From d7e28ffe6c74416b54345d6004fd0964c115b12c Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 19 Jul 2007 01:49:23 -0700 Subject: lguest: the host code This is the code for the "lg.ko" module, which allows lguest guests to be launched. [akpm@linux-foundation.org: update for futex-new-private-futexes] [akpm@linux-foundation.org: build fix] [jmorris@namei.org: lguest: use hrtimers] [akpm@linux-foundation.org: x86_64 build fix] Signed-off-by: Rusty Russell Cc: Andi Kleen Cc: Eric Dumazet Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/lguest/interrupts_and_traps.c | 268 ++++++++++++++++++++++++++++++++++ 1 file changed, 268 insertions(+) create mode 100644 drivers/lguest/interrupts_and_traps.c (limited to 'drivers/lguest/interrupts_and_traps.c') diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c new file mode 100644 index 00000000000..d9de5bbc613 --- /dev/null +++ b/drivers/lguest/interrupts_and_traps.c @@ -0,0 +1,268 @@ +#include +#include "lg.h" + +static unsigned long idt_address(u32 lo, u32 hi) +{ + return (lo & 0x0000FFFF) | (hi & 0xFFFF0000); +} + +static int idt_type(u32 lo, u32 hi) +{ + return (hi >> 8) & 0xF; +} + +static int idt_present(u32 lo, u32 hi) +{ + return (hi & 0x8000); +} + +static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val) +{ + *gstack -= 4; + lgwrite_u32(lg, *gstack, val); +} + +static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) +{ + unsigned long gstack; + u32 eflags, ss, irq_enable; + + /* If they want a ring change, we use new stack and push old ss/esp */ + if ((lg->regs->ss&0x3) != GUEST_PL) { + gstack = guest_pa(lg, lg->esp1); + ss = lg->ss1; + push_guest_stack(lg, &gstack, lg->regs->ss); + push_guest_stack(lg, &gstack, lg->regs->esp); + } else { + gstack = guest_pa(lg, lg->regs->esp); + ss = lg->regs->ss; + } + + /* We use IF bit in eflags to indicate whether irqs were disabled + (it's always 0, since irqs are enabled when guest is running). */ + eflags = lg->regs->eflags; + if (get_user(irq_enable, &lg->lguest_data->irq_enabled)) + irq_enable = 0; + eflags |= (irq_enable & X86_EFLAGS_IF); + + push_guest_stack(lg, &gstack, eflags); + push_guest_stack(lg, &gstack, lg->regs->cs); + push_guest_stack(lg, &gstack, lg->regs->eip); + + if (has_err) + push_guest_stack(lg, &gstack, lg->regs->errcode); + + /* Change the real stack so switcher returns to trap handler */ + lg->regs->ss = ss; + lg->regs->esp = gstack + lg->page_offset; + lg->regs->cs = (__KERNEL_CS|GUEST_PL); + lg->regs->eip = idt_address(lo, hi); + + /* Disable interrupts for an interrupt gate. */ + if (idt_type(lo, hi) == 0xE) + if (put_user(0, &lg->lguest_data->irq_enabled)) + kill_guest(lg, "Disabling interrupts"); +} + +void maybe_do_interrupt(struct lguest *lg) +{ + unsigned int irq; + DECLARE_BITMAP(blk, LGUEST_IRQS); + struct desc_struct *idt; + + if (!lg->lguest_data) + return; + + /* Mask out any interrupts they have blocked. */ + if (copy_from_user(&blk, lg->lguest_data->blocked_interrupts, + sizeof(blk))) + return; + + bitmap_andnot(blk, lg->irqs_pending, blk, LGUEST_IRQS); + + irq = find_first_bit(blk, LGUEST_IRQS); + if (irq >= LGUEST_IRQS) + return; + + if (lg->regs->eip >= lg->noirq_start && lg->regs->eip < lg->noirq_end) + return; + + /* If they're halted, we re-enable interrupts. */ + if (lg->halted) { + /* Re-enable interrupts. */ + if (put_user(X86_EFLAGS_IF, &lg->lguest_data->irq_enabled)) + kill_guest(lg, "Re-enabling interrupts"); + lg->halted = 0; + } else { + /* Maybe they have interrupts disabled? */ + u32 irq_enabled; + if (get_user(irq_enabled, &lg->lguest_data->irq_enabled)) + irq_enabled = 0; + if (!irq_enabled) + return; + } + + idt = &lg->idt[FIRST_EXTERNAL_VECTOR+irq]; + if (idt_present(idt->a, idt->b)) { + clear_bit(irq, lg->irqs_pending); + set_guest_interrupt(lg, idt->a, idt->b, 0); + } +} + +static int has_err(unsigned int trap) +{ + return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17); +} + +int deliver_trap(struct lguest *lg, unsigned int num) +{ + u32 lo = lg->idt[num].a, hi = lg->idt[num].b; + + if (!idt_present(lo, hi)) + return 0; + set_guest_interrupt(lg, lo, hi, has_err(num)); + return 1; +} + +static int direct_trap(const struct lguest *lg, + const struct desc_struct *trap, + unsigned int num) +{ + /* Hardware interrupts don't go to guest (except syscall). */ + if (num >= FIRST_EXTERNAL_VECTOR && num != SYSCALL_VECTOR) + return 0; + + /* We intercept page fault (demand shadow paging & cr2 saving) + protection fault (in/out emulation) and device not + available (TS handling), and hypercall */ + if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY) + return 0; + + /* Interrupt gates (0xE) or not present (0x0) can't go direct. */ + return idt_type(trap->a, trap->b) == 0xF; +} + +void pin_stack_pages(struct lguest *lg) +{ + unsigned int i; + + for (i = 0; i < lg->stack_pages; i++) + pin_page(lg, lg->esp1 - i * PAGE_SIZE); +} + +void guest_set_stack(struct lguest *lg, u32 seg, u32 esp, unsigned int pages) +{ + /* You cannot have a stack segment with priv level 0. */ + if ((seg & 0x3) != GUEST_PL) + kill_guest(lg, "bad stack segment %i", seg); + if (pages > 2) + kill_guest(lg, "bad stack pages %u", pages); + lg->ss1 = seg; + lg->esp1 = esp; + lg->stack_pages = pages; + pin_stack_pages(lg); +} + +/* Set up trap in IDT. */ +static void set_trap(struct lguest *lg, struct desc_struct *trap, + unsigned int num, u32 lo, u32 hi) +{ + u8 type = idt_type(lo, hi); + + if (!idt_present(lo, hi)) { + trap->a = trap->b = 0; + return; + } + + if (type != 0xE && type != 0xF) + kill_guest(lg, "bad IDT type %i", type); + + trap->a = ((__KERNEL_CS|GUEST_PL)<<16) | (lo&0x0000FFFF); + trap->b = (hi&0xFFFFEF00); +} + +void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi) +{ + /* Guest never handles: NMI, doublefault, hypercall, spurious irq. */ + if (num == 2 || num == 8 || num == 15 || num == LGUEST_TRAP_ENTRY) + return; + + lg->changed |= CHANGED_IDT; + if (num < ARRAY_SIZE(lg->idt)) + set_trap(lg, &lg->idt[num], num, lo, hi); + else if (num == SYSCALL_VECTOR) + set_trap(lg, &lg->syscall_idt, num, lo, hi); +} + +static void default_idt_entry(struct desc_struct *idt, + int trap, + const unsigned long handler) +{ + u32 flags = 0x8e00; + + /* They can't "int" into any of them except hypercall. */ + if (trap == LGUEST_TRAP_ENTRY) + flags |= (GUEST_PL << 13); + + idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF); + idt->b = (handler&0xFFFF0000) | flags; +} + +void setup_default_idt_entries(struct lguest_ro_state *state, + const unsigned long *def) +{ + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++) + default_idt_entry(&state->guest_idt[i], i, def[i]); +} + +void copy_traps(const struct lguest *lg, struct desc_struct *idt, + const unsigned long *def) +{ + unsigned int i; + + /* All hardware interrupts are same whatever the guest: only the + * traps might be different. */ + for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) { + if (direct_trap(lg, &lg->idt[i], i)) + idt[i] = lg->idt[i]; + else + default_idt_entry(&idt[i], i, def[i]); + } + i = SYSCALL_VECTOR; + if (direct_trap(lg, &lg->syscall_idt, i)) + idt[i] = lg->syscall_idt; + else + default_idt_entry(&idt[i], i, def[i]); +} + +void guest_set_clockevent(struct lguest *lg, unsigned long delta) +{ + ktime_t expires; + + if (unlikely(delta == 0)) { + /* Clock event device is shutting down. */ + hrtimer_cancel(&lg->hrt); + return; + } + + expires = ktime_add_ns(ktime_get_real(), delta); + hrtimer_start(&lg->hrt, expires, HRTIMER_MODE_ABS); +} + +static enum hrtimer_restart clockdev_fn(struct hrtimer *timer) +{ + struct lguest *lg = container_of(timer, struct lguest, hrt); + + set_bit(0, lg->irqs_pending); + if (lg->halted) + wake_up_process(lg->tsk); + return HRTIMER_NORESTART; +} + +void init_clockdev(struct lguest *lg) +{ + hrtimer_init(&lg->hrt, CLOCK_REALTIME, HRTIMER_MODE_ABS); + lg->hrt.function = clockdev_fn; +} -- cgit v1.2.3-70-g09d2