From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Liran Alon <liran.alon@oracle.com>
Cc: kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] KVM: x86: vmx: throttle immediate exit through preemtion timer to assist buggy guests
Date: Mon, 01 Apr 2019 10:39:39 +0200 [thread overview]
Message-ID: <87v9zy15mc.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <32296de3-8ce0-c20a-5948-a7eef267a328@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 29/03/19 16:32, Liran Alon wrote:
>> Paolo I am not sure this is the case here. Please read my other
>> replies in this email thread.
>>
>> I think this is just a standard issue of a level-triggered interrupt
>> handler in L1 (Hyper-V) that performs EOI before it lowers the
>> irq-line. I don’t think vector 96 is even related to the issue at
>> hand here. This is why after it was already handled, the loop of
>> EXTERNAL_INTERRUPT happens on vector 80 and not vector 96.
>
> Hmm... Vitaly, what machine were you testing on---does it have APIC-v?
> If not, then you should have seen either an EOI for irq 96 or a TPR
> below threshold vmexit. However, if it has APIC-v then you wouldn't
> have seen any of this (you only see the EOI for irq 80 because it's
> level triggered) and Liran is probably right.
>
It does, however, the issue is reproducible with and without
it. Moreover, I think the second simultaneous IRQ is just a red herring;
Here is another trace (enable_apicv). Posting it non-stripped and hope
your eyes will catch something I'm missing:
[001] 513675.736316: kvm_exit: reason VMRESUME rip 0xfffff80002cae115 info 0 0
[001] 513675.736321: kvm_entry: vcpu 0
[001] 513675.736565: kvm_exit: reason EXTERNAL_INTERRUPT rip 0xfffff80362dcd26d info 0 800000ec
[001] 513675.736566: kvm_nested_vmexit: rip fffff80362dcd26d reason EXTERNAL_INTERRUPT info1 0 info2 0 int_info 800000ec int_info_err 0
[001] 513675.736568: kvm_entry: vcpu 0
[001] 513675.736650: kvm_exit: reason EPT_VIOLATION rip 0xfffff80362dcd230 info 182 0
[001] 513675.736651: kvm_nested_vmexit: rip fffff80362dcd230 reason EPT_VIOLATION info1 182 info2 0 int_info 0 int_info_err 0
[001] 513675.736651: kvm_page_fault: address 261200000 error_code 182
-> injecting
[008] 513675.737059: kvm_set_irq: gsi 23 level 1 source 0
[008] 513675.737061: kvm_msi_set_irq: dst 0 vec 80 (Fixed|physical|level)
[008] 513675.737062: kvm_apic_accept_irq: apicid 0 vec 80 (Fixed|edge)
[001] 513675.737233: kvm_nested_vmexit_inject: reason EXTERNAL_INTERRUPT info1 0 info2 0 int_info 80000050 int_info_err 0
[001] 513675.737239: kvm_entry: vcpu 0
[001] 513675.737243: kvm_exit: reason EOI_INDUCED rip 0xfffff80002c85e1a info 50 0
-> immediate EOI causing re-injection (even preemption timer is not
involved here).
[001] 513675.737244: kvm_eoi: apicid 0 vector 80
[001] 513675.737245: kvm_fpu: unload
[001] 513675.737246: kvm_userspace_exit: reason KVM_EXIT_IOAPIC_EOI (26)
[001] 513675.737256: kvm_set_irq: gsi 23 level 1 source 0
[001] 513675.737259: kvm_msi_set_irq: dst 0 vec 80 (Fixed|physical|level)
[001] 513675.737260: kvm_apic_accept_irq: apicid 0 vec 80 (Fixed|edge)
[001] 513675.737264: kvm_fpu: load
[001] 513675.737265: kvm_entry: vcpu 0
[001] 513675.737271: kvm_exit: reason VMRESUME rip 0xfffff80002cae115 info 0 0
[001] 513675.737278: kvm_entry: vcpu 0
[001] 513675.737282: kvm_exit: reason PREEMPTION_TIMER rip 0xfffff80362dcc2d0 info 0 0
[001] 513675.737283: kvm_nested_vmexit: rip fffff80362dcc2d0 reason PREEMPTION_TIMER info1 0 info2 0 int_info 0 int_info_err 0
[001] 513675.737285: kvm_nested_vmexit_inject: reason EXTERNAL_INTERRUPT info1 0 info2 0 int_info 80000050 int_info_err 0
[001] 513675.737289: kvm_entry: vcpu 0
[001] 513675.737293: kvm_exit: reason EOI_INDUCED rip 0xfffff80002c85e1a info 50 0
[001] 513675.737293: kvm_eoi: apicid 0 vector 80
[001] 513675.737294: kvm_fpu: unload
[001] 513675.737295: kvm_userspace_exit: reason KVM_EXIT_IOAPIC_EOI (26)
[001] 513675.737299: kvm_set_irq: gsi 23 level 1 source 0
[001] 513675.737299: kvm_msi_set_irq: dst 0 vec 80 (Fixed|physical|level)
[001] 513675.737300: kvm_apic_accept_irq: apicid 0 vec 80 (Fixed|edge)
[001] 513675.737302: kvm_fpu: load
[001] 513675.737303: kvm_entry: vcpu 0
[001] 513675.737307: kvm_exit: reason VMRESUME rip 0xfffff80002cae115 info 0 0
...
--
Vitaly
next prev parent reply other threads:[~2019-04-01 8:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-28 20:31 [PATCH RFC] KVM: x86: vmx: throttle immediate exit through preemtion timer to assist buggy guests Vitaly Kuznetsov
2019-03-29 2:00 ` Liran Alon
2019-03-29 9:14 ` Vitaly Kuznetsov
2019-03-29 12:09 ` Liran Alon
2019-03-29 14:18 ` Paolo Bonzini
2019-03-29 14:40 ` Vitaly Kuznetsov
2019-03-29 15:01 ` Paolo Bonzini
2019-03-29 15:14 ` Vitaly Kuznetsov
2019-03-29 15:32 ` Liran Alon
2019-03-29 17:14 ` Paolo Bonzini
2019-04-01 8:39 ` Vitaly Kuznetsov [this message]
2019-04-01 10:08 ` Liran Alon
2019-04-01 10:41 ` Vitaly Kuznetsov
2019-04-01 8:50 ` Vitaly Kuznetsov
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