#include <linux/uaccess.h>
#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 enabled
(it's always 1, since irqs are enabled when guest is running). */
eflags = lg->regs->eflags;
if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0
&& !(irq_enable & X86_EFLAGS_IF))
eflags &= ~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;
}
