From: Igor Mammedov <imammedo@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN
Date: Mon, 3 Jan 2022 10:40:57 +0100 [thread overview]
Message-ID: <20220103104057.4dcf7948@redhat.com> (raw)
In-Reply-To: <87mtkdqm7m.fsf@redhat.com>
On Mon, 03 Jan 2022 09:04:29 +0100
Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
>
> > On 12/27/21 18:32, Igor Mammedov wrote:
> >>> Tweaked and queued nevertheless, thanks.
> >> it seems this patch breaks VCPU hotplug, in scenario:
> >>
> >> 1. hotunplug existing VCPU (QEMU stores VCPU file descriptor in parked cpus list)
> >> 2. hotplug it again (unsuspecting QEMU reuses stored file descriptor when recreating VCPU)
> >>
> >> RHBZ:https://bugzilla.redhat.com/show_bug.cgi?id=2028337#c11
> >>
> >
> > The fix here would be (in QEMU) to not call KVM_SET_CPUID2 again.
> > However, we need to work around it in KVM, and allow KVM_SET_CPUID2 if
> > the data passed to the ioctl is the same that was set before.
>
> Are we sure the data is going to be *exactly* the same? In particular,
> when using vCPU fds from the parked list, do we keep the same
> APIC/x2APIC id when hotplugging? Or can we actually hotplug with a
> different id?
If I recall it right, it can be a different ID easily.
next prev parent reply other threads:[~2022-01-03 9:41 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 17:58 [PATCH 0/2] KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN Vitaly Kuznetsov
2021-11-22 17:58 ` [PATCH 1/2] KVM: selftests: Avoid KVM_SET_CPUID2 after KVM_RUN in hyperv_features test Vitaly Kuznetsov
2021-11-22 17:58 ` [PATCH 2/2] KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN Vitaly Kuznetsov
2021-11-26 12:20 ` Paolo Bonzini
2021-12-27 17:32 ` Igor Mammedov
2022-01-02 17:31 ` Paolo Bonzini
2022-01-03 8:04 ` Vitaly Kuznetsov
2022-01-03 9:40 ` Igor Mammedov [this message]
2022-01-03 12:56 ` Vitaly Kuznetsov
2022-01-05 8:17 ` Igor Mammedov
2022-01-05 9:12 ` Vitaly Kuznetsov
2022-01-05 9:10 ` Paolo Bonzini
2022-01-05 10:09 ` Vitaly Kuznetsov
2022-01-07 9:02 ` Vitaly Kuznetsov
2022-01-07 18:15 ` Paolo Bonzini
2022-01-11 8:00 ` Igor Mammedov
2022-01-12 13:58 ` Vitaly Kuznetsov
2022-01-12 18:39 ` Paolo Bonzini
2022-01-13 9:27 ` Vitaly Kuznetsov
2022-01-13 14:28 ` Maxim Levitsky
2022-01-13 14:36 ` Vitaly Kuznetsov
2022-01-13 14:41 ` Maxim Levitsky
2022-01-13 14:59 ` Vitaly Kuznetsov
2022-01-13 16:26 ` Sean Christopherson
2022-01-13 16:30 ` Maxim Levitsky
2022-01-13 22:33 ` Sean Christopherson
2022-01-14 8:28 ` Maxim Levitsky
2022-01-14 16:08 ` Sean Christopherson
2022-01-14 8:55 ` Igor Mammedov
2022-01-14 9:31 ` Vitaly Kuznetsov
2022-01-14 11:22 ` Igor Mammedov
2022-01-14 12:25 ` Vitaly Kuznetsov
2022-01-14 17:00 ` Sean Christopherson
2022-01-17 9:55 ` Vitaly Kuznetsov
2022-01-17 11:20 ` Paolo Bonzini
2022-01-17 13:02 ` Vitaly Kuznetsov
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