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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2016-06-20 22:33:48 -0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-06-27 15:30:41 +0200 |
| commit | b606f189c7d5bf9b875bba168162fe05287880fe (patch) | |
| tree | 20a06328aec2cbd036406e0e701cd21324a5f9fc | |
| parent | 8d93c874ac899bfdf0ad3787baef684a0c878c2c (diff) | |
| download | linux-b606f189c7d5bf9b875bba168162fe05287880fe.tar.gz | |
KVM: LAPIC: cap __delay at lapic_timer_advance_ns
The host timer which emulates the guest LAPIC TSC deadline timer has its expiration diminished by lapic_timer_advance_ns nanoseconds. Therefore if, at wait_lapic_expire, a difference larger than lapic_timer_advance_ns is encountered, delay at most lapic_timer_advance_ns. This fixes a problem where the guest can cause the host to delay for large amounts of time. Reported-by: Alan Jenkins <alan.christopher.jenkins@gmail.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/lapic.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index bbb5b283ff63..a397200281c1 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1310,7 +1310,8 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu) /* __delay is delay_tsc whenever the hardware has TSC, thus always. */ if (guest_tsc < tsc_deadline) - __delay(tsc_deadline - guest_tsc); + __delay(min(tsc_deadline - guest_tsc, + nsec_to_cycles(vcpu, lapic_timer_advance_ns))); } static void start_apic_timer(struct kvm_lapic *apic) |