}
/* An IDT entry can't be used unless the "present" bit is set. */
-static int idt_present(u32 lo, u32 hi)
+static bool idt_present(u32 lo, u32 hi)
{
return (hi & 0x8000);
}
* We set up the stack just like the CPU does for a real interrupt, so it's
* identical for the Guest (and the standard "iret" instruction will undo
* it). */
-static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi, int has_err)
+static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
+ bool has_err)
{
unsigned long gstack, origstack;
u32 eflags, ss, irq_enable;
/* set_guest_interrupt() takes the interrupt descriptor and a
* flag to say whether this interrupt pushes an error code onto
* the stack as well: virtual interrupts never do. */
- set_guest_interrupt(cpu, idt->a, idt->b, 0);
+ set_guest_interrupt(cpu, idt->a, idt->b, false);
}
/* Every time we deliver an interrupt, we update the timestamp in the
int init_interrupts(void)
{
/* If they want some strange system call vector, reserve it now */
- if (syscall_vector != SYSCALL_VECTOR
- && test_and_set_bit(syscall_vector, used_vectors)) {
- printk("lg: couldn't reserve syscall %u\n", syscall_vector);
- return -EBUSY;
+ if (syscall_vector != SYSCALL_VECTOR) {
+ if (test_bit(syscall_vector, used_vectors) ||
+ vector_used_by_percpu_irq(syscall_vector)) {
+ printk(KERN_ERR "lg: couldn't reserve syscall %u\n",
+ syscall_vector);
+ return -EBUSY;
+ }
+ set_bit(syscall_vector, used_vectors);
}
+
return 0;
}
/*H:220 Now we've got the routines to deliver interrupts, delivering traps like
* page fault is easy. The only trick is that Intel decided that some traps
* should have error codes: */
-static int has_err(unsigned int trap)
+static bool has_err(unsigned int trap)
{
return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
}
/* deliver_trap() returns true if it could deliver the trap. */
-int deliver_trap(struct lg_cpu *cpu, unsigned int num)
+bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
{
/* Trap numbers are always 8 bit, but we set an impossible trap number
* for traps inside the Switcher, so check that here. */
if (num >= ARRAY_SIZE(cpu->arch.idt))
- return 0;
+ return false;
/* Early on the Guest hasn't set the IDT entries (or maybe it put a
* bogus one in): if we fail here, the Guest will be killed. */
if (!idt_present(cpu->arch.idt[num].a, cpu->arch.idt[num].b))
- return 0;
+ return false;
set_guest_interrupt(cpu, cpu->arch.idt[num].a,
cpu->arch.idt[num].b, has_err(num));
- return 1;
+ return true;
}
/*H:250 Here's the hard part: returning to the Host every time a trap happens
*
* This routine indicates if a particular trap number could be delivered
* directly. */
-static int direct_trap(unsigned int num)
+static bool direct_trap(unsigned int num)
{
/* Hardware interrupts don't go to the Guest at all (except system
* call). */
if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
- return 0;
+ return false;
/* The Host needs to see page faults (for shadow paging and to save the
* fault address), general protection faults (in/out emulation) and
- * device not available (TS handling), and of course, the hypercall
- * trap. */
- return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
+ * device not available (TS handling), invalid opcode fault (kvm hcall),
+ * and of course, the hypercall trap. */
+ return num != 14 && num != 13 && num != 7 &&
+ num != 6 && num != LGUEST_TRAP_ENTRY;
}
/*:*/
* deliver_trap() to bounce it back into the Guest. */
static void default_idt_entry(struct desc_struct *idt,
int trap,
- const unsigned long handler)
+ const unsigned long handler,
+ const struct desc_struct *base)
{
/* A present interrupt gate. */
u32 flags = 0x8e00;
* the Guest to use the "int" instruction to trigger it. */
if (trap == LGUEST_TRAP_ENTRY)
flags |= (GUEST_PL << 13);
+ else if (base)
+ /* Copy priv. level from what Guest asked for. This allows
+ * debug (int 3) traps from Guest userspace, for example. */
+ flags |= (base->b & 0x6000);
/* Now pack it into the IDT entry in its weird format. */
idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
unsigned int i;
for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++)
- default_idt_entry(&state->guest_idt[i], i, def[i]);
+ default_idt_entry(&state->guest_idt[i], i, def[i], NULL);
}
/*H:240 We don't use the IDT entries in the "struct lguest" directly, instead
/* We can simply copy the direct traps, otherwise we use the default
* ones in the Switcher: they will return to the Host. */
for (i = 0; i < ARRAY_SIZE(cpu->arch.idt); i++) {
+ const struct desc_struct *gidt = &cpu->arch.idt[i];
+
/* If no Guest can ever override this trap, leave it alone. */
if (!direct_trap(i))
continue;
/* Only trap gates (type 15) can go direct to the Guest.
* Interrupt gates (type 14) disable interrupts as they are
* entered, which we never let the Guest do. Not present
- * entries (type 0x0) also can't go direct, of course. */
- if (idt_type(cpu->arch.idt[i].a, cpu->arch.idt[i].b) == 0xF)
- idt[i] = cpu->arch.idt[i];
+ * entries (type 0x0) also can't go direct, of course.
+ *
+ * If it can't go direct, we still need to copy the priv. level:
+ * they might want to give userspace access to a software
+ * interrupt. */
+ if (idt_type(gidt->a, gidt->b) == 0xF)
+ idt[i] = *gidt;
else
- /* Reset it to the default. */
- default_idt_entry(&idt[i], i, def[i]);
+ default_idt_entry(&idt[i], i, def[i], gidt);
}
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff