From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Kechen Lu <kechenl@nvidia.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/5] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use
Date: Tue, 25 May 2021 09:11:10 +0200 [thread overview]
Message-ID: <2b8d0e27-a893-b090-7ecd-df17eefdf6f1@redhat.com> (raw)
In-Reply-To: <87fsyb8h7s.fsf@vitty.brq.redhat.com>
On 25/05/21 08:23, Vitaly Kuznetsov wrote:
>> Should it also disable APICv unconditionally if
>> HV_DEPRECATING_AEOI_RECOMMENDED is not in the guest CPUID? That should
>> avoid ping-pong between enabled and disabled APICv even in pathological
>> cases that we cannot think about.
> When you run Hyper-V on KVM it doesn't use SynIC (let alone AutoEOI) but
> we still inhibit APICv unconditionally. The patch as-is improves this
> without any userspace changes required and I see it as a benefit. Going
> forward, we will definitely add something like 'hv-synic-noaeoi' to QEMU
> to make non-nesting setups benefit too but it'll take a while for this
> option to propagate to real world configurations (sigh).
Ok, if enable<->disable APICv becomes an issue we can also consider
disabling APICv forever if AutoEOI is ever used.
Paolo
next prev parent reply other threads:[~2021-05-25 7:11 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 14:43 [PATCH v2 0/5] KVM: x86: hyper-v: Conditionally allow SynIC with APICv/AVIC Vitaly Kuznetsov
2021-05-18 14:43 ` [PATCH v2 1/5] KVM: SVM: Drop unneeded CONFIG_X86_LOCAL_APIC check for AVIC Vitaly Kuznetsov
2021-05-18 19:57 ` Sean Christopherson
2021-05-26 9:54 ` Maxim Levitsky
2021-05-18 14:43 ` [PATCH v2 2/5] KVM: VMX: Drop unneeded CONFIG_X86_LOCAL_APIC check from cpu_has_vmx_posted_intr() Vitaly Kuznetsov
2021-05-18 19:57 ` Sean Christopherson
2021-05-26 9:54 ` Maxim Levitsky
2021-05-18 14:43 ` [PATCH v2 3/5] KVM: x86: Use common 'enable_apicv' variable for both APICv and AVIC Vitaly Kuznetsov
2021-05-18 20:39 ` Sean Christopherson
2021-05-19 7:58 ` Vitaly Kuznetsov
2021-05-24 16:18 ` Paolo Bonzini
2021-05-24 16:52 ` Sean Christopherson
2021-05-24 17:02 ` Paolo Bonzini
2021-05-26 9:56 ` Maxim Levitsky
2021-05-26 15:07 ` Sean Christopherson
2021-05-26 15:52 ` Maxim Levitsky
2021-05-27 11:39 ` Paolo Bonzini
2021-05-18 14:43 ` [PATCH v2 4/5] KVM: x86: Invert APICv/AVIC enablement check Vitaly Kuznetsov
2021-05-18 21:05 ` Sean Christopherson
2021-05-26 9:57 ` Maxim Levitsky
2021-05-26 10:40 ` Vitaly Kuznetsov
2021-05-26 11:11 ` Maxim Levitsky
2021-05-18 14:43 ` [PATCH v2 5/5] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Vitaly Kuznetsov
2021-05-24 16:21 ` Paolo Bonzini
2021-05-25 6:23 ` Vitaly Kuznetsov
2021-05-25 7:11 ` Paolo Bonzini [this message]
2021-05-26 10:02 ` Maxim Levitsky
2021-05-26 10:01 ` Maxim Levitsky
2021-05-26 9:54 ` [PATCH v2 0/5] KVM: x86: hyper-v: Conditionally allow SynIC with APICv/AVIC Maxim Levitsky
2021-05-27 8:35 ` Vitaly Kuznetsov
2021-05-27 15:49 ` Maxim Levitsky
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