Rusty Russell | f938d2c | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1 | /*P:010 |
| 2 | * A hypervisor allows multiple Operating Systems to run on a single machine. |
| 3 | * To quote David Wheeler: "Any problem in computer science can be solved with |
| 4 | * another layer of indirection." |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 5 | * |
Rusty Russell | f938d2c | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 6 | * We keep things simple in two ways. First, we start with a normal Linux |
| 7 | * kernel and insert a module (lg.ko) which allows us to run other Linux |
| 8 | * kernels the same way we'd run processes. We call the first kernel the Host, |
| 9 | * and the others the Guests. The program which sets up and configures Guests |
| 10 | * (such as the example in Documentation/lguest/lguest.c) is called the |
| 11 | * Launcher. |
| 12 | * |
| 13 | * Secondly, we only run specially modified Guests, not normal kernels. When |
| 14 | * you set CONFIG_LGUEST to 'y' or 'm', this automatically sets |
| 15 | * CONFIG_LGUEST_GUEST=y, which compiles this file into the kernel so it knows |
| 16 | * how to be a Guest. This means that you can use the same kernel you boot |
| 17 | * normally (ie. as a Host) as a Guest. |
| 18 | * |
| 19 | * These Guests know that they cannot do privileged operations, such as disable |
| 20 | * interrupts, and that they have to ask the Host to do such things explicitly. |
| 21 | * This file consists of all the replacements for such low-level native |
| 22 | * hardware operations: these special Guest versions call the Host. |
| 23 | * |
| 24 | * So how does the kernel know it's a Guest? The Guest starts at a special |
| 25 | * entry point marked with a magic string, which sets up a few things then |
| 26 | * calls here. We replace the native functions in "struct paravirt_ops" |
| 27 | * with our Guest versions, then boot like normal. :*/ |
| 28 | |
| 29 | /* |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 30 | * Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation. |
| 31 | * |
| 32 | * This program is free software; you can redistribute it and/or modify |
| 33 | * it under the terms of the GNU General Public License as published by |
| 34 | * the Free Software Foundation; either version 2 of the License, or |
| 35 | * (at your option) any later version. |
| 36 | * |
| 37 | * This program is distributed in the hope that it will be useful, but |
| 38 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 39 | * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or |
| 40 | * NON INFRINGEMENT. See the GNU General Public License for more |
| 41 | * details. |
| 42 | * |
| 43 | * You should have received a copy of the GNU General Public License |
| 44 | * along with this program; if not, write to the Free Software |
| 45 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 46 | */ |
| 47 | #include <linux/kernel.h> |
| 48 | #include <linux/start_kernel.h> |
| 49 | #include <linux/string.h> |
| 50 | #include <linux/console.h> |
| 51 | #include <linux/screen_info.h> |
| 52 | #include <linux/irq.h> |
| 53 | #include <linux/interrupt.h> |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 54 | #include <linux/clocksource.h> |
| 55 | #include <linux/clockchips.h> |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 56 | #include <linux/lguest.h> |
| 57 | #include <linux/lguest_launcher.h> |
| 58 | #include <linux/lguest_bus.h> |
| 59 | #include <asm/paravirt.h> |
| 60 | #include <asm/param.h> |
| 61 | #include <asm/page.h> |
| 62 | #include <asm/pgtable.h> |
| 63 | #include <asm/desc.h> |
| 64 | #include <asm/setup.h> |
| 65 | #include <asm/e820.h> |
| 66 | #include <asm/mce.h> |
| 67 | #include <asm/io.h> |
| 68 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 69 | /*G:010 Welcome to the Guest! |
| 70 | * |
| 71 | * The Guest in our tale is a simple creature: identical to the Host but |
| 72 | * behaving in simplified but equivalent ways. In particular, the Guest is the |
| 73 | * same kernel as the Host (or at least, built from the same source code). :*/ |
| 74 | |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 75 | /* Declarations for definitions in lguest_guest.S */ |
| 76 | extern char lguest_noirq_start[], lguest_noirq_end[]; |
| 77 | extern const char lgstart_cli[], lgend_cli[]; |
| 78 | extern const char lgstart_sti[], lgend_sti[]; |
| 79 | extern const char lgstart_popf[], lgend_popf[]; |
| 80 | extern const char lgstart_pushf[], lgend_pushf[]; |
| 81 | extern const char lgstart_iret[], lgend_iret[]; |
| 82 | extern void lguest_iret(void); |
| 83 | |
| 84 | struct lguest_data lguest_data = { |
| 85 | .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF }, |
| 86 | .noirq_start = (u32)lguest_noirq_start, |
| 87 | .noirq_end = (u32)lguest_noirq_end, |
| 88 | .blocked_interrupts = { 1 }, /* Block timer interrupts */ |
| 89 | }; |
| 90 | struct lguest_device_desc *lguest_devices; |
Rusty Russell | 9d1ca6f | 2007-07-20 22:15:01 +1000 | [diff] [blame] | 91 | static cycle_t clock_base; |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 92 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 93 | /*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first |
| 94 | * real optimization trick! |
| 95 | * |
| 96 | * When lazy_mode is set, it means we're allowed to defer all hypercalls and do |
| 97 | * them as a batch when lazy_mode is eventually turned off. Because hypercalls |
| 98 | * are reasonably expensive, batching them up makes sense. For example, a |
| 99 | * large mmap might update dozens of page table entries: that code calls |
| 100 | * lguest_lazy_mode(PARAVIRT_LAZY_MMU), does the dozen updates, then calls |
| 101 | * lguest_lazy_mode(PARAVIRT_LAZY_NONE). |
| 102 | * |
| 103 | * So, when we're in lazy mode, we call async_hypercall() to store the call for |
| 104 | * future processing. When lazy mode is turned off we issue a hypercall to |
| 105 | * flush the stored calls. |
| 106 | * |
| 107 | * There's also a hack where "mode" is set to "PARAVIRT_LAZY_FLUSH" which |
| 108 | * indicates we're to flush any outstanding calls immediately. This is used |
| 109 | * when an interrupt handler does a kmap_atomic(): the page table changes must |
| 110 | * happen immediately even if we're in the middle of a batch. Usually we're |
| 111 | * not, though, so there's nothing to do. */ |
| 112 | static enum paravirt_lazy_mode lazy_mode; /* Note: not SMP-safe! */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 113 | static void lguest_lazy_mode(enum paravirt_lazy_mode mode) |
| 114 | { |
| 115 | if (mode == PARAVIRT_LAZY_FLUSH) { |
| 116 | if (unlikely(lazy_mode != PARAVIRT_LAZY_NONE)) |
| 117 | hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0); |
| 118 | } else { |
| 119 | lazy_mode = mode; |
| 120 | if (mode == PARAVIRT_LAZY_NONE) |
| 121 | hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0); |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | static void lazy_hcall(unsigned long call, |
| 126 | unsigned long arg1, |
| 127 | unsigned long arg2, |
| 128 | unsigned long arg3) |
| 129 | { |
| 130 | if (lazy_mode == PARAVIRT_LAZY_NONE) |
| 131 | hcall(call, arg1, arg2, arg3); |
| 132 | else |
| 133 | async_hcall(call, arg1, arg2, arg3); |
| 134 | } |
| 135 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 136 | /* async_hcall() is pretty simple: I'm quite proud of it really. We have a |
| 137 | * ring buffer of stored hypercalls which the Host will run though next time we |
| 138 | * do a normal hypercall. Each entry in the ring has 4 slots for the hypercall |
| 139 | * arguments, and a "hcall_status" word which is 0 if the call is ready to go, |
| 140 | * and 255 once the Host has finished with it. |
| 141 | * |
| 142 | * If we come around to a slot which hasn't been finished, then the table is |
