From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Gaoning Pan <pgn@zju.edu.cn>, Yongkang Jia <kangel@zju.edu.cn>
Subject: Re: [PATCH 2/4] KVM: nVMX: Defer APICv updates while L2 is active until L1 is active
Date: Tue, 19 Apr 2022 15:57:00 +0000 [thread overview]
Message-ID: <Yl7bzNi9HjbgIAQ5@google.com> (raw)
In-Reply-To: <8b2ff3dc317db18c8128381d5d62057a90f68265.camel@redhat.com>
On Tue, Apr 19, 2022, Maxim Levitsky wrote:
> On Mon, 2022-04-18 at 15:35 +0000, Sean Christopherson wrote:
> > On Mon, Apr 18, 2022, Maxim Levitsky wrote:
> > > On Sat, 2022-04-16 at 03:42 +0000, Sean Christopherson wrote:
> > > When L2 uses APICv/AVIC, we just safely passthrough its usage to the real hardware.
> > >
> > > If we were to to need to inhibit it, we would have to emulate APICv/AVIC so that L1 would
> > > still think that it can use it - thankfully there is no need for that.
> >
> > What if L1 passes through IRQs and all MSRs to L2?
...
> - vmcs02 can't have APICv enabled, because passthrough of interrupts thankfully
> conflicts with APICv (virtual interrupt delivery depends on intercepting interrupts)
> and even if that was false, it would have contained L2's APICv settings which should
> continue to work as usual.
Ah, this was the critical piece I was forgetting. I'll tweak the changelog and
post a new version.
Thanks!
next prev parent reply other threads:[~2022-04-19 15:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-16 3:42 [PATCH 0/4] KVM: x86: APICv fixes Sean Christopherson
2022-04-16 3:42 ` [PATCH 1/4] KVM: x86: Tag APICv DISABLE inhibit, not ABSENT, if APICv is disabled Sean Christopherson
2022-04-18 8:37 ` Maxim Levitsky
2022-04-16 3:42 ` [PATCH 2/4] KVM: nVMX: Defer APICv updates while L2 is active until L1 is active Sean Christopherson
2022-04-18 12:49 ` Maxim Levitsky
2022-04-18 15:35 ` Sean Christopherson
2022-04-19 6:44 ` Maxim Levitsky
2022-04-19 15:57 ` Sean Christopherson [this message]
2022-04-16 3:42 ` [PATCH 3/4] KVM: x86: Pend KVM_REQ_APICV_UPDATE during vCPU creation to fix a race Sean Christopherson
2022-04-18 12:49 ` Maxim Levitsky
2022-04-16 3:42 ` [PATCH 4/4] KVM: x86: Skip KVM_GUESTDBG_BLOCKIRQ APICv update if APICv is disabled Sean Christopherson
2022-04-18 12:50 ` Maxim Levitsky
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