From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, qemu-devel@nongnu.org
Cc: Eduardo Habkost <ehabkost@redhat.com>,
Richard Henderson <rth@twiddle.net>,
Marcelo Tosatti <mtosatti@redhat.com>,
Liran Alon <liran.alon@oracle.com>,
Roman Kagan <rkagan@virtuozzo.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH RFC] target/i386: filter out VMX_PIN_BASED_POSTED_INTR when enabling SynIC
Date: Tue, 18 Feb 2020 18:47:40 +0100 [thread overview]
Message-ID: <d5a3159d-4cab-ef94-bbfc-e9120324cd3e@redhat.com> (raw)
In-Reply-To: <87k14j962l.fsf@vitty.brq.redhat.com>
On 18/02/20 18:08, Vitaly Kuznetsov wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
>
>> On 18/02/20 15:44, Vitaly Kuznetsov wrote:
>>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>>> ---
>>> RFC: This is somewhat similar to eVMCS breakage and it is likely possible
>>> to fix this in KVM. I decided to try QEMU first as this is a single
>>> control and unlike eVMCS we don't need to keep a list of things to disable.
>>
>> I think you should disable "virtual-interrupt delivery" instead (which
>> in turn requires "process posted interrupts" to be zero). That is the
>> one that is incompatible with AutoEOI interrupts.
>
> I'm fighting the symptoms, not the cause :-) My understanding is that
> when SynIC is enabled for CPU0 KVM does
>
> kvm_vcpu_update_apicv()
> vmx_refresh_apicv_exec_ctrl()
> pin_controls_set()
>
> for *all* vCPUs (KVM_REQ_APICV_UPDATE). I'm not sure why
> SECONDARY_EXEC_APIC_REGISTER_VIRT/SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY
> are not causing problems and only PIN_BASED_POSTED_INTR does as we clear
> them all (not very important atm).
Let's take a step back, what is the symptom, i.e. how does it fail?
Because thinking more about it, since we have separate VMCS we can set
PIN_BASED_POSTED_INTR and SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY just fine
in the vmcs02. The important part is to unconditionally call
vmx_deliver_nested_posted_interrupt.
Something like
if (kvm_x86_ops->deliver_posted_interrupt(vcpu, vector)) {
kvm_lapic_set_irr(vector, apic);
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
}
and in vmx_deliver_posted_interrupt
r = vmx_deliver_nested_posted_interrupt(vcpu, vector);
if (!r)
return 0;
if (!vcpu->arch.apicv_active)
return -1;
...
return 0;
Paolo
next prev parent reply other threads:[~2020-02-18 17:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 14:44 [PATCH RFC] target/i386: filter out VMX_PIN_BASED_POSTED_INTR when enabling SynIC Vitaly Kuznetsov
2020-02-18 16:13 ` Paolo Bonzini
2020-02-18 17:08 ` Vitaly Kuznetsov
2020-02-18 17:47 ` Paolo Bonzini [this message]
2020-02-19 9:54 ` Vitaly Kuznetsov
2020-02-18 16:56 ` no-reply
2020-02-18 17:14 ` Vitaly Kuznetsov
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