| 143 | * full and we just make the hypercall directly. This has the nice side |
| 144 | * effect of causing the Host to run all the stored calls in the ring buffer |
| 145 | * which empties it for next time! */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 146 | void async_hcall(unsigned long call, |
| 147 | unsigned long arg1, unsigned long arg2, unsigned long arg3) |
| 148 | { |
| 149 | /* Note: This code assumes we're uniprocessor. */ |
| 150 | static unsigned int next_call; |
| 151 | unsigned long flags; |
| 152 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 153 | /* Disable interrupts if not already disabled: we don't want an |
| 154 | * interrupt handler making a hypercall while we're already doing |
| 155 | * one! */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 156 | local_irq_save(flags); |
| 157 | if (lguest_data.hcall_status[next_call] != 0xFF) { |
| 158 | /* Table full, so do normal hcall which will flush table. */ |
| 159 | hcall(call, arg1, arg2, arg3); |
| 160 | } else { |
| 161 | lguest_data.hcalls[next_call].eax = call; |
| 162 | lguest_data.hcalls[next_call].edx = arg1; |
| 163 | lguest_data.hcalls[next_call].ebx = arg2; |
| 164 | lguest_data.hcalls[next_call].ecx = arg3; |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 165 | /* Arguments must all be written before we mark it to go */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 166 | wmb(); |
| 167 | lguest_data.hcall_status[next_call] = 0; |
| 168 | if (++next_call == LHCALL_RING_SIZE) |
| 169 | next_call = 0; |
| 170 | } |
| 171 | local_irq_restore(flags); |
| 172 | } |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 173 | /*:*/ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 174 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 175 | /* Wrappers for the SEND_DMA and BIND_DMA hypercalls. This is mainly because |
| 176 | * Jeff Garzik complained that __pa() should never appear in drivers, and this |
| 177 | * helps remove most of them. But also, it wraps some ugliness. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 178 | void lguest_send_dma(unsigned long key, struct lguest_dma *dma) |
| 179 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 180 | /* The hcall might not write this if something goes wrong */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 181 | dma->used_len = 0; |
| 182 | hcall(LHCALL_SEND_DMA, key, __pa(dma), 0); |
| 183 | } |
| 184 | |
| 185 | int lguest_bind_dma(unsigned long key, struct lguest_dma *dmas, |
| 186 | unsigned int num, u8 irq) |
| 187 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 188 | /* This is the only hypercall which actually wants 5 arguments, and we |
| 189 | * only support 4. Fortunately the interrupt number is always less |
| 190 | * than 256, so we can pack it with the number of dmas in the final |
| 191 | * argument. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 192 | if (!hcall(LHCALL_BIND_DMA, key, __pa(dmas), (num << 8) | irq)) |
| 193 | return -ENOMEM; |
| 194 | return 0; |
| 195 | } |
| 196 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 197 | /* Unbinding is the same hypercall as binding, but with 0 num & irq. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 198 | void lguest_unbind_dma(unsigned long key, struct lguest_dma *dmas) |
| 199 | { |
| 200 | hcall(LHCALL_BIND_DMA, key, __pa(dmas), 0); |
| 201 | } |
| 202 | |
| 203 | /* For guests, device memory can be used as normal memory, so we cast away the |
| 204 | * __iomem to quieten sparse. */ |
| 205 | void *lguest_map(unsigned long phys_addr, unsigned long pages) |
| 206 | { |
| 207 | return (__force void *)ioremap(phys_addr, PAGE_SIZE*pages); |
| 208 | } |
| 209 | |
| 210 | void lguest_unmap(void *addr) |
| 211 | { |
| 212 | iounmap((__force void __iomem *)addr); |
| 213 | } |
| 214 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 215 | /*G:033 |
| 216 | * Here are our first native-instruction replacements: four functions for |
| 217 | * interrupt control. |
| 218 | * |
| 219 | * The simplest way of implementing these would be to have "turn interrupts |
| 220 | * off" and "turn interrupts on" hypercalls. Unfortunately, this is too slow: |
| 221 | * these are by far the most commonly called functions of those we override. |
| 222 | * |
| 223 | * So instead we keep an "irq_enabled" field inside our "struct lguest_data", |
| 224 | * which the Guest can update with a single instruction. The Host knows to |
| 225 | * check there when it wants to deliver an interrupt. |
| 226 | */ |
| 227 | |
| 228 | /* save_flags() is expected to return the processor state (ie. "eflags"). The |
| 229 | * eflags word contains all kind of stuff, but in practice Linux only cares |
| 230 | * about the interrupt flag. Our "save_flags()" just returns that. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 231 | static unsigned long save_fl(void) |
| 232 | { |
| 233 | return lguest_data.irq_enabled; |
| 234 | } |
| 235 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 236 | /* "restore_flags" just sets the flags back to the value given. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 237 | static void restore_fl(unsigned long flags) |
| 238 | { |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 239 | lguest_data.irq_enabled = flags; |
| 240 | } |
| 241 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 242 | /* Interrupts go off... */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 243 | static void irq_disable(void) |
| 244 | { |
| 245 | lguest_data.irq_enabled = 0; |
| 246 | } |
| 247 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 248 | /* Interrupts go on... */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 249 | static void irq_enable(void) |
| 250 | { |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 251 | lguest_data.irq_enabled = X86_EFLAGS_IF; |
| 252 | } |
Rusty Russell | f56a384 | 2007-07-26 10:41:05 -0700 | [diff] [blame] | 253 | /*:*/ |
| 254 | /*M:003 Note that we don't check for outstanding interrupts when we re-enable |
| 255 | * them (or when we unmask an interrupt). This seems to work for the moment, |
| 256 | * since interrupts are rare and we'll just get the interrupt on the next timer |
| 257 | * tick, but when we turn on CONFIG_NO_HZ, we should revisit this. One way |
| 258 | * would be to put the "irq_enabled" field in a page by itself, and have the |
| 259 | * Host write-protect it when an interrupt comes in when irqs are disabled. |
| 260 | * There will then be a page fault as soon as interrupts are re-enabled. :*/ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 261 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 262 | /*G:034 |
| 263 | * The Interrupt Descriptor Table (IDT). |
| 264 | * |
| 265 | * The IDT tells the processor what to do when an interrupt comes in. Each |
| 266 | * entry in the table is a 64-bit descriptor: this holds the privilege level, |
| 267 | * address of the handler, and... well, who cares? The Guest just asks the |
| 268 | * Host to make the change anyway, because the Host controls the real IDT. |
| 269 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 270 | static void lguest_write_idt_entry(struct desc_struct *dt, |
| 271 | int entrynum, u32 low, u32 high) |
| 272 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 273 | /* Keep the local copy up to date. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 274 | write_dt_entry(dt, entrynum, low, high); |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 275 | /* Tell Host about this new entry. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 276 | hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high); |
| 277 | } |
| 278 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 279 | /* Changing to a different IDT is very rare: we keep the IDT up-to-date every |
| 280 | * time it is written, so we can simply loop through all entries and tell the |
| 281 | * Host about them. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 282 | static void lguest_load_idt(const struct Xgt_desc_struct *desc) |
| 283 | { |
| 284 | unsigned int i; |
| 285 | struct desc_struct *idt = (void *)desc->address; |
| 286 | |
| 287 | for (i = 0; i < (desc->size+1)/8; i++) |
| 288 | hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b); |
| 289 | } |
| 290 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 291 | /* |
| 292 | * The Global Descriptor Table. |
| 293 | * |
| 294 | * The Intel architecture defines another table, called the Global Descriptor |
| 295 | * Table (GDT). You tell the CPU where it is (and its size) using the "lgdt" |
| 296 | * instruction, and then several other instructions refer to entries in the |
| 297 | * table. There are three entries which the Switcher needs, so the Host simply |
| 298 | * controls the entire thing and the Guest asks it to make changes using the |
| 299 | * LOAD_GDT hypercall. |
| 300 | * |
| 301 | * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY |
| 302 | * hypercall and use that repeatedly to load a new IDT. I don't think it |
| 303 | * really matters, but wouldn't it be nice if they were the same? |
| 304 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 305 | static void lguest_load_gdt(const struct Xgt_desc_struct *desc) |
| 306 | { |
| 307 | BUG_ON((desc->size+1)/8 != GDT_ENTRIES); |
| 308 | hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0); |
| 309 | } |
| 310 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 311 | /* For a single GDT entry which changes, we do the lazy thing: alter our GDT, |
| 312 | * then tell the Host to reload the entire thing. This operation is so rare |
| 313 | * that this naive implementation is reasonable. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 314 | static void lguest_write_gdt_entry(struct desc_struct *dt, |
| 315 | int entrynum, u32 low, u32 high) |
| 316 | { |
| 317 | write_dt_entry(dt, entrynum, low, high); |
| 318 | hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0); |
| 319 | } |
| 320 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 321 | /* OK, I lied. There are three "thread local storage" GDT entries which change |
| 322 | * on every context switch (these three entries are how glibc implements |
| 323 | * __thread variables). So we have a hypercall specifically for this case. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 324 | static void lguest_load_tls(struct thread_struct *t, unsigned int cpu) |
| 325 | { |
Rusty Russell | 0d027c0 | 2007-08-09 20:57:13 +1000 | [diff] [blame] | 326 | /* There's one problem which normal hardware doesn't have: the Host |
| 327 | * can't handle us removing entries we're currently using. So we clear |
| 328 | * the GS register here: if it's needed it'll be reloaded anyway. */ |
| 329 | loadsegment(gs, 0); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 330 | lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0); |
| 331 | } |
| 332 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 333 | /*G:038 That's enough excitement for now, back to ploughing through each of |
| 334 | * the paravirt_ops (we're about 1/3 of the way through). |
| 335 | * |
| 336 | * This is the Local Descriptor Table, another weird Intel thingy. Linux only |
| 337 | * uses this for some strange applications like Wine. We don't do anything |
| 338 | * here, so they'll get an informative and friendly Segmentation Fault. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 339 | static void lguest_set_ldt(const void *addr, unsigned entries) |
| 340 | { |
| 341 | } |
| 342 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 343 | /* This loads a GDT entry into the "Task Register": that entry points to a |
| 344 | * structure called the Task State Segment. Some comments scattered though the |
| 345 | * kernel code indicate that this used for task switching in ages past, along |
| 346 | * with blood sacrifice and astrology. |
| 347 | * |
| 348 | * Now there's nothing interesting in here that we don't get told elsewhere. |
| 349 | * But the native version uses the "ltr" instruction, which makes the Host |
| 350 | * complain to the Guest about a Segmentation Fault and it'll oops. So we |
| 351 | * override the native version with a do-nothing version. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 352 | static void lguest_load_tr_desc(void) |
| 353 | { |
| 354 | } |
| 355 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 356 | /* The "cpuid" instruction is a way of querying both the CPU identity |
| 357 | * (manufacturer, model, etc) and its features. It was introduced before the |
| 358 | * Pentium in 1993 and keeps getting extended by both Intel and AMD. As you |
| 359 | * might imagine, after a decade and a half this treatment, it is now a giant |
| 360 | * ball of hair. Its entry in the current Intel manual runs to 28 pages. |
| 361 | * |
| 362 | * This instruction even it has its own Wikipedia entry. The Wikipedia entry |
| 363 | * has been translated into 4 languages. I am not making this up! |
| 364 | * |
| 365 | * We could get funky here and identify ourselves as "GenuineLguest", but |
| 366 | * instead we just use the real "cpuid" instruction. Then I pretty much turned |
| 367 | * off feature bits until the Guest booted. (Don't say that: you'll damage |
| 368 | * lguest sales!) Shut up, inner voice! (Hey, just pointing out that this is |
| 369 | * hardly future proof.) Noone's listening! They don't like you anyway, |
| 370 | * parenthetic weirdo! |
| 371 | * |
| 372 | * Replacing the cpuid so we can turn features off is great for the kernel, but |
| 373 | * anyone (including userspace) can just use the raw "cpuid" instruction and |
| 374 | * the Host won't even notice since it isn't privileged. So we try not to get |
| 375 | * too worked up about it. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 376 | static void lguest_cpuid(unsigned int *eax, unsigned int *ebx, |
| 377 | unsigned int *ecx, unsigned int *edx) |
| 378 | { |
| 379 | int function = *eax; |
| 380 | |
| 381 | native_cpuid(eax, ebx, ecx, edx); |
| 382 | switch (function) { |
| 383 | case 1: /* Basic feature request. */ |
| 384 | /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */ |
| 385 | *ecx &= 0x00002201; |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 386 | /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 387 | *edx &= 0x07808101; |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 388 | /* The Host can do a nice optimization if it knows that the |
| 389 | * kernel mappings (addresses above 0xC0000000 or whatever |
| 390 | * PAGE_OFFSET is set to) haven't changed. But Linux calls |
| 391 | * flush_tlb_user() for both user and kernel mappings unless |
| 392 | * the Page Global Enable (PGE) feature bit is set. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 393 | *edx |= 0x00002000; |
| 394 | break; |
| 395 | case 0x80000000: |
| 396 | /* Futureproof this a little: if they ask how much extended |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 397 | * processor information there is, limit it to known fields. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 398 | if (*eax > 0x80000008) |
| 399 | *eax = 0x80000008; |
| 400 | break; |
| 401 | } |
| 402 | } |
| 403 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 404 | /* Intel has four control registers, imaginatively named cr0, cr2, cr3 and cr4. |
| 405 | * I assume there's a cr1, but it hasn't bothered us yet, so we'll not bother |
| 406 | * it. The Host needs to know when the Guest wants to change them, so we have |
| 407 | * a whole series of functions like read_cr0() and write_cr0(). |
| 408 | * |
| 409 | * We start with CR0. CR0 allows you to turn on and off all kinds of basic |
| 410 | * features, but Linux only really cares about one: the horrifically-named Task |
