diff options
| -rw-r--r-- | drivers/lguest/interrupts_and_traps.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c index 0414ddf8758..a1039068f95 100644 --- a/drivers/lguest/interrupts_and_traps.c +++ b/drivers/lguest/interrupts_and_traps.c @@ -406,7 +406,8 @@ void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int num, u32 lo, u32 hi) * 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; @@ -415,6 +416,10 @@ static void default_idt_entry(struct desc_struct *idt, * 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); @@ -428,7 +433,7 @@ void setup_default_idt_entries(struct lguest_ro_state *state, 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 @@ -442,6 +447,8 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt, /* 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; @@ -449,12 +456,15 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt, /* 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); } } |