Messages in this thread Patch in this message | | | From | Avi Kivity <> | Subject | [PATCH 10/11] KVM: Fix local apic timer divide by zero | Date | Sun, 21 Oct 2007 13:08:11 +0200 |
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From: Kevin Pedretti <kevin.pedretti@gmail.com>
kvm_lapic_reset() was initializing apic->timer.divide_count to 0, which could potentially lead to a divide by zero error in apic_get_tmcct(). Any guest that reads the APIC's CCR (current count) register before setting DCR (divide configuration) would trigger a divide by zero exception in the host kernel, leading to a host-OS crash.
This patch results in apic->timer.divide_count being initialized to 2 at reset, eliminating the bug (DCR=0 at reset, meaning divide by 2).
Signed-off-by: Kevin Pedretti <kevin.pedretti@gmail.com> Signed-off-by: Avi Kivity <avi@qumranet.com> --- drivers/kvm/lapic.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c index a190587..443730e 100644 --- a/drivers/kvm/lapic.c +++ b/drivers/kvm/lapic.c @@ -853,7 +853,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu) apic_set_reg(apic, APIC_ISR + 0x10 * i, 0); apic_set_reg(apic, APIC_TMR + 0x10 * i, 0); } - apic->timer.divide_count = 0; + update_divide_count(apic); atomic_set(&apic->timer.pending, 0); if (vcpu->vcpu_id == 0) vcpu->apic_base |= MSR_IA32_APICBASE_BSP; -- 1.5.3 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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