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 <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
new file mode 100644
index 0000000..d9de5bb
--- /dev/null
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -0,0 +1,268 @@
+#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 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;
+}
