* [PATCH 1/2] KVM: x86: Prevent starting PIT timers in the absence of irqchip support
@ 2011-12-14 18:25 Jan Kiszka
2011-12-14 18:25 ` [PATCH 2/2] KVM: x86: Consolidate PIT legacy test Jan Kiszka
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kiszka @ 2011-12-14 18:25 UTC (permalink / raw)
To: Avi Kivity, Marcelo Tosatti; +Cc: kvm
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>
---
This is for stable, the next patch just a cleanup.
arch/x86/kvm/i8254.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 76e3f1c..405f262 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:
--
1.7.3.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/2] KVM: x86: Consolidate PIT legacy test
2011-12-14 18:25 [PATCH 1/2] KVM: x86: Prevent starting PIT timers in the absence of irqchip support Jan Kiszka
@ 2011-12-14 18:25 ` Jan Kiszka
2011-12-21 19:39 ` Marcelo Tosatti
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kiszka @ 2011-12-14 18:25 UTC (permalink / raw)
To: Avi Kivity, Marcelo Tosatti; +Cc: kvm
Move the test for KVM_PIT_FLAGS_HPET_LEGACY into create_pit_timer
instead of replicating it on the caller site.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
arch/x86/kvm/i8254.c | 10 +++-------
1 files changed, 3 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 405f262..d68f99d 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -344,7 +344,7 @@ static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
struct kvm_timer *pt = &ps->pit_timer;
s64 interval;
- if (!irqchip_in_kernel(kvm))
+ if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
return;
interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
@@ -397,15 +397,11 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val)
case 1:
/* FIXME: enhance mode 4 precision */
case 4:
- if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {
- create_pit_timer(kvm, val, 0);
- }
+ create_pit_timer(kvm, val, 0);
break;
case 2:
case 3:
- if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){
- create_pit_timer(kvm, val, 1);
- }
+ create_pit_timer(kvm, val, 1);
break;
default:
destroy_pit_timer(kvm->arch.vpit);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] KVM: x86: Consolidate PIT legacy test
2011-12-14 18:25 ` [PATCH 2/2] KVM: x86: Consolidate PIT legacy test Jan Kiszka
@ 2011-12-21 19:39 ` Marcelo Tosatti
0 siblings, 0 replies; 3+ messages in thread
From: Marcelo Tosatti @ 2011-12-21 19:39 UTC (permalink / raw)
To: Jan Kiszka; +Cc: Avi Kivity, kvm
On Wed, Dec 14, 2011 at 07:25:33PM +0100, Jan Kiszka wrote:
> Move the test for KVM_PIT_FLAGS_HPET_LEGACY into create_pit_timer
> instead of replicating it on the caller site.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> arch/x86/kvm/i8254.c | 10 +++-------
> 1 files changed, 3 insertions(+), 7 deletions(-)
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-12-21 20:23 UTC | newest]
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2011-12-14 18:25 [PATCH 1/2] KVM: x86: Prevent starting PIT timers in the absence of irqchip support Jan Kiszka
2011-12-14 18:25 ` [PATCH 2/2] KVM: x86: Consolidate PIT legacy test Jan Kiszka
2011-12-21 19:39 ` Marcelo Tosatti
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