| 411 | * Switched (TS) bit at bit 3 (ie. 8) |
| 412 | * |
| 413 | * What does the TS bit do? Well, it causes the CPU to trap (interrupt 7) if |
| 414 | * the floating point unit is used. Which allows us to restore FPU state |
| 415 | * lazily after a task switch, and Linux uses that gratefully, but wouldn't a |
| 416 | * name like "FPUTRAP bit" be a little less cryptic? |
| 417 | * |
| 418 | * We store cr0 (and cr3) locally, because the Host never changes it. The |
| 419 | * Guest sometimes wants to read it and we'd prefer not to bother the Host |
| 420 | * unnecessarily. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 421 | static unsigned long current_cr0, current_cr3; |
| 422 | static void lguest_write_cr0(unsigned long val) |
| 423 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 424 | /* 8 == TS bit. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 425 | lazy_hcall(LHCALL_TS, val & 8, 0, 0); |
| 426 | current_cr0 = val; |
| 427 | } |
| 428 | |
| 429 | static unsigned long lguest_read_cr0(void) |
| 430 | { |
| 431 | return current_cr0; |
| 432 | } |
| 433 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 434 | /* Intel provided a special instruction to clear the TS bit for people too cool |
| 435 | * to use write_cr0() to do it. This "clts" instruction is faster, because all |
| 436 | * the vowels have been optimized out. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 437 | static void lguest_clts(void) |
| 438 | { |
| 439 | lazy_hcall(LHCALL_TS, 0, 0, 0); |
| 440 | current_cr0 &= ~8U; |
| 441 | } |
| 442 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 443 | /* CR2 is the virtual address of the last page fault, which the Guest only ever |
| 444 | * reads. The Host kindly writes this into our "struct lguest_data", so we |
| 445 | * just read it out of there. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 446 | static unsigned long lguest_read_cr2(void) |
| 447 | { |
| 448 | return lguest_data.cr2; |
| 449 | } |
| 450 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 451 | /* CR3 is the current toplevel pagetable page: the principle is the same as |
| 452 | * cr0. Keep a local copy, and tell the Host when it changes. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 453 | static void lguest_write_cr3(unsigned long cr3) |
| 454 | { |
| 455 | lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0); |
| 456 | current_cr3 = cr3; |
| 457 | } |
| 458 | |
| 459 | static unsigned long lguest_read_cr3(void) |
| 460 | { |
| 461 | return current_cr3; |
| 462 | } |
| 463 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 464 | /* CR4 is used to enable and disable PGE, but we don't care. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 465 | static unsigned long lguest_read_cr4(void) |
| 466 | { |
| 467 | return 0; |
| 468 | } |
| 469 | |
| 470 | static void lguest_write_cr4(unsigned long val) |
| 471 | { |
| 472 | } |
| 473 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 474 | /* |
| 475 | * Page Table Handling. |
| 476 | * |
| 477 | * Now would be a good time to take a rest and grab a coffee or similarly |
| 478 | * relaxing stimulant. The easy parts are behind us, and the trek gradually |
| 479 | * winds uphill from here. |
| 480 | * |
| 481 | * Quick refresher: memory is divided into "pages" of 4096 bytes each. The CPU |
| 482 | * maps virtual addresses to physical addresses using "page tables". We could |
| 483 | * use one huge index of 1 million entries: each address is 4 bytes, so that's |
| 484 | * 1024 pages just to hold the page tables. But since most virtual addresses |
| 485 | * are unused, we use a two level index which saves space. The CR3 register |
| 486 | * contains the physical address of the top level "page directory" page, which |
| 487 | * contains physical addresses of up to 1024 second-level pages. Each of these |
| 488 | * second level pages contains up to 1024 physical addresses of actual pages, |
| 489 | * or Page Table Entries (PTEs). |
| 490 | * |
| 491 | * Here's a diagram, where arrows indicate physical addresses: |
| 492 | * |
| 493 | * CR3 ---> +---------+ |
| 494 | * | --------->+---------+ |
| 495 | * | | | PADDR1 | |
| 496 | * Top-level | | PADDR2 | |
| 497 | * (PMD) page | | | |
| 498 | * | | Lower-level | |
| 499 | * | | (PTE) page | |
| 500 | * | | | | |
| 501 | * .... .... |
| 502 | * |
| 503 | * So to convert a virtual address to a physical address, we look up the top |
| 504 | * level, which points us to the second level, which gives us the physical |
| 505 | * address of that page. If the top level entry was not present, or the second |
| 506 | * level entry was not present, then the virtual address is invalid (we |
| 507 | * say "the page was not mapped"). |
| 508 | * |
| 509 | * Put another way, a 32-bit virtual address is divided up like so: |
| 510 | * |
| 511 | * 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 |
| 512 | * |<---- 10 bits ---->|<---- 10 bits ---->|<------ 12 bits ------>| |
| 513 | * Index into top Index into second Offset within page |
| 514 | * page directory page pagetable page |
| 515 | * |
| 516 | * The kernel spends a lot of time changing both the top-level page directory |
| 517 | * and lower-level pagetable pages. The Guest doesn't know physical addresses, |
| 518 | * so while it maintains these page tables exactly like normal, it also needs |
| 519 | * to keep the Host informed whenever it makes a change: the Host will create |
| 520 | * the real page tables based on the Guests'. |
| 521 | */ |
| 522 | |
| 523 | /* The Guest calls this to set a second-level entry (pte), ie. to map a page |
| 524 | * into a process' address space. We set the entry then tell the Host the |
| 525 | * toplevel and address this corresponds to. The Guest uses one pagetable per |
| 526 | * process, so we need to tell the Host which one we're changing (mm->pgd). */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 527 | static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr, |
| 528 | pte_t *ptep, pte_t pteval) |
| 529 | { |
| 530 | *ptep = pteval; |
| 531 | lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low); |
| 532 | } |
| 533 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 534 | /* The Guest calls this to set a top-level entry. Again, we set the entry then |
| 535 | * tell the Host which top-level page we changed, and the index of the entry we |
| 536 | * changed. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 537 | static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval) |
| 538 | { |
| 539 | *pmdp = pmdval; |
| 540 | lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK, |
| 541 | (__pa(pmdp)&(PAGE_SIZE-1))/4, 0); |
| 542 | } |
| 543 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 544 | /* There are a couple of legacy places where the kernel sets a PTE, but we |
| 545 | * don't know the top level any more. This is useless for us, since we don't |
| 546 | * know which pagetable is changing or what address, so we just tell the Host |
| 547 | * to forget all of them. Fortunately, this is very rare. |
| 548 | * |
| 549 | * ... except in early boot when the kernel sets up the initial pagetables, |
| 550 | * which makes booting astonishingly slow. So we don't even tell the Host |
| 551 | * anything changed until we've done the first page table switch. |
| 552 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 553 | static void lguest_set_pte(pte_t *ptep, pte_t pteval) |
| 554 | { |
| 555 | *ptep = pteval; |
| 556 | /* Don't bother with hypercall before initial setup. */ |
| 557 | if (current_cr3) |
| 558 | lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0); |
| 559 | } |
| 560 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 561 | /* Unfortunately for Lguest, the paravirt_ops for page tables were based on |
| 562 | * native page table operations. On native hardware you can set a new page |
| 563 | * table entry whenever you want, but if you want to remove one you have to do |
| 564 | * a TLB flush (a TLB is a little cache of page table entries kept by the CPU). |
| 565 | * |
| 566 | * So the lguest_set_pte_at() and lguest_set_pmd() functions above are only |
| 567 | * called when a valid entry is written, not when it's removed (ie. marked not |
| 568 | * present). Instead, this is where we come when the Guest wants to remove a |
| 569 | * page table entry: we tell the Host to set that entry to 0 (ie. the present |
| 570 | * bit is zero). */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 571 | static void lguest_flush_tlb_single(unsigned long addr) |
| 572 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 573 | /* Simply set it to zero: if it was not, it will fault back in. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 574 | lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0); |
| 575 | } |
| 576 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 577 | /* This is what happens after the Guest has removed a large number of entries. |
| 578 | * This tells the Host that any of the page table entries for userspace might |
| 579 | * have changed, ie. virtual addresses below PAGE_OFFSET. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 580 | static void lguest_flush_tlb_user(void) |
| 581 | { |
| 582 | lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0); |
| 583 | } |
| 584 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 585 | /* This is called when the kernel page tables have changed. That's not very |
| 586 | * common (unless the Guest is using highmem, which makes the Guest extremely |
| 587 | * slow), so it's worth separating this from the user flushing above. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 588 | static void lguest_flush_tlb_kernel(void) |
| 589 | { |
| 590 | lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0); |
| 591 | } |
| 592 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 593 | /* |
| 594 | * The Unadvanced Programmable Interrupt Controller. |
| 595 | * |
| 596 | * This is an attempt to implement the simplest possible interrupt controller. |
| 597 | * I spent some time looking though routines like set_irq_chip_and_handler, |
| 598 | * set_irq_chip_and_handler_name, set_irq_chip_data and set_phasers_to_stun and |
| 599 | * I *think* this is as simple as it gets. |
| 600 | * |
| 601 | * We can tell the Host what interrupts we want blocked ready for using the |
| 602 | * lguest_data.interrupts bitmap, so disabling (aka "masking") them is as |
| 603 | * simple as setting a bit. We don't actually "ack" interrupts as such, we |
| 604 | * just mask and unmask them. I wonder if we should be cleverer? |
| 605 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 606 | static void disable_lguest_irq(unsigned int irq) |
| 607 | { |
| 608 | set_bit(irq, lguest_data.blocked_interrupts); |
| 609 | } |
| 610 | |
| 611 | static void enable_lguest_irq(unsigned int irq) |
| 612 | { |
| 613 | clear_bit(irq, lguest_data.blocked_interrupts); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 614 | } |
| 615 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 616 | /* This structure describes the lguest IRQ controller. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 617 | static struct irq_chip lguest_irq_controller = { |
| 618 | .name = "lguest", |
| 619 | .mask = disable_lguest_irq, |
| 620 | .mask_ack = disable_lguest_irq, |
| 621 | .unmask = enable_lguest_irq, |
| 622 | }; |
| 623 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 624 | /* This sets up the Interrupt Descriptor Table (IDT) entry for each hardware |
| 625 | * interrupt (except 128, which is used for system calls), and then tells the |
| 626 | * Linux infrastructure that each interrupt is controlled by our level-based |
| 627 | * lguest interrupt controller. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 628 | static void __init lguest_init_IRQ(void) |
| 629 | { |
| 630 | unsigned int i; |
| 631 | |
| 632 | for (i = 0; i < LGUEST_IRQS; i++) { |
| 633 | int vector = FIRST_EXTERNAL_VECTOR + i; |
| 634 | if (vector != SYSCALL_VECTOR) { |
| 635 | set_intr_gate(vector, interrupt[i]); |
| 636 | set_irq_chip_and_handler(i, &lguest_irq_controller, |
| 637 | handle_level_irq); |
| 638 | } |
| 639 | } |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 640 | /* This call is required to set up for 4k stacks, where we have |
| 641 | * separate stacks for hard and soft interrupts. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 642 | irq_ctx_init(smp_processor_id()); |
| 643 | } |
| 644 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 645 | /* |
| 646 | * Time. |
| 647 | * |
| 648 | * It would be far better for everyone if the Guest had its own clock, but |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 649 | * until then the Host gives us the time on every interrupt. |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 650 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 651 | static unsigned long lguest_get_wallclock(void) |
| 652 | { |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 653 | return lguest_data.time.tv_sec; |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 654 | } |
| 655 | |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 656 | static cycle_t lguest_clock_read(void) |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 657 | { |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 658 | unsigned long sec, nsec; |
| 659 | |
| 660 | /* If the Host tells the TSC speed, we can trust that. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 661 | if (lguest_data.tsc_khz) |
| 662 | return native_read_tsc(); |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 663 | |
| 664 | /* If we can't use the TSC, we read the time value written by the Host. |
| 665 | * Since it's in two parts (seconds and nanoseconds), we risk reading |
| 666 | * it just as it's changing from 99 & 0.999999999 to 100 and 0, and |
| 667 | * getting 99 and 0. As Linux tends to come apart under the stress of |
| 668 | * time travel, we must be careful: */ |
| 669 | do { |
| 670 | /* First we read the seconds part. */ |
| 671 | sec = lguest_data.time.tv_sec; |
| 672 | /* This read memory barrier tells the compiler and the CPU that |
| 673 | * this can't be reordered: we have to complete the above |
| 674 | * before going on. */ |
| 675 | rmb(); |
| 676 | /* Now we read the nanoseconds part. */ |
| 677 | nsec = lguest_data.time.tv_nsec; |
| 678 | /* Make sure we've done that. */ |
| 679 | rmb(); |
| 680 | /* Now if the seconds part has changed, try again. */ |
| 681 | } while (unlikely(lguest_data.time.tv_sec != sec)); |
| 682 | |
| 683 | /* Our non-TSC clock is in real nanoseconds. */ |
| 684 | return sec*1000000000ULL + nsec; |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 685 | } |
| 686 | |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 687 | /* This is what we tell the kernel is our clocksource. */ |
| 688 | static struct clocksource lguest_clock = { |
| 689 | .name = "lguest", |
| 690 | .rating = 400, |
| 691 | .read = lguest_clock_read, |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 692 | .mask = CLOCKSOURCE_MASK(64), |
Rusty Russell | 3725009 | 2007-08-09 20:52:35 +1000 | [diff] [blame] | 693 | .mult = 1 << 22, |
| 694 | .shift = 22, |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 695 | }; |
| 696 | |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 697 | /* The "scheduler clock" is just our real clock, adjusted to start at zero */ |
Rusty Russell | 9d1ca6f | 2007-07-20 22:15:01 +1000 | [diff] [blame] | 698 | static unsigned long long lguest_sched_clock(void) |
| 699 | { |
| 700 | return cyc2ns(&lguest_clock, lguest_clock_read() - clock_base); |
| 701 | } |
| 702 | |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 703 | /* We also need a "struct clock_event_device": Linux asks us to set it to go |
| 704 | * off some time in the future. Actually, James Morris figured all this out, I |
| 705 | * just applied the patch. */ |
| 706 | static int lguest_clockevent_set_next_event(unsigned long delta, |
| 707 | struct clock_event_device *evt) |
| 708 | { |
| 709 | if (delta < LG_CLOCK_MIN_DELTA) { |
| 710 | if (printk_ratelimit()) |
| 711 | printk(KERN_DEBUG "%s: small delta %lu ns\n", |
| 712 | __FUNCTION__, delta); |
| 713 | return -ETIME; |
| 714 | } |
| 715 | hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0); |
| 716 | return 0; |
| 717 | } |
| 718 | |
| 719 | static void lguest_clockevent_set_mode(enum clock_event_mode mode, |
| 720 | struct clock_event_device *evt) |
| 721 | { |
| 722 | switch (mode) { |
| 723 | case CLOCK_EVT_MODE_UNUSED: |
| 724 | case CLOCK_EVT_MODE_SHUTDOWN: |
| 725 | /* A 0 argument shuts the clock down. */ |
| 726 | hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0); |
| 727 | break; |
| 728 | case CLOCK_EVT_MODE_ONESHOT: |
| 729 | /* This is what we expect. */ |
| 730 | break; |
| 731 | case CLOCK_EVT_MODE_PERIODIC: |
| 732 | BUG(); |
Thomas Gleixner | 18de5bc | 2007-07-21 04:37:34 -0700 | [diff] [blame] | 733 | case CLOCK_EVT_MODE_RESUME: |
| 734 | break; |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 735 | } |
| 736 | } |
| 737 | |
| 738 | /* This describes our primitive timer chip. */ |
| 739 | static struct clock_event_device lguest_clockevent = { |
| 740 | .name = "lguest", |
| 741 | .features = CLOCK_EVT_FEAT_ONESHOT, |
| 742 | .set_next_event = lguest_clockevent_set_next_event, |
| 743 | .set_mode = lguest_clockevent_set_mode, |
| 744 | .rating = INT_MAX, |
| 745 | .mult = 1, |
| 746 | .shift = 0, |
| 747 | .min_delta_ns = LG_CLOCK_MIN_DELTA, |
| 748 | .max_delta_ns = LG_CLOCK_MAX_DELTA, |
| 749 | }; |
| 750 | |
| 751 | /* This is the Guest timer interrupt handler (hardware interrupt 0). We just |
| 752 | * call the clockevent infrastructure and it does whatever needs doing. */ |
| 753 | static void lguest_time_irq(unsigned int irq, struct irq_desc *desc) |
| 754 | { |
| 755 | unsigned long flags; |
| 756 | |
| 757 | /* Don't interrupt us while this is running. */ |
| 758 | local_irq_save(flags); |
| 759 | lguest_clockevent.event_handler(&lguest_clockevent); |
| 760 | local_irq_restore(flags); |
| 761 | } |
| 762 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 763 | /* At some point in the boot process, we get asked to set up our timing |
| 764 | * infrastructure. The kernel doesn't expect timer interrupts before this, but |
| 765 | * we cleverly initialized the "blocked_interrupts" field of "struct |
| 766 | * lguest_data" so that timer interrupts were blocked until now. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 767 | static void lguest_time_init(void) |
| 768 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 769 | /* Set up the timer interrupt (0) to go to our simple timer routine */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 770 | set_irq_handler(0, lguest_time_irq); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 771 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 772 | /* Our clock structure look like arch/i386/kernel/tsc.c if we can use |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 773 | * the TSC, otherwise it's a dumb nanosecond-resolution clock. Either |
| 774 | * way, the "rating" is initialized so high that it's always chosen |
| 775 | * over any other clocksource. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 776 | if (lguest_data.tsc_khz) { |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 777 | lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz, |
| 778 | lguest_clock.shift); |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 779 | lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS; |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 780 | } |
Rusty Russell | 9d1ca6f | 2007-07-20 22:15:01 +1000 | [diff] [blame] | 781 | clock_base = lguest_clock_read(); |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 782 | clocksource_register(&lguest_clock); |
| 783 | |
Rusty Russell | 6c8dca5 | 2007-07-27 13:42:52 +1000 | [diff] [blame] | 784 | /* Now we've set up our clock, we can use it as the scheduler clock */ |
| 785 | paravirt_ops.sched_clock = lguest_sched_clock; |
| 786 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 787 | /* We can't set cpumask in the initializer: damn C limitations! Set it |
| 788 | * here and register our timer device. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 789 | lguest_clockevent.cpumask = cpumask_of_cpu(0); |
| 790 | clockevents_register_device(&lguest_clockevent); |
| 791 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 792 | /* Finally, we unblock the timer interrupt. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 793 | enable_lguest_irq(0); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 794 | } |
| 795 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 796 | /* |
| 797 | * Miscellaneous bits and pieces. |
| 798 | * |
| 799 | * Here is an oddball collection of functions which the Guest needs for things |
| 800 | * to work. They're pretty simple. |
| 801 | */ |
| 802 | |
| 803 | /* The Guest needs to tell the host what stack it expects traps to use. For |
| 804 | * native hardware, this is part of the Task State Segment mentioned above in |
| 805 | * lguest_load_tr_desc(), but to help hypervisors there's this special call. |
| 806 | * |
| 807 | * We tell the Host the segment we want to use (__KERNEL_DS is the kernel data |
| 808 | * segment), the privilege level (we're privilege level 1, the Host is 0 and |
| 809 | * will not tolerate us trying to use that), the stack pointer, and the number |
| 810 | * of pages in the stack. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 811 | static void lguest_load_esp0(struct tss_struct *tss, |
| 812 | struct thread_struct *thread) |
| 813 | { |
| 814 | lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->esp0, |
| 815 | THREAD_SIZE/PAGE_SIZE); |
| 816 | } |
| 817 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 818 | /* Let's just say, I wouldn't do debugging under a Guest. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 819 | static void lguest_set_debugreg(int regno, unsigned long value) |
| 820 | { |
| 821 | /* FIXME: Implement */ |
| 822 | } |
| 823 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 824 | /* There are times when the kernel wants to make sure that no memory writes are |
| 825 | * caught in the cache (that they've all reached real hardware devices). This |
| 826 | * doesn't matter for the Guest which has virtual hardware. |
| 827 | * |
| 828 | * On the Pentium 4 and above, cpuid() indicates that the Cache Line Flush |
| 829 | * (clflush) instruction is available and the kernel uses that. Otherwise, it |
| 830 | * uses the older "Write Back and Invalidate Cache" (wbinvd) instruction. |
| 831 | * Unlike clflush, wbinvd can only be run at privilege level 0. So we can |
| 832 | * ignore clflush, but replace wbinvd. |
| 833 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 834 | static void lguest_wbinvd(void) |
| 835 | { |
| 836 | } |
| 837 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 838 | /* If the Guest expects to have an Advanced Programmable Interrupt Controller, |
| 839 | * we play dumb by ignoring writes and returning 0 for reads. So it's no |
| 840 | * longer Programmable nor Controlling anything, and I don't think 8 lines of |
| 841 | * code qualifies for Advanced. It will also never interrupt anything. It |
| 842 | * does, however, allow us to get through the Linux boot code. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 843 | #ifdef CONFIG_X86_LOCAL_APIC |
| 844 | static void lguest_apic_write(unsigned long reg, unsigned long v) |
| 845 | { |
| 846 | } |
| 847 | |
| 848 | static unsigned long lguest_apic_read(unsigned long reg) |
| 849 | { |
| 850 | return 0; |
| 851 | } |
| 852 | #endif |
| 853 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 854 | /* STOP! Until an interrupt comes in. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 855 | static void lguest_safe_halt(void) |
| 856 | { |
| 857 | hcall(LHCALL_HALT, 0, 0, 0); |
| 858 | } |
| 859 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 860 | /* Perhaps CRASH isn't the best name for this hypercall, but we use it to get a |
| 861 | * message out when we're crashing as well as elegant termination like powering |
| 862 | * off. |
| 863 | * |
| 864 | * Note that the Host always prefers that the Guest speak in physical addresses |
| 865 | * rather than virtual addresses, so we use __pa() here. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 866 | static void lguest_power_off(void) |
| 867 | { |
| 868 | hcall(LHCALL_CRASH, __pa("Power down"), 0, 0); |
| 869 | } |
| 870 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 871 | /* |
| 872 | * Panicing. |
| 873 | * |
| 874 | * Don't. But if you did, this is what happens. |
| 875 | */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 876 | static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p) |
| 877 | { |
| 878 | hcall(LHCALL_CRASH, __pa(p), 0, 0); |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 879 | /* The hcall won't return, but to keep gcc happy, we're "done". */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 880 | return NOTIFY_DONE; |
| 881 | } |
| 882 | |
| 883 | static struct notifier_block paniced = { |
| 884 | .notifier_call = lguest_panic |
| 885 | }; |
| 886 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 887 | /* Setting up memory is fairly easy. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 888 | static __init char *lguest_memory_setup(void) |
| 889 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 890 | /* We do this here and not earlier because lockcheck barfs if we do it |
| 891 | * before start_kernel() */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 892 | atomic_notifier_chain_register(&panic_notifier_list, &paniced); |
| 893 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 894 | /* The Linux bootloader header contains an "e820" memory map: the |
| 895 | * Launcher populated the first entry with our memory limit. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 896 | add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type); |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 897 | |
| 898 | /* This string is for the boot messages. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 899 | return "LGUEST"; |
| 900 | } |
| 901 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 902 | /*G:050 |
| 903 | * Patching (Powerfully Placating Performance Pedants) |
| 904 | * |
| 905 | * We have already seen that "struct paravirt_ops" lets us replace simple |
| 906 | * native instructions with calls to the appropriate back end all throughout |
| 907 | * the kernel. This allows the same kernel to run as a Guest and as a native |
| 908 | * kernel, but it's slow because of all the indirect branches. |
| 909 | * |
| 910 | * Remember that David Wheeler quote about "Any problem in computer science can |
| 911 | * be solved with another layer of indirection"? The rest of that quote is |
| 912 | * "... But that usually will create another problem." This is the first of |
| 913 | * those problems. |
| 914 | * |
| 915 | * Our current solution is to allow the paravirt back end to optionally patch |
| 916 | * over the indirect calls to replace them with something more efficient. We |
| 917 | * patch the four most commonly called functions: disable interrupts, enable |
| 918 | * interrupts, restore interrupts and save interrupts. We usually have 10 |
| 919 | * bytes to patch into: the Guest versions of these operations are small enough |
| 920 | * that we can fit comfortably. |
| 921 | * |
| 922 | * First we need assembly templates of each of the patchable Guest operations, |
| 923 | * and these are in lguest_asm.S. */ |
| 924 | |
| 925 | /*G:060 We construct a table from the assembler templates: */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 926 | static const struct lguest_insns |
| 927 | { |
| 928 | const char *start, *end; |
| 929 | } lguest_insns[] = { |
| 930 | [PARAVIRT_PATCH(irq_disable)] = { lgstart_cli, lgend_cli }, |
| 931 | [PARAVIRT_PATCH(irq_enable)] = { lgstart_sti, lgend_sti }, |
| 932 | [PARAVIRT_PATCH(restore_fl)] = { lgstart_popf, lgend_popf }, |
| 933 | [PARAVIRT_PATCH(save_fl)] = { lgstart_pushf, lgend_pushf }, |
| 934 | }; |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 935 | |
| 936 | /* Now our patch routine is fairly simple (based on the native one in |
| 937 | * paravirt.c). If we have a replacement, we copy it in and return how much of |
| 938 | * the available space we used. */ |
Andi Kleen | ab144f5 | 2007-08-10 22:31:03 +0200 | [diff] [blame] | 939 | static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf, |
| 940 | unsigned long addr, unsigned len) |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 941 | { |
| 942 | unsigned int insn_len; |
| 943 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 944 | /* Don't do anything special if we don't have a replacement */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 945 | if (type >= ARRAY_SIZE(lguest_insns) || !lguest_insns[type].start) |
Andi Kleen | ab144f5 | 2007-08-10 22:31:03 +0200 | [diff] [blame] | 946 | return paravirt_patch_default(type, clobber, ibuf, addr, len); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 947 | |
| 948 | insn_len = lguest_insns[type].end - lguest_insns[type].start; |
| 949 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 950 | /* Similarly if we can't fit replacement (shouldn't happen, but let's |
| 951 | * be thorough). */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 952 | if (len < insn_len) |
Andi Kleen | ab144f5 | 2007-08-10 22:31:03 +0200 | [diff] [blame] | 953 | return paravirt_patch_default(type, clobber, ibuf, addr, len); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 954 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 955 | /* Copy in our instructions. */ |
Andi Kleen | ab144f5 | 2007-08-10 22:31:03 +0200 | [diff] [blame] | 956 | memcpy(ibuf, lguest_insns[type].start, insn_len); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 957 | return insn_len; |
| 958 | } |
| 959 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 960 | /*G:030 Once we get to lguest_init(), we know we're a Guest. The paravirt_ops |
| 961 | * structure in the kernel provides a single point for (almost) every routine |
| 962 | * we have to override to avoid privileged instructions. */ |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 963 | __init void lguest_init(void *boot) |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 964 | { |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 965 | /* Copy boot parameters first: the Launcher put the physical location |
| 966 | * in %esi, and head.S converted that to a virtual address and handed |
Rusty Russell | c413fec | 2007-09-11 17:06:37 +1000 | [diff] [blame] | 967 | * it to us. We use "__memcpy" because "memcpy" sometimes tries to do |
| 968 | * tricky things to go faster, and we're not ready for that. */ |
| 969 | __memcpy(&boot_params, boot, PARAM_SIZE); |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 970 | /* The boot parameters also tell us where the command-line is: save |
| 971 | * that, too. */ |
Rusty Russell | c413fec | 2007-09-11 17:06:37 +1000 | [diff] [blame] | 972 | __memcpy(boot_command_line, __va(boot_params.hdr.cmd_line_ptr), |
Rusty Russell | d7e28ff | 2007-07-19 01:49:23 -0700 | [diff] [blame] | 973 | COMMAND_LINE_SIZE); |
| 974 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 975 | /* We're under lguest, paravirt is enabled, and we're running at |
| 976 | * privilege level 1, not 0 as normal. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 977 | paravirt_ops.name = "lguest"; |
| 978 | paravirt_ops.paravirt_enabled = 1; |
| 979 | paravirt_ops.kernel_rpl = 1; |
| 980 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 981 | /* We set up all the lguest overrides for sensitive operations. These |
| 982 | * are detailed with the operations themselves. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 983 | paravirt_ops.save_fl = save_fl; |
| 984 | paravirt_ops.restore_fl = restore_fl; |
| 985 | paravirt_ops.irq_disable = irq_disable; |
| 986 | paravirt_ops.irq_enable = irq_enable; |
| 987 | paravirt_ops.load_gdt = lguest_load_gdt; |
| 988 | paravirt_ops.memory_setup = lguest_memory_setup; |
| 989 | paravirt_ops.cpuid = lguest_cpuid; |
| 990 | paravirt_ops.write_cr3 = lguest_write_cr3; |
| 991 | paravirt_ops.flush_tlb_user = lguest_flush_tlb_user; |
| 992 | paravirt_ops.flush_tlb_single = lguest_flush_tlb_single; |
| 993 | paravirt_ops.flush_tlb_kernel = lguest_flush_tlb_kernel; |
| 994 | paravirt_ops.set_pte = lguest_set_pte; |
| 995 | paravirt_ops.set_pte_at = lguest_set_pte_at; |
| 996 | paravirt_ops.set_pmd = lguest_set_pmd; |
| 997 | #ifdef CONFIG_X86_LOCAL_APIC |
| 998 | paravirt_ops.apic_write = lguest_apic_write; |
| 999 | paravirt_ops.apic_write_atomic = lguest_apic_write; |
| 1000 | paravirt_ops.apic_read = lguest_apic_read; |
| 1001 | #endif |
| 1002 | paravirt_ops.load_idt = lguest_load_idt; |
| 1003 | paravirt_ops.iret = lguest_iret; |
| 1004 | paravirt_ops.load_esp0 = lguest_load_esp0; |
| 1005 | paravirt_ops.load_tr_desc = lguest_load_tr_desc; |
| 1006 | paravirt_ops.set_ldt = lguest_set_ldt; |
| 1007 | paravirt_ops.load_tls = lguest_load_tls; |
| 1008 | paravirt_ops.set_debugreg = lguest_set_debugreg; |
| 1009 | paravirt_ops.clts = lguest_clts; |
| 1010 | paravirt_ops.read_cr0 = lguest_read_cr0; |
| 1011 | paravirt_ops.write_cr0 = lguest_write_cr0; |
| 1012 | paravirt_ops.init_IRQ = lguest_init_IRQ; |
| 1013 | paravirt_ops.read_cr2 = lguest_read_cr2; |
| 1014 | paravirt_ops.read_cr3 = lguest_read_cr3; |
| 1015 | paravirt_ops.read_cr4 = lguest_read_cr4; |
| 1016 | paravirt_ops.write_cr4 = lguest_write_cr4; |
| 1017 | paravirt_ops.write_gdt_entry = lguest_write_gdt_entry; |
| 1018 | paravirt_ops.write_idt_entry = lguest_write_idt_entry; |
| 1019 | paravirt_ops.patch = lguest_patch; |
| 1020 | paravirt_ops.safe_halt = lguest_safe_halt; |
| 1021 | paravirt_ops.get_wallclock = lguest_get_wallclock; |
| 1022 | paravirt_ops.time_init = lguest_time_init; |
| 1023 | paravirt_ops.set_lazy_mode = lguest_lazy_mode; |
| 1024 | paravirt_ops.wbinvd = lguest_wbinvd; |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1025 | /* Now is a good time to look at the implementations of these functions |
| 1026 | * before returning to the rest of lguest_init(). */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1027 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1028 | /*G:070 Now we've seen all the paravirt_ops, we return to |
| 1029 | * lguest_init() where the rest of the fairly chaotic boot setup |
| 1030 | * occurs. |
| 1031 | * |
| 1032 | * The Host expects our first hypercall to tell it where our "struct |
| 1033 | * lguest_data" is, so we do that first. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1034 | hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0); |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1035 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1036 | /* The native boot code sets up initial page tables immediately after |
| 1037 | * the kernel itself, and sets init_pg_tables_end so they're not |
| 1038 | * clobbered. The Launcher places our initial pagetables somewhere at |
| 1039 | * the top of our physical memory, so we don't need extra space: set |
| 1040 | * init_pg_tables_end to the end of the kernel. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1041 | init_pg_tables_end = __pa(pg0); |
| 1042 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1043 | /* Load the %fs segment register (the per-cpu segment register) with |
| 1044 | * the normal data segment to get through booting. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1045 | asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory"); |
| 1046 | |
Rusty Russell | a8a11f0 | 2007-07-27 13:35:43 +1000 | [diff] [blame] | 1047 | /* Clear the part of the kernel data which is expected to be zero. |
| 1048 | * Normally it will be anyway, but if we're loading from a bzImage with |
| 1049 | * CONFIG_RELOCATALE=y, the relocations will be sitting here. */ |
| 1050 | memset(__bss_start, 0, __bss_stop - __bss_start); |
| 1051 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1052 | /* The Host uses the top of the Guest's virtual address space for the |
| 1053 | * Host<->Guest Switcher, and it tells us how much it needs in |
| 1054 | * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1055 | reserve_top_address(lguest_data.reserve_mem); |
| 1056 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1057 | /* If we don't initialize the lock dependency checker now, it crashes |
| 1058 | * paravirt_disable_iospace. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1059 | lockdep_init(); |
| 1060 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1061 | /* The IDE code spends about 3 seconds probing for disks: if we reserve |
| 1062 | * all the I/O ports up front it can't get them and so doesn't probe. |
| 1063 | * Other device drivers are similar (but less severe). This cuts the |
| 1064 | * kernel boot time on my machine from 4.1 seconds to 0.45 seconds. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1065 | paravirt_disable_iospace(); |
| 1066 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1067 | /* This is messy CPU setup stuff which the native boot code does before |
| 1068 | * start_kernel, so we have to do, too: */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1069 | cpu_detect(&new_cpu_data); |
| 1070 | /* head.S usually sets up the first capability word, so do it here. */ |
| 1071 | new_cpu_data.x86_capability[0] = cpuid_edx(1); |
| 1072 | |
| 1073 | /* Math is always hard! */ |
| 1074 | new_cpu_data.hard_math = 1; |
| 1075 | |
| 1076 | #ifdef CONFIG_X86_MCE |
| 1077 | mce_disabled = 1; |
| 1078 | #endif |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1079 | #ifdef CONFIG_ACPI |
| 1080 | acpi_disabled = 1; |
| 1081 | acpi_ht = 0; |
| 1082 | #endif |
| 1083 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1084 | /* We set the perferred console to "hvc". This is the "hypervisor |
| 1085 | * virtual console" driver written by the PowerPC people, which we also |
| 1086 | * adapted for lguest's use. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1087 | add_preferred_console("hvc", 0, NULL); |
| 1088 | |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1089 | /* Last of all, we set the power management poweroff hook to point to |
| 1090 | * the Guest routine to power off. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1091 | pm_power_off = lguest_power_off; |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1092 | |
| 1093 | /* Now we're set up, call start_kernel() in init/main.c and we proceed |
| 1094 | * to boot as normal. It never returns. */ |
Rusty Russell | 07ad157 | 2007-07-19 01:49:22 -0700 | [diff] [blame] | 1095 | start_kernel(); |
| 1096 | } |
Rusty Russell | b2b47c2 | 2007-07-26 10:41:02 -0700 | [diff] [blame] | 1097 | /* |
| 1098 | * This marks the end of stage II of our journey, The Guest. |
| 1099 | * |
| 1100 | * It is now time for us to explore the nooks and crannies of the three Guest |
| 1101 | * devices and complete our understanding of the Guest in "make Drivers". |
| 1102 | */ |