Messages in this thread | | | From | Wanpeng Li <> | Date | Mon, 13 Nov 2017 16:12:33 +0800 | Subject | Re: [PATCH v4 2/4] KVM: X86: Add paravirt remote TLB flush |
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2017-11-13 15:59 GMT+08:00 Peter Zijlstra <peterz@infradead.org>: > On Sun, Nov 12, 2017 at 04:33:24PM -0800, Wanpeng Li wrote: >> +static void kvm_flush_tlb_others(const struct cpumask *cpumask, >> + const struct flush_tlb_info *info) >> +{ >> + u8 state; >> + int cpu; >> + struct kvm_steal_time *src; >> + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); >> + >> + if (unlikely(!flushmask)) >> + return; >> + >> + cpumask_copy(flushmask, cpumask); >> + /* >> + * We have to call flush only on online vCPUs. And >> + * queue flush_on_enter for pre-empted vCPUs >> + */ >> + for_each_cpu(cpu, cpumask) { > > Should this not iterate flushmask? Its far too early to think, so I'm > not sure this is an actual problem, but it does seem weird.
Agreed, should be flushmask in next version. :)
Regards, Wanpeng Li
> >> + src = &per_cpu(steal_time, cpu); >> + state = READ_ONCE(src->preempted); >> + if ((state & KVM_VCPU_PREEMPTED)) { >> + if (try_cmpxchg(&src->preempted, &state, >> + state | KVM_VCPU_SHOULD_FLUSH)) >> + __cpumask_clear_cpu(cpu, flushmask); >> + } >> + } >> + >> + native_flush_tlb_others(flushmask, info); >> +}
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