From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Cathy Avery <cavery@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
vkuznets@redhat.com, wei.huang2@amd.com
Subject: Re: [PATCH 2/2] KVM: x86: check_nested_events if there is an injectable NMI
Date: Thu, 23 Apr 2020 20:32:32 +0200 [thread overview]
Message-ID: <119b9a64-b071-41e3-f690-89f4ac52bd7b@redhat.com> (raw)
In-Reply-To: <793bf6ba-a21a-02cc-c80a-05a7af37b5b6@redhat.com>
On 23/04/20 17:43, Paolo Bonzