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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-03-28 23:41:51 +0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-04-04 19:17:24 +0400 |
| commit | 4009b2499eee26c7f413073300d124a37765dfca (patch) | |
| tree | 05b431aec59a1d17fbbd9d29c46fd1e51831e260 /virt/kvm | |
| parent | 5678de3f15010b9022ee45673f33bcfc71d47b60 (diff) | |
| download | linux-4009b2499eee26c7f413073300d124a37765dfca.tar.xz | |
KVM: ioapic: try to recover if pending_eoi goes out of range
The RTC tracking code tracks the cardinality of rtc_status.dest_map
into rtc_status.pending_eoi. It has some WARN_ONs that trigger if
pending_eoi ever becomes negative; however, these do not do anything
to recover, and it bad things will happen soon after they trigger.
When the next RTC interrupt is triggered, rtc_check_coalesced() will
return false, but ioapic_service will find pending_eoi != 0 and
do a BUG_ON. To avoid this, should pending_eoi ever be nonzero,
call kvm_rtc_eoi_tracking_restore_all to recompute a correct
dest_map and pending_eoi.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/ioapic.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index d98d107efb05..2458a1dc2ba9 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -97,6 +97,14 @@ static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic) bitmap_zero(ioapic->rtc_status.dest_map, KVM_MAX_VCPUS); } +static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic); + +static void rtc_status_pending_eoi_check_valid(struct kvm_ioapic *ioapic) +{ + if (WARN_ON(ioapic->rtc_status.pending_eoi < 0)) + kvm_rtc_eoi_tracking_restore_all(ioapic); +} + static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu) { bool new_val, old_val; @@ -120,9 +128,8 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu) } else { __clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map); ioapic->rtc_status.pending_eoi--; + rtc_status_pending_eoi_check_valid(ioapic); } - - WARN_ON(ioapic->rtc_status.pending_eoi < 0); } void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu) @@ -149,10 +156,10 @@ static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic) static void rtc_irq_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu) { - if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map)) + if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map)) { --ioapic->rtc_status.pending_eoi; - - WARN_ON(ioapic->rtc_status.pending_eoi < 0); + rtc_status_pending_eoi_check_valid(ioapic); + } } static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic) @@ -353,6 +360,12 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status) ioapic->irr &= ~(1 << irq); if (irq == RTC_GSI && line_status) { + /* + * pending_eoi cannot ever become negative (see + * rtc_status_pending_eoi_check_valid) and the caller + * ensures that it is only called if it is >= zero, namely + * if rtc_irq_check_coalesced returns false). + */ BUG_ON(ioapic->rtc_status.pending_eoi != 0); ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, ioapic->rtc_status.dest_map); |