On 4/12/2024 3:07 AM, Sean Christopherson wrote:
> On Fri, Jan 26, 2024, Xiong Zhang wrote:
>> From: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>
>>
>> Add function to register/unregister PMI handler at KVM module
>> initialization and destroy time. This allows the host PMU with passthough
>> capability enabled switch PMI handler at PMU context switch time.
>>
>> Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>
>> Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/x86.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 2c924075f6f1..4432e736129f 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -10611,6 +10611,18 @@ void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu)
>> }
>> EXPORT_SYMBOL_GPL(__kvm_request_immediate_exit);
>>
>> +void kvm_passthrough_pmu_handler(void)
>
> s/pmu/pmi, and this needs a verb. Maybe kvm_handle_guest_pmi()? Definitely
> open to other names.
kvm_handle_guest_pmi() is ok.
>
>> +{
>> + struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>> +
>> + if (!vcpu) {
>> + pr_warn_once("%s: no running vcpu found!\n", __func__);
>
> Unless I misunderstand the code, this can/should be a full WARN_ON_ONCE. If a
> PMI skids all the way past vcpu_put(), we've got big problems.
yes, it is big problems and user should be noticed.
>
>> + return;
>> + }
>> +
>> + kvm_make_request(KVM_REQ_PMI, vcpu);
>> +}
>> +
>> /*
>> * Called within kvm->srcu read side.
>> * Returns 1 to let vcpu_run() continue the guest execution loop without
>> @@ -13815,6 +13827,7 @@ static int __init kvm_x86_init(void)
>> {
>> kvm_mmu_x86_module_init();
>> mitigate_smt_rsb &= boot_cpu_has_bug(X86_BUG_SMT_RSB) && cpu_smt_possible();
>> + kvm_set_vpmu_handler(kvm_passthrough_pmu_handler);
>
> Hmm, a few patches late, but the "kvm" scope is weird. This calls a core x86
> function, not a KVM function.
>
> And to reduce exports and copy+paste, what about something like this?
>
> void x86_set_kvm_irq_handler(u8 vector, void (*handler)(void))
> {
> if (!handler)
> handler = dummy_handler;
>
> if (vector == POSTED_INTR_WAKEUP_VECTOR)
> kvm_posted_intr_wakeup_handler = handler;
> else if (vector == KVM_GUEST_PMI_VECTOR)
> kvm_guest_pmi_handler = handler;
> else
> WARN_ON_ONCE(1);
>
> if (handler == dummy_handler)
> synchronize_rcu();
> }
> EXPORT_SYMBOL_GPL(x86_set_kvm_irq_handler);
Good suggestion. Follow it in next version.
