| Message ID | 20231016165616.33442-1-nsaenz@amazon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] KVM: x86: hyper-v: Don't auto-enable stimer during deserialization | expand |
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 7c2dac6824e2..238afd7335e4 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -727,10 +727,12 @@ static int stimer_set_count(struct kvm_vcpu_hv_stimer *stimer, u64 count, stimer_cleanup(stimer); stimer->count = count; - if (stimer->count == 0) - stimer->config.enable = 0; - else if (stimer->config.auto_enable) - stimer->config.enable = 1; + if (!host) { + if (stimer->count == 0) + stimer->config.enable = 0; + else if (stimer->config.auto_enable) + stimer->config.enable = 1; + } if (stimer->config.enable) stimer_mark_pending(stimer, false);
By not honoring the 'stimer->config.enable' state during stimer deserialization we might introduce spurious timer interrupts. For example through the following events: - The stimer is configured in auto-enable mode. - The stimer's count is set and the timer enabled. - The stimer expires, an interrupt is injected. - We live migrate the VM. - The stimer config and count are deserialized, auto-enable is ON, the stimer is re-enabled. - The stimer expires right away, and injects an unwarranted interrupt. So let's not change the stimer's enable state if the MSR write comes from user-space. Fixes: 1f4b34f825e8 ("kvm/x86: Hyper-V SynIC timers") Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com> --- Changes since v1: - Cover all 'stimer->config.enable' updates. arch/x86/kvm/hyperv.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)