Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b33ac88b4c23330043acad930517282eb486db1d
Commit: b33ac88b4c23330043acad930517282eb486db1d
Parent: 0552f73b9a81d39d50b71a5c06cf36efff80b6fd
Author: Kevin Pedretti <[EMAIL PROTECTED]>
AuthorDate: Sun Oct 21 08:54:53 2007 +0200
Committer: Avi Kivity <[EMAIL PROTECTED]>
CommitDate: Mon Oct 22 12:03:29 2007 +0200
KVM: Fix local apic timer divide by zero
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 <[EMAIL PROTECTED]>
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
---
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;
-
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