X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=arch%2Fx86%2Flguest%2Fboot.c;h=960a8d9c049c697e8505e003e96e7cffcd089f86;hb=6db6a5f3ae2ca6b874b0fd97ae16fdc9b5cdd6cc;hp=c751e3c03e85434b83f2caf73cd029f92f3b8dac;hpb=faca62273b602ab482fb7d3d940dbf41ef08b00e;p=safe%2Fjmp%2Flinux-2.6 diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index c751e3c..960a8d9 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -10,21 +10,19 @@ * (such as the example in Documentation/lguest/lguest.c) is called the * Launcher. * - * Secondly, we only run specially modified Guests, not normal kernels. When - * you set CONFIG_LGUEST to 'y' or 'm', this automatically sets - * CONFIG_LGUEST_GUEST=y, which compiles this file into the kernel so it knows - * how to be a Guest. This means that you can use the same kernel you boot - * normally (ie. as a Host) as a Guest. + * Secondly, we only run specially modified Guests, not normal kernels: setting + * CONFIG_LGUEST_GUEST to "y" compiles this file into the kernel so it knows + * how to be a Guest at boot time. This means that you can use the same kernel + * you boot normally (ie. as a Host) as a Guest. * * These Guests know that they cannot do privileged operations, such as disable * interrupts, and that they have to ask the Host to do such things explicitly. * This file consists of all the replacements for such low-level native * hardware operations: these special Guest versions call the Host. * - * So how does the kernel know it's a Guest? The Guest starts at a special - * entry point marked with a magic string, which sets up a few things then - * calls here. We replace the native functions various "paravirt" structures - * with our Guest versions, then boot like normal. :*/ + * So how does the kernel know it's a Guest? We'll see that later, but let's + * just say that we end up here where we replace the native functions various + * "paravirt" structures with our Guest versions, then boot like normal. :*/ /* * Copyright (C) 2006, Rusty Russell IBM Corporation. @@ -57,6 +55,8 @@ #include #include #include +#include +#include #include #include #include @@ -67,6 +67,7 @@ #include #include #include +#include /* for struct machine_ops */ /*G:010 Welcome to the Guest! * @@ -74,15 +75,6 @@ * behaving in simplified but equivalent ways. In particular, the Guest is the * same kernel as the Host (or at least, built from the same source code). :*/ -/* Declarations for definitions in lguest_guest.S */ -extern char lguest_noirq_start[], lguest_noirq_end[]; -extern const char lgstart_cli[], lgend_cli[]; -extern const char lgstart_sti[], lgend_sti[]; -extern const char lgstart_popf[], lgend_popf[]; -extern const char lgstart_pushf[], lgend_pushf[]; -extern const char lgstart_iret[], lgend_iret[]; -extern void lguest_iret(void); - struct lguest_data lguest_data = { .hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF }, .noirq_start = (u32)lguest_noirq_start, @@ -91,7 +83,6 @@ struct lguest_data lguest_data = { .blocked_interrupts = { 1 }, /* Block timer interrupts */ .syscall_vec = SYSCALL_VECTOR, }; -static cycle_t clock_base; /*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a * ring buffer of stored hypercalls which the Host will run though next time we @@ -142,7 +133,7 @@ static void async_hcall(unsigned long call, unsigned long arg1, * lguest_leave_lazy_mode(). * * So, when we're in lazy mode, we call async_hcall() to store the call for - * future processing. */ + * future processing: */ static void lazy_hcall(unsigned long call, unsigned long arg1, unsigned long arg2, @@ -155,7 +146,7 @@ static void lazy_hcall(unsigned long call, } /* When lazy mode is turned off reset the per-cpu lazy mode variable and then - * issue a hypercall to flush any stored calls. */ + * issue the do-nothing hypercall to flush any stored calls. */ static void lguest_leave_lazy_mode(void) { paravirt_leave_lazy(paravirt_get_lazy_mode()); @@ -172,7 +163,7 @@ static void lguest_leave_lazy_mode(void) * * So instead we keep an "irq_enabled" field inside our "struct lguest_data", * which the Guest can update with a single instruction. The Host knows to - * check there when it wants to deliver an interrupt. + * check there before it tries to deliver an interrupt. */ /* save_flags() is expected to return the processor state (ie. "flags"). The @@ -204,10 +195,15 @@ static void irq_enable(void) /*M:003 Note that we don't check for outstanding interrupts when we re-enable * them (or when we unmask an interrupt). This seems to work for the moment, * since interrupts are rare and we'll just get the interrupt on the next timer - * tick, but when we turn on CONFIG_NO_HZ, we should revisit this. One way + * tick, but now we can run with CONFIG_NO_HZ, we should revisit this. One way * would be to put the "irq_enabled" field in a page by itself, and have the * Host write-protect it when an interrupt comes in when irqs are disabled. - * There will then be a page fault as soon as interrupts are re-enabled. :*/ + * There will then be a page fault as soon as interrupts are re-enabled. + * + * A better method is to implement soft interrupt disable generally for x86: + * instead of disabling interrupts, we set a flag. If an interrupt does come + * in, we then disable them for real. This is uncommon, so we could simply use + * a hypercall for interrupt control and not worry about efficiency. :*/ /*G:034 * The Interrupt Descriptor Table (IDT). @@ -217,19 +213,24 @@ static void irq_enable(void) * address of the handler, and... well, who cares? The Guest just asks the * Host to make the change anyway, because the Host controls the real IDT. */ -static void lguest_write_idt_entry(struct desc_struct *dt, - int entrynum, u32 low, u32 high) +static void lguest_write_idt_entry(gate_desc *dt, + int entrynum, const gate_desc *g) { + /* The gate_desc structure is 8 bytes long: we hand it to the Host in + * two 32-bit chunks. The whole 32-bit kernel used to hand descriptors + * around like this; typesafety wasn't a big concern in Linux's early + * years. */ + u32 *desc = (u32 *)g; /* Keep the local copy up to date. */ - write_dt_entry(dt, entrynum, low, high); + native_write_idt_entry(dt, entrynum, g); /* Tell Host about this new entry. */ - hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, low, high); + hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]); } /* Changing to a different IDT is very rare: we keep the IDT up-to-date every * time it is written, so we can simply loop through all entries and tell the * Host about them. */ -static void lguest_load_idt(const struct Xgt_desc_struct *desc) +static void lguest_load_idt(const struct desc_ptr *desc) { unsigned int i; struct desc_struct *idt = (void *)desc->address; @@ -250,9 +251,10 @@ static void lguest_load_idt(const struct Xgt_desc_struct *desc) * * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY * hypercall and use that repeatedly to load a new IDT. I don't think it - * really matters, but wouldn't it be nice if they were the same? + * really matters, but wouldn't it be nice if they were the same? Wouldn't + * it be even better if you were the one to send the patch to fix it? */ -static void lguest_load_gdt(const struct Xgt_desc_struct *desc) +static void lguest_load_gdt(const struct desc_ptr *desc) { BUG_ON((desc->size+1)/8 != GDT_ENTRIES); hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0); @@ -261,10 +263,10 @@ static void lguest_load_gdt(const struct Xgt_desc_struct *desc) /* For a single GDT entry which changes, we do the lazy thing: alter our GDT, * then tell the Host to reload the entire thing. This operation is so rare * that this naive implementation is reasonable. */ -static void lguest_write_gdt_entry(struct desc_struct *dt, - int entrynum, u32 low, u32 high) +static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum, + const void *desc, int type) { - write_dt_entry(dt, entrynum, low, high); + native_write_gdt_entry(dt, entrynum, desc, type); hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0); } @@ -305,9 +307,9 @@ static void lguest_load_tr_desc(void) /* The "cpuid" instruction is a way of querying both the CPU identity * (manufacturer, model, etc) and its features. It was introduced before the - * Pentium in 1993 and keeps getting extended by both Intel and AMD. As you - * might imagine, after a decade and a half this treatment, it is now a giant - * ball of hair. Its entry in the current Intel manual runs to 28 pages. + * Pentium in 1993 and keeps getting extended by both Intel, AMD and others. + * As you might imagine, after a decade and a half this treatment, it is now a + * giant ball of hair. Its entry in the current Intel manual runs to 28 pages. * * This instruction even it has its own Wikipedia entry. The Wikipedia entry * has been translated into 4 languages. I am not making this up! @@ -333,14 +335,19 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx, case 1: /* Basic feature request. */ /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */ *cx &= 0x00002201; - /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, FPU. */ - *dx &= 0x07808101; + /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU. */ + *dx &= 0x07808111; /* The Host can do a nice optimization if it knows that the * kernel mappings (addresses above 0xC0000000 or whatever * PAGE_OFFSET is set to) haven't changed. But Linux calls * flush_tlb_user() for both user and kernel mappings unless * the Page Global Enable (PGE) feature bit is set. */ *dx |= 0x00002000; + /* We also lie, and say we're family id 5. 6 or greater + * leads to a rdmsr in early_init_intel which we can't handle. + * Family ID is returned as bits 8-12 in ax. */ + *ax &= 0xFFFFF0FF; + *ax |= 0x00000500; break; case 0x80000000: /* Futureproof this a little: if they ask how much extended @@ -365,10 +372,9 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx, * lazily after a task switch, and Linux uses that gratefully, but wouldn't a * name like "FPUTRAP bit" be a little less cryptic? * - * We store cr0 (and cr3) locally, because the Host never changes it. The - * Guest sometimes wants to read it and we'd prefer not to bother the Host - * unnecessarily. */ -static unsigned long current_cr0, current_cr3; + * We store cr0 locally because the Host never changes it. The Guest sometimes + * wants to read it and we'd prefer not to bother the Host unnecessarily. */ +static unsigned long current_cr0; static void lguest_write_cr0(unsigned long val) { lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0); @@ -397,17 +403,23 @@ static unsigned long lguest_read_cr2(void) return lguest_data.cr2; } +/* See lguest_set_pte() below. */ +static bool cr3_changed = false; + /* cr3 is the current toplevel pagetable page: the principle is the same as - * cr0. Keep a local copy, and tell the Host when it changes. */ + * cr0. Keep a local copy, and tell the Host when it changes. The only + * difference is that our local copy is in lguest_data because the Host needs + * to set it upon our initial hypercall. */ static void lguest_write_cr3(unsigned long cr3) { + lguest_data.pgdir = cr3; lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0); - current_cr3 = cr3; + cr3_changed = true; } static unsigned long lguest_read_cr3(void) { - return current_cr3; + return lguest_data.pgdir; } /* cr4 is used to enable and disable PGE, but we don't care. */ @@ -496,13 +508,13 @@ static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval) * to forget all of them. Fortunately, this is very rare. * * ... except in early boot when the kernel sets up the initial pagetables, - * which makes booting astonishingly slow. So we don't even tell the Host - * anything changed until we've done the first page table switch. */ + * which makes booting astonishingly slow: 1.83 seconds! So we don't even tell + * the Host anything changed until we've done the first page table switch, + * which brings boot back to 0.25 seconds. */ static void lguest_set_pte(pte_t *ptep, pte_t pteval) { *ptep = pteval; - /* Don't bother with hypercall before initial setup. */ - if (current_cr3) + if (cr3_changed) lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0); } @@ -519,7 +531,7 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval) static void lguest_flush_tlb_single(unsigned long addr) { /* Simply set it to zero: if it was not, it will fault back in. */ - lazy_hcall(LHCALL_SET_PTE, current_cr3, addr, 0); + lazy_hcall(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0); } /* This is what happens after the Guest has removed a large number of entries. @@ -579,17 +591,24 @@ static void __init lguest_init_IRQ(void) for (i = 0; i < LGUEST_IRQS; i++) { int vector = FIRST_EXTERNAL_VECTOR + i; - if (vector != SYSCALL_VECTOR) { + /* Some systems map "vectors" to interrupts weirdly. Lguest has + * a straightforward 1 to 1 mapping, so force that here. */ + __get_cpu_var(vector_irq)[vector] = i; + if (vector != SYSCALL_VECTOR) set_intr_gate(vector, interrupt[i]); - set_irq_chip_and_handler(i, &lguest_irq_controller, - handle_level_irq); - } } /* This call is required to set up for 4k stacks, where we have * separate stacks for hard and soft interrupts. */ irq_ctx_init(smp_processor_id()); } +void lguest_setup_irq(unsigned int irq) +{ + irq_to_desc_alloc_cpu(irq, 0); + set_irq_chip_and_handler_name(irq, &lguest_irq_controller, + handle_level_irq, "level"); +} + /* * Time. * @@ -601,19 +620,25 @@ static unsigned long lguest_get_wallclock(void) return lguest_data.time.tv_sec; } +/* The TSC is an Intel thing called the Time Stamp Counter. The Host tells us + * what speed it runs at, or 0 if it's unusable as a reliable clock source. + * This matches what we want here: if we return 0 from this function, the x86 + * TSC clock will give up and not register itself. */ +static unsigned long lguest_tsc_khz(void) +{ + return lguest_data.tsc_khz; +} + +/* If we can't use the TSC, the kernel falls back to our lower-priority + * "lguest_clock", where we read the time value given to us by the Host. */ static cycle_t lguest_clock_read(void) { unsigned long sec, nsec; - /* If the Host tells the TSC speed, we can trust that. */ - if (lguest_data.tsc_khz) - return native_read_tsc(); - - /* If we can't use the TSC, we read the time value written by the Host. - * Since it's in two parts (seconds and nanoseconds), we risk reading - * it just as it's changing from 99 & 0.999999999 to 100 and 0, and - * getting 99 and 0. As Linux tends to come apart under the stress of - * time travel, we must be careful: */ + /* Since the time is in two parts (seconds and nanoseconds), we risk + * reading it just as it's changing from 99 & 0.999999999 to 100 and 0, + * and getting 99 and 0. As Linux tends to come apart under the stress + * of time travel, we must be careful: */ do { /* First we read the seconds part. */ sec = lguest_data.time.tv_sec; @@ -628,14 +653,14 @@ static cycle_t lguest_clock_read(void) /* Now if the seconds part has changed, try again. */ } while (unlikely(lguest_data.time.tv_sec != sec)); - /* Our non-TSC clock is in real nanoseconds. */ + /* Our lguest clock is in real nanoseconds. */ return sec*1000000000ULL + nsec; } -/* This is what we tell the kernel is our clocksource. */ +/* This is the fallback clocksource: lower priority than the TSC clocksource. */ static struct clocksource lguest_clock = { .name = "lguest", - .rating = 400, + .rating = 200, .read = lguest_clock_read, .mask = CLOCKSOURCE_MASK(64), .mult = 1 << 22, @@ -643,24 +668,22 @@ static struct clocksource lguest_clock = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; -/* The "scheduler clock" is just our real clock, adjusted to start at zero */ -static unsigned long long lguest_sched_clock(void) -{ - return cyc2ns(&lguest_clock, lguest_clock_read() - clock_base); -} - /* We also need a "struct clock_event_device": Linux asks us to set it to go * off some time in the future. Actually, James Morris figured all this out, I * just applied the patch. */ static int lguest_clockevent_set_next_event(unsigned long delta, struct clock_event_device *evt) { + /* FIXME: I don't think this can ever happen, but James tells me he had + * to put this code in. Maybe we should remove it now. Anyone? */ if (delta < LG_CLOCK_MIN_DELTA) { if (printk_ratelimit()) printk(KERN_DEBUG "%s: small delta %lu ns\n", - __FUNCTION__, delta); + __func__, delta); return -ETIME; } + + /* Please wake us this far in the future. */ hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0); return 0; } @@ -718,22 +741,11 @@ static void lguest_time_init(void) /* Set up the timer interrupt (0) to go to our simple timer routine */ set_irq_handler(0, lguest_time_irq); - /* Our clock structure looks like arch/x86/kernel/tsc_32.c if we can - * use the TSC, otherwise it's a dumb nanosecond-resolution clock. - * Either way, the "rating" is set so high that it's always chosen over - * any other clocksource. */ - if (lguest_data.tsc_khz) - lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz, - lguest_clock.shift); - clock_base = lguest_clock_read(); clocksource_register(&lguest_clock); - /* Now we've set up our clock, we can use it as the scheduler clock */ - pv_time_ops.sched_clock = lguest_sched_clock; - /* We can't set cpumask in the initializer: damn C limitations! Set it * here and register our timer device. */ - lguest_clockevent.cpumask = cpumask_of_cpu(0); + lguest_clockevent.cpumask = cpumask_of(0); clockevents_register_device(&lguest_clockevent); /* Finally, we unblock the timer interrupt. */ @@ -756,7 +768,7 @@ static void lguest_time_init(void) * will not tolerate us trying to use that), the stack pointer, and the number * of pages in the stack. */ static void lguest_load_sp0(struct tss_struct *tss, - struct thread_struct *thread) + struct thread_struct *thread) { lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->sp0, THREAD_SIZE/PAGE_SIZE); @@ -788,14 +800,44 @@ static void lguest_wbinvd(void) * code qualifies for Advanced. It will also never interrupt anything. It * does, however, allow us to get through the Linux boot code. */ #ifdef CONFIG_X86_LOCAL_APIC -static void lguest_apic_write(unsigned long reg, u32 v) +static void lguest_apic_write(u32 reg, u32 v) { } -static u32 lguest_apic_read(unsigned long reg) +static u32 lguest_apic_read(u32 reg) { return 0; } + +static u64 lguest_apic_icr_read(void) +{ + return 0; +} + +static void lguest_apic_icr_write(u32 low, u32 id) +{ + /* Warn to see if there's any stray references */ + WARN_ON(1); +} + +static void lguest_apic_wait_icr_idle(void) +{ + return; +} + +static u32 lguest_apic_safe_wait_icr_idle(void) +{ + return 0; +} + +static struct apic_ops lguest_basic_apic_ops = { + .read = lguest_apic_read, + .write = lguest_apic_write, + .icr_read = lguest_apic_icr_read, + .icr_write = lguest_apic_icr_write, + .wait_icr_idle = lguest_apic_wait_icr_idle, + .safe_wait_icr_idle = lguest_apic_safe_wait_icr_idle, +}; #endif /* STOP! Until an interrupt comes in. */ @@ -804,15 +846,14 @@ static void lguest_safe_halt(void) hcall(LHCALL_HALT, 0, 0, 0); } -/* Perhaps CRASH isn't the best name for this hypercall, but we use it to get a - * message out when we're crashing as well as elegant termination like powering - * off. +/* The SHUTDOWN hypercall takes a string to describe what's happening, and + * an argument which says whether this to restart (reboot) the Guest or not. * * Note that the Host always prefers that the Guest speak in physical addresses * rather than virtual addresses, so we use __pa() here. */ static void lguest_power_off(void) { - hcall(LHCALL_CRASH, __pa("Power down"), 0, 0); + hcall(LHCALL_SHUTDOWN, __pa("Power down"), LGUEST_SHUTDOWN_POWEROFF, 0); } /* @@ -822,7 +863,7 @@ static void lguest_power_off(void) */ static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p) { - hcall(LHCALL_CRASH, __pa(p), 0, 0); + hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0); /* The hcall won't return, but to keep gcc happy, we're "done". */ return NOTIFY_DONE; } @@ -834,13 +875,14 @@ static struct notifier_block paniced = { /* Setting up memory is fairly easy. */ static __init char *lguest_memory_setup(void) { - /* We do this here and not earlier because lockcheck barfs if we do it - * before start_kernel() */ + /* We do this here and not earlier because lockcheck used to barf if we + * did it before start_kernel(). I think we fixed that, so it'd be + * nice to move it back to lguest_init. Patch welcome... */ atomic_notifier_chain_register(&panic_notifier_list, &paniced); /* The Linux bootloader header contains an "e820" memory map: the * Launcher populated the first entry with our memory limit. */ - add_memory_region(boot_params.e820_map[0].addr, + e820_add_region(boot_params.e820_map[0].addr, boot_params.e820_map[0].size, boot_params.e820_map[0].type); @@ -868,12 +910,19 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count) return len; } +/* Rebooting also tells the Host we're finished, but the RESTART flag tells the + * Launcher to reboot us. */ +static void lguest_restart(char *reason) +{ + hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0); +} + /*G:050 * Patching (Powerfully Placating Performance Pedants) * - * We have already seen that pv_ops structures let us replace simple - * native instructions with calls to the appropriate back end all throughout - * the kernel. This allows the same kernel to run as a Guest and as a native + * We have already seen that pv_ops structures let us replace simple native + * instructions with calls to the appropriate back end all throughout the + * kernel. This allows the same kernel to run as a Guest and as a native * kernel, but it's slow because of all the indirect branches. * * Remember that David Wheeler quote about "Any problem in computer science can @@ -889,7 +938,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count) * that we can fit comfortably. * * First we need assembly templates of each of the patchable Guest operations, - * and these are in lguest_asm.S. */ + * and these are in i386_head.S. */ /*G:060 We construct a table from the assembler templates: */ static const struct lguest_insns @@ -926,9 +975,9 @@ static unsigned lguest_patch(u8 type, u16 clobber, void *ibuf, return insn_len; } -/*G:030 Once we get to lguest_init(), we know we're a Guest. The pv_ops - * structures in the kernel provide points for (almost) every routine we have - * to override to avoid privileged instructions. */ +/*G:030 Once we get to lguest_init(), we know we're a Guest. The various + * pv_ops structures in the kernel provide points for (almost) every routine we + * have to override to avoid privileged instructions. */ __init void lguest_init(void) { /* We're under lguest, paravirt is enabled, and we're running at @@ -988,14 +1037,13 @@ __init void lguest_init(void) #ifdef CONFIG_X86_LOCAL_APIC /* apic read/write intercepts */ - pv_apic_ops.apic_write = lguest_apic_write; - pv_apic_ops.apic_write_atomic = lguest_apic_write; - pv_apic_ops.apic_read = lguest_apic_read; + apic_ops = &lguest_basic_apic_ops; #endif /* time operations */ pv_time_ops.get_wallclock = lguest_get_wallclock; pv_time_ops.time_init = lguest_time_init; + pv_time_ops.get_tsc_khz = lguest_tsc_khz; /* Now is a good time to look at the implementations of these functions * before returning to the rest of lguest_init(). */ @@ -1009,15 +1057,19 @@ __init void lguest_init(void) * clobbered. The Launcher places our initial pagetables somewhere at * the top of our physical memory, so we don't need extra space: set * init_pg_tables_end to the end of the kernel. */ + init_pg_tables_start = __pa(pg0); init_pg_tables_end = __pa(pg0); + /* As described in head_32.S, we map the first 128M of memory. */ + max_pfn_mapped = (128*1024*1024) >> PAGE_SHIFT; + /* Load the %fs segment register (the per-cpu segment register) with * the normal data segment to get through booting. */ asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory"); - /* The Host uses the top of the Guest's virtual address space for the - * Host<->Guest Switcher, and it tells us how big that is in - * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */ + /* The Host<->Guest Switcher lives at the top of our address space, and + * the Host told us how big it is when we made LGUEST_INIT hypercall: + * it put the answer in lguest_data.reserve_mem */ reserve_top_address(lguest_data.reserve_mem); /* If we don't initialize the lock dependency checker now, it crashes @@ -1039,6 +1091,7 @@ __init void lguest_init(void) /* Math is always hard! */ new_cpu_data.hard_math = 1; + /* We don't have features. We have puppies! Puppies! */ #ifdef CONFIG_X86_MCE mce_disabled = 1; #endif @@ -1047,7 +1100,7 @@ __init void lguest_init(void) acpi_ht = 0; #endif - /* We set the perferred console to "hvc". This is the "hypervisor + /* We set the preferred console to "hvc". This is the "hypervisor * virtual console" driver written by the PowerPC people, which we also * adapted for lguest's use. */ add_preferred_console("hvc", 0, NULL); @@ -1056,12 +1109,14 @@ __init void lguest_init(void) virtio_cons_early_init(early_put_chars); /* Last of all, we set the power management poweroff hook to point to - * the Guest routine to power off. */ + * the Guest routine to power off, and the reboot hook to our restart + * routine. */ pm_power_off = lguest_power_off; + machine_ops.restart = lguest_restart; - /* Now we're set up, call start_kernel() in init/main.c and we proceed + /* Now we're set up, call i386_start_kernel() in head32.c and we proceed * to boot as normal. It never returns. */ - start_kernel(); + i386_start_kernel(); } /* * This marks the end of stage II of our journey, The Guest.