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authorJan Kiszka <jan.kiszka@siemens.com>2013-03-19 12:36:51 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-04-05 10:16:38 -0700
commit0072625c351588b8fde9e6f46fb60ba2e521fb47 (patch)
tree5ede7ff405954501874d02b14a6c1042f04d6b0d
parent2e8e2c7847cc17a8135ad17869f5ba37207e2f89 (diff)
downloadlinux-linaro-stable-0072625c351588b8fde9e6f46fb60ba2e521fb47.tar.gz
KVM: x86: Prevent starting PIT timers in the absence of irqchip support
commit 0924ab2cfa98b1ece26c033d696651fd62896c69 upstream. User space may create the PIT and forgets about setting up the irqchips. In that case, firing PIT IRQs will crash the host: BUG: unable to handle kernel NULL pointer dereference at 0000000000000128 IP: [<ffffffffa10f6280>] kvm_set_irq+0x30/0x170 [kvm] ... Call Trace: [<ffffffffa11228c1>] pit_do_work+0x51/0xd0 [kvm] [<ffffffff81071431>] process_one_work+0x111/0x4d0 [<ffffffff81071bb2>] worker_thread+0x152/0x340 [<ffffffff81075c8e>] kthread+0x7e/0x90 [<ffffffff815a4474>] kernel_thread_helper+0x4/0x10 Prevent this by checking the irqchip mode before starting a timer. We can't deny creating the PIT if the irqchips aren't set up yet as current user land expects this order to work. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/i8254.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index efad72385058..43e04d128af4 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -338,11 +338,15 @@ static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
return HRTIMER_NORESTART;
}
-static void create_pit_timer(struct kvm_kpit_state *ps, u32 val, int is_period)
+static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
{
+ struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
struct kvm_timer *pt = &ps->pit_timer;
s64 interval;
+ if (!irqchip_in_kernel(kvm))
+ return;
+
interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
pr_debug("create pit timer, interval is %llu nsec\n", interval);
@@ -394,13 +398,13 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val)
/* FIXME: enhance mode 4 precision */
case 4:
if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {
- create_pit_timer(ps, val, 0);
+ create_pit_timer(kvm, val, 0);
}
break;
case 2:
case 3:
if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){
- create_pit_timer(ps, val, 1);
+ create_pit_timer(kvm, val, 1);
}
break;
default: