or trap. It's split into two parts for traditional reasons: gcc | |
58 | * on i386 used to be frightened by 64 bit numbers. | |
59 | * | |
60 | * We set up the stack just like the CPU does for a real interrupt, so it's | |
61 | * identical for the Guest (and the standard "iret" instruction will undo | |
62 | * it). */ | |
d7e28ffe RR |
63 | static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) |
64 | { | |
65 | unsigned long gstack; | |
66 | u32 eflags, ss, irq_enable; | |
67 | ||
bff672e6 RR |
68 | /* There are two cases for interrupts: one where the Guest is already |
69 | * in the kernel, and a more complex one where the Guest is in | |
70 | * userspace. We check the privilege level to find out. */ | |
d7e28ffe | 71 | if ((lg->regs->ss&0x3) != GUEST_PL) { |
bff672e6 RR |
72 | /* The Guest told us their kernel stack with the SET_STACK |
73 | * hypercall: both the virtual address and the segment */ | |
d7e28ffe RR |
74 | gstack = guest_pa(lg, lg->esp1); |
75 | ss = lg->ss1; | |
bff672e6 RR |
76 | /* We push the old stack segment and pointer onto the new |
77 | * stack: when the Guest does an "iret" back from the interrupt | |
78 | * handler the CPU will notice they're dropping privilege | |
79 | * levels and expect these here. */ | |
d7e28ffe RR |
80 | push_guest_stack(lg, &gstack, lg->regs->ss); |
81 | push_guest_stack(lg, &gstack, lg->regs->esp); | |
82 | } else { | |
bff672e6 | 83 | /* We're staying on the same Guest (kernel) stack. */ |
d7e28ffe RR |
84 | gstack = guest_pa(lg, lg->regs->esp); |
85 | ss = lg->regs->ss; | |
86 | } | |
87 | ||
bff672e6 RR |
88 | /* Remember that we never let the Guest actually disable interrupts, so |
89 | * the "Interrupt Flag" bit is always set. We copy that bit from the | |
90 | * Guest's "irq_enabled" field into the eflags word: the Guest copies | |
91 | * it back in "lguest_iret". */ | |
d7e28ffe | 92 | eflags = lg->regs->eflags; |
e5faff45 RR |
93 | if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0 |
94 | && !(irq_enable & X86_EFLAGS_IF)) | |
95 | eflags &= ~X86_EFLAGS_IF; | |
d7e28ffe | 96 | |
bff672e6 RR |
97 | /* An interrupt is expected to push three things on the stack: the old |
98 | * "eflags" word, the old code segment, and the old instruction | |
99 | * pointer. */ | |
d7e28ffe RR |
100 | push_guest_stack(lg, &gstack, eflags); |
101 | push_guest_stack(lg, &gstack, lg->regs->cs); | |
102 | push_guest_stack(lg, &gstack, lg->regs->eip); | |
103 | ||
bff672e6 | 104 | /* For the six traps which supply an error code, we push that, too. */ |
d7e28ffe RR |
105 | if (has_err) |
106 | push_guest_stack(lg, &gstack, lg->regs->errcode); | |
107 | ||
bff672e6 RR |
108 | /* Now we've pushed all the old state, we change the stack, the code |
109 | * segment and the address to execute. */ | |
d7e28ffe RR |
110 | lg->regs->ss = ss; |
111 | lg->regs->esp = gstack + lg->page_offset; | |
112 | lg->regs->cs = (__KERNEL_CS|GUEST_PL); | |
113 | lg->regs->eip = idt_address(lo, hi); | |
114 | ||
bff672e6 RR |
115 | /* There are two kinds of interrupt handlers: 0xE is an "interrupt |
116 | * gate" which expects interrupts to be disabled on entry. */ | |
d7e28ffe RR |
117 | if (idt_type(lo, hi) == 0xE) |
118 | if (put_user(0, &lg->lguest_data->irq_enabled)) | |
119 | kill_guest(lg, "Disabling interrupts"); | |
120 | } | |
121 | ||
bff672e6 RR |
122 | /*H:200 |
123 | * Virtual Interrupts. | |
124 | * | |
125 | * maybe_do_interrupt() gets called before every entry to the Guest, to see if | |
126 | * we should divert the Guest to running an interrupt handler. */ | |
d7e28ffe RR |
127 | void maybe_do_interrupt(struct lguest *lg) |
128 | { | |
129 | unsigned int irq; | |
130 | DECLARE_BITMAP(blk, LGUEST_IRQS); | |
131 | struct desc_struct *idt; | |
132 | ||
bff672e6 | 133 | /* If the Guest hasn't even initialized yet, we can do nothing. */ |
d7e28ffe RR |
134 | if (!lg->lguest_data) |
135 | return; | |
136 | ||
bff672e6 RR |
137 | /* Take our "irqs_pending" array and remove any interrupts the Guest |
138 | * wants blocked: the result ends up in "blk". */ | |
d7e28ffe RR |
139 | if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts, |
140 | sizeof(blk))) | |
141 | return; | |
142 | ||
143 | bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS); | |
144 | ||
bff672e6 | 145 | /* Find the first interrupt. */ |
d7e28ffe | 146 | irq = find_first_bit(blk, LGUEST_IRQS); |
bff672e6 | 147 | /* None? Nothing to do */ |
d7e28ffe RR |
148 | if (irq >= LGUEST_IRQS) |
149 | return; | |
150 | ||
bff672e6 RR |
151 | /* They may be in the middle of an iret, where they asked us never to |
152 | * deliver interrupts. */ | |
d7e28ffe RR |
153 | if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end) |
154 | return; | |
155 | ||
bff672e6 | 156 | /* If they're halted, interrupts restart them. */ |
d7e28ffe RR |
157 | if (lg->halted) { |
158 | /* Re-enable interrupts. */ | |
159 | if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled)) | |
160 | kill_guest(lg, "Re-enabling interrupts"); | |
161 | lg->halted = 0; | |
162 | } else { | |
bff672e6 | 163 | /* Otherwise we check if they have interrupts disabled. */ |
d7e28ffe RR |
164 | u32 irq_enabled; |
165 | if (get_user(irq_enabled, &lg->lguest_data->irq_enabled)) | |
166 | irq_enabled = 0; | |
167 | if (!irq_enabled) | |
168 | return; | |
169 | } | |
170 | ||
bff672e6 RR |
171 | /* Look at the IDT entry the Guest gave us for this interrupt. The |
172 | * first 32 (FIRST_EXTERNAL_VECTOR) entries are for traps, so we skip | |
173 | * over them. */ | |
625efab1 | 174 | idt = &lg->arch.idt[FIRST_EXTERNAL_VECTOR+irq]; |
bff672e6 | 175 | /* If they don't have a handler (yet?), we just ignore it */ |
d7e28ffe | 176 | if (idt_present(idt->a, idt->b)) { |
bff672e6 | 177 | /* OK, mark it no longer pending and deliver it. */ |
d7e28ffe | 178 | clear_bit(irq, lg->irqs_pending); |
bff672e6 RR |
179 | /* set_guest_interrupt() takes the interrupt descriptor and a |
180 | * flag to say whether this interrupt pushes an error code onto | |
181 | * the stack as well: virtual interrupts never do. */ | |
d7e28ffe RR |
182 | set_guest_interrupt(lg, idt->a, idt->b, 0); |
183 | } | |
6c8dca5d RR |
184 | |
185 | /* Every time we deliver an interrupt, we update the timestamp in the | |
186 | * Guest's lguest_data struct. It would be better for the Guest if we | |
187 | * did this more often, but it can actually be quite slow: doing it | |
188 | * here is a compromise which means at least it gets updated every | |
189 | * timer interrupt. */ | |
190 | write_timestamp(lg); | |
d7e28ffe | 191 | } |
c18acd73 RR |
192 | /*:*/ |
193 | ||
194 | /* Linux uses trap 128 for system calls. Plan9 uses 64, and Ron Minnich sent | |
195 | * me a patch, so we support that too. It'd be a big step for lguest if half | |
196 | * the Plan 9 user base were to start using it. | |
197 | * | |
198 | * Actually now I think of it, it's possible that Ron *is* half the Plan 9 | |
199 | * userbase. Oh well. */ | |
200 | static bool could_be_syscall(unsigned int num) | |
201 | { | |
202 | /* Normal Linux SYSCALL_VECTOR or reserved vector? */ | |
203 | return num == SYSCALL_VECTOR || num == syscall_vector; | |
204 | } | |
205 | ||
206 | /* The syscall vector it wants must be unused by Host. */ | |
207 | bool check_syscall_vector(struct lguest *lg) | |
208 | { | |
209 | u32 vector; | |
210 | ||
211 | if (get_user(vector, &lg->lguest_data->syscall_vec)) | |
212 | return false; | |
213 | ||
214 | return could_be_syscall(vector); | |
215 | } | |
216 | ||
217 | int init_interrupts(void) | |
218 | { | |
219 | /* If they want some strange system call vector, reserve it now */ | |
220 | if (syscall_vector != SYSCALL_VECTOR | |
221 | && test_and_set_bit(syscall_vector, used_vectors)) { | |
222 | printk("lg: couldn't reserve syscall %u\n", syscall_vector); | |
223 | return -EBUSY; | |
224 | } | |
225 | return 0; | |
226 | } | |
227 | ||
228 | void free_interrupts(void) | |
229 | { | |
230 | if (syscall_vector != SYSCALL_VECTOR) | |
231 | clear_bit(syscall_vector, used_vectors); | |
232 | } | |
d7e28ffe | 233 | |
bff672e6 RR |
234 | /*H:220 Now we've got the routines to deliver interrupts, delivering traps |
235 | * like page fault is easy. The only trick is that Intel decided that some | |
236 | * traps should have error codes: */ | |
d7e28ffe RR |
237 | static int has_err(unsigned int trap) |
238 | { | |
239 | return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17); | |
240 | } | |
241 | ||
bff672e6 | 242 | /* deliver_trap() returns true if it could deliver the trap. */ |
d7e28ffe RR |
243 | int deliver_trap(struct lguest *lg, unsigned int num) |
244 | { | |
0d027c01 RR |
245 | /* Trap numbers are always 8 bit, but we set an impossible trap number |
246 | * for traps inside the Switcher, so check that here. */ | |
625efab1 | 247 | if (num >= ARRAY_SIZE(lg->arch.idt)) |
0d027c01 | 248 | return 0; |
d7e28ffe | 249 | |
bff672e6 RR |
250 | /* Early on the Guest hasn't set the IDT entries (or maybe it put a |
251 | * bogus one in): if we fail here, the Guest will be killed. */ | |
625efab1 | 252 | if (!idt_present(lg->arch.idt[num].a, lg->arch.idt[num].b)) |
d7e28ffe | 253 | return 0; |
625efab1 | 254 | set_guest_interrupt(lg, lg->arch.idt[num].a, lg->arch.idt[num].b, has_err(num)); |
d7e28ffe RR |
255 | return 1; |
256 | } | |
257 | ||
bff672e6 RR |
258 | /*H:250 Here's the hard part: returning to the Host every time a trap happens |
259 | * and then calling deliver_trap() and re-entering the Guest is slow. | |
260 | * Particularly because Guest userspace system calls are traps (trap 128). | |
261 | * | |
262 | * So we'd like to set up the IDT to tell the CPU to deliver traps directly | |
263 | * into the Guest. This is possible, but the complexities cause the size of | |
264 | * this file to double! However, 150 lines of code is worth writing for taking | |
265 | * system calls down from 1750ns to 270ns. Plus, if lguest didn't do it, all | |
266 | * the other hypervisors would tease it. | |
267 | * | |
56adbe9d RR |
268 | * This routine indicates if a particular trap number could be delivered |
269 | * directly. */ | |
270 | static int direct_trap(unsigned int num) | |
d7e28ffe | 271 | { |
bff672e6 RR |
272 | /* Hardware interrupts don't go to the Guest at all (except system |
273 | * call). */ | |
c18acd73 | 274 | if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num)) |
d7e28ffe RR |
275 | return 0; |
276 | ||
bff672e6 RR |
277 | /* The Host needs to see page faults (for shadow paging and to save the |
278 | * fault address), general protection faults (in/out emulation) and | |
279 | * device not available (TS handling), and of course, the hypercall | |
280 | * trap. */ | |
56adbe9d | 281 | return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY; |
d7e28ffe | 282 | } |
f56a384e RR |
283 | /*:*/ |
284 | ||
285 | /*M:005 The Guest has the ability to turn its interrupt gates into trap gates, | |
286 | * if it is careful. The Host will let trap gates can go directly to the | |
287 | * Guest, but the Guest needs the interrupts atomically disabled for an | |
288 | * interrupt gate. It can do this by pointing the trap gate at instructions | |
289 | * within noirq_start and noirq_end, where it can safely disable interrupts. */ | |
290 | ||
291 | /*M:006 The Guests do not use the sysenter (fast system call) instruction, | |
292 | * because it's hardcoded to enter privilege level 0 and so can't go direct. | |
293 | * It's about twice as fast as the older "int 0x80" system call, so it might | |
294 | * still be worthwhile to handle it in the Switcher and lcall down to the | |
295 | * Guest. The sysenter semantics are hairy tho: search for that keyword in | |
296 | * entry.S :*/ | |
d7e28ffe | 297 | |
bff672e6 RR |
298 | /*H:260 When we make traps go directly into the Guest, we need to make sure |
299 | * the kernel stack is valid (ie. mapped in the page tables). Otherwise, the | |
300 | * CPU trying to deliver the trap will fault while trying to push the interrupt | |
301 | * words on the stack: this is called a double fault, and it forces us to kill | |
302 | * the Guest. | |
303 | * | |
304 | * Which is deeply unfair, because (literally!) it wasn't the Guests' fault. */ | |
d7e28ffe RR |
305 | void pin_stack_pages(struct lguest *lg) |
306 | { | |
307 | unsigned int i; | |
308 | ||
bff672e6 RR |
309 | /* Depending on the CONFIG_4KSTACKS option, the Guest can have one or |
310 | * two pages of stack space. */ | |
d7e28ffe | 311 | for (i = 0; i < lg->stack_pages; i++) |
8057d763 RR |
312 | /* The stack grows *upwards*, so the address we're given is the |
313 | * start of the page after the kernel stack. Subtract one to | |
314 | * get back onto the first stack page, and keep subtracting to | |
315 | * get to the rest of the stack pages. */ | |
316 | pin_page(lg, lg->esp1 - 1 - i * PAGE_SIZE); | |
d7e28ffe RR |
317 | } |
318 | ||
bff672e6 RR |
319 | /* Direct traps also mean that we need to know whenever the Guest wants to use |
320 | * a different kernel stack, so we can change the IDT entries to use that | |
321 | * stack. The IDT entries expect a virtual address, so unlike most addresses | |
322 | * the Guest gives us, the "esp" (stack pointer) value here is virtual, not | |
323 | * physical. | |
324 | * | |
325 | * In Linux each process has its own kernel stack, so this happens a lot: we | |
326 | * change stacks on each context switch. */ | |
d7e28ffe RR |
327 | void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages) |
328 | { | |
bff672e6 RR |
329 | /* You are not allowd have a stack segment with privilege level 0: bad |
330 | * Guest! */ | |
d7e28ffe RR |
331 | if ((seg & 0x3) != GUEST_PL) |
332 | kill_guest(lg, "bad stack segment %i", seg); | |
bff672e6 | 333 | /* We only expect one or two stack pages. */ |
d7e28ffe RR |
334 | if (pages > 2) |
335 | kill_guest(lg, "bad stack pages %u", pages); | |
bff672e6 | 336 | /* Save where the stack is, and how many pages */ |
d7e28ffe RR |
337 | lg->ss1 = seg; |
338 | lg->esp1 = esp; | |
339 | lg->stack_pages = pages; | |
bff672e6 | 340 | /* Make sure the new stack pages are mapped */ |
d7e28ffe RR |
341 | pin_stack_pages(lg); |
342 | } | |
343 | ||
bff672e6 RR |
344 | /* All this reference to mapping stacks leads us neatly into the other complex |
345 | * part of the Host: page table handling. */ | |
346 | ||
347 | /*H:235 This is the routine which actually checks the Guest's IDT entry and | |
348 | * transfers it into our entry in "struct lguest": */ | |
d7e28ffe RR |
349 | static void set_trap(struct lguest *lg, struct desc_struct *trap, |
350 | unsigned int num, u32 lo, u32 hi) | |
351 | { | |
352 | u8 type = idt_type(lo, hi); | |
353 | ||
bff672e6 | 354 | /* We zero-out a not-present entry */ |
d7e28ffe RR |
355 | if (!idt_present(lo, hi)) { |
356 | trap->a = trap->b = 0; | |
357 | return; | |
358 | } | |
359 | ||
bff672e6 | 360 | /* We only support interrupt and trap gates. */ |
d7e28ffe RR |
361 | if (type != 0xE && type != 0xF) |
362 | kill_guest(lg, "bad IDT type %i", type); | |
363 | ||
bff672e6 RR |
364 | /* We only copy the handler address, present bit, privilege level and |
365 | * type. The privilege level controls where the trap can be triggered | |
366 | * manually with an "int" instruction. This is usually GUEST_PL, | |
367 | * except for system calls which userspace can use. */ | |
d7e28ffe RR |
368 | trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF); |
369 | trap->b = (hi&0xFFFFEF00); | |
370 | } | |
371 | ||
bff672e6 RR |
372 | /*H:230 While we're here, dealing with delivering traps and interrupts to the |
373 | * Guest, we might as well complete the picture: how the Guest tells us where | |
374 | * it wants them to go. This would be simple, except making traps fast | |
375 | * requires some tricks. | |
376 | * | |
377 | * We saw the Guest setting Interrupt Descriptor Table (IDT) entries with the | |
378 | * LHCALL_LOAD_IDT_ENTRY hypercall before: that comes here. */ | |
d7e28ffe RR |
379 | void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi) |
380 | { | |
bff672e6 RR |
381 | /* Guest never handles: NMI, doublefault, spurious interrupt or |
382 | * hypercall. We ignore when it tries to set them. */ | |
d7e28ffe RR |
383 | if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY) |
384 | return; | |
385 | ||
bff672e6 RR |
386 | /* Mark the IDT as changed: next time the Guest runs we'll know we have |
387 | * to copy this again. */ | |
d7e28ffe | 388 | lg->changed |= CHANGED_IDT; |
bff672e6 | 389 | |
56adbe9d | 390 | /* Check that the Guest doesn't try to step outside the bounds. */ |
625efab1 | 391 | if (num >= ARRAY_SIZE(lg->arch.idt)) |
56adbe9d RR |
392 | kill_guest(lg, "Setting idt entry %u", num); |
393 | else | |
625efab1 | 394 | set_trap(lg, &lg->arch.idt[num], num, lo, hi); |
d7e28ffe RR |
395 | } |
396 | ||
bff672e6 RR |
397 | /* The default entry for each interrupt points into the Switcher routines which |
398 | * simply return to the Host. The run_guest() loop will then call | |
399 | * deliver_trap() to bounce it back into the Guest. */ | |
d7e28ffe RR |
400 | static void default_idt_entry(struct desc_struct *idt, |
401 | int trap, | |
402 | const unsigned long handler) | |
403 | { | |
bff672e6 | 404 | /* A present interrupt gate. */ |
d7e28ffe RR |
405 | u32 flags = 0x8e00; |
406 | ||
bff672e6 RR |
407 | /* Set the privilege level on the entry for the hypercall: this allows |
408 | * the Guest to use the "int" instruction to trigger it. */ | |
d7e28ffe RR |
409 | if (trap == LGUEST_TRAP_ENTRY) |
410 | flags |= (GUEST_PL << 13); | |
411 | ||
bff672e6 | 412 | /* Now pack it into the IDT entry in its weird format. */ |
d7e28ffe RR |
413 | idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF); |
414 | idt->b = (handler&0xFFFF0000) | flags; | |
415 | } | |
416 | ||
bff672e6 | 417 | /* When the Guest first starts, we put default entries into the IDT. */ |
d7e28ffe RR |
418 | void setup_default_idt_entries(struct lguest_ro_state *state, |
419 | const unsigned long *def) | |
420 | { | |
421 | unsigned int i; | |
422 | ||
423 | for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++) | |
424 | default_idt_entry(&state->guest_idt[i], i, def[i]); | |
425 | } | |
426 | ||
bff672e6 RR |
427 | /*H:240 We don't use the IDT entries in the "struct lguest" directly, instead |
428 | * we copy them into the IDT which we've set up for Guests on this CPU, just | |
429 | * before we run the Guest. This routine does that copy. */ | |
d7e28ffe RR |
430 | void copy_traps(const struct lguest *lg, struct desc_struct *idt, |
431 | const unsigned long *def) | |
432 | { | |
433 | unsigned int i; | |
434 | ||
bff672e6 RR |
435 | /* We can simply copy the direct traps, otherwise we use the default |
436 | * ones in the Switcher: they will return to the Host. */ | |
625efab1 | 437 | for (i = 0; i < ARRAY_SIZE(lg->arch.idt); i++) { |
56adbe9d RR |
438 | /* If no Guest can ever override this trap, leave it alone. */ |
439 | if (!direct_trap(i)) | |
440 | continue; | |
441 | ||
442 | /* Only trap gates (type 15) can go direct to the Guest. | |
443 | * Interrupt gates (type 14) disable interrupts as they are | |
444 | * entered, which we never let the Guest do. Not present | |
445 | * entries (type 0x0) also can't go direct, of course. */ | |
625efab1 JS |
446 | if (idt_type(lg->arch.idt[i].a, lg->arch.idt[i].b) == 0xF) |
447 | idt[i] = lg->arch.idt[i]; | |
d7e28ffe | 448 | else |
56adbe9d | 449 | /* Reset it to the default. */ |
d7e28ffe RR |
450 | default_idt_entry(&idt[i], i, def[i]); |
451 | } | |
d7e28ffe RR |
452 | } |
453 | ||
454 | void guest_set_clockevent(struct lguest *lg, unsigned long delta) | |
455 | { | |
456 | ktime_t expires; | |
457 | ||
458 | if (unlikely(delta == 0)) { | |
459 | /* Clock event device is shutting down. */ | |
460 | hrtimer_cancel(&lg->hrt); | |
461 | return; | |
462 | } | |
463 | ||
464 | expires = ktime_add_ns(ktime_get_real(), delta); | |
465 | hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS); | |
466 | } | |
467 | ||
468 | static enum hrtimer_restart clockdev_fn(struct hrtimer *timer) | |
469 | { | |
470 | struct lguest *lg = container_of(timer, struct lguest, hrt); | |
471 | ||
472 | set_bit(0, lg->irqs_pending); | |
473 | if (lg->halted) | |
474 | wake_up_process(lg->tsk); | |
475 | return HRTIMER_NORESTART; | |
476 | } | |
477 | ||
478 | void init_clockdev(struct lguest *lg) | |
479 | { | |
480 | hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS); | |
481 | lg->hrt.function = clockdev_fn; | |
482 | } |