70 lines
2.2 KiB
Diff
70 lines
2.2 KiB
Diff
From 0924ab2cfa98b1ece26c033d696651fd62896c69 Mon Sep 17 00:00:00 2001
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From: Jan Kiszka <jan.kiszka@siemens.com>
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Date: Wed, 14 Dec 2011 19:25:13 +0100
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Subject: [PATCH] KVM: x86: Prevent starting PIT timers in the absence of
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irqchip support
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User space may create the PIT and forgets about setting up the irqchips.
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In that case, firing PIT IRQs will crash the host:
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BUG: unable to handle kernel NULL pointer dereference at 0000000000000128
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IP: [<ffffffffa10f6280>] kvm_set_irq+0x30/0x170 [kvm]
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...
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Call Trace:
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[<ffffffffa11228c1>] pit_do_work+0x51/0xd0 [kvm]
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[<ffffffff81071431>] process_one_work+0x111/0x4d0
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[<ffffffff81071bb2>] worker_thread+0x152/0x340
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[<ffffffff81075c8e>] kthread+0x7e/0x90
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[<ffffffff815a4474>] kernel_thread_helper+0x4/0x10
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Prevent this by checking the irqchip mode before starting a timer. We
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can't deny creating the PIT if the irqchips aren't set up yet as
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current user land expects this order to work.
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Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
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Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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---
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arch/x86/kvm/i8254.c | 10 +++++++---
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1 files changed, 7 insertions(+), 3 deletions(-)
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diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
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index 76e3f1c..405f262 100644
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--- a/arch/x86/kvm/i8254.c
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+++ b/arch/x86/kvm/i8254.c
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@@ -338,11 +338,15 @@ static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
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return HRTIMER_NORESTART;
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}
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-static void create_pit_timer(struct kvm_kpit_state *ps, u32 val, int is_period)
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+static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
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{
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+ struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
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struct kvm_timer *pt = &ps->pit_timer;
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s64 interval;
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+ if (!irqchip_in_kernel(kvm))
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+ return;
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+
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interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
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pr_debug("create pit timer, interval is %llu nsec\n", interval);
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@@ -394,13 +398,13 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val)
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/* FIXME: enhance mode 4 precision */
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case 4:
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if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {
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- create_pit_timer(ps, val, 0);
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+ create_pit_timer(kvm, val, 0);
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}
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break;
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case 2:
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case 3:
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if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){
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- create_pit_timer(ps, val, 1);
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+ create_pit_timer(kvm, val, 1);
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}
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break;
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default:
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--
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1.7.6.2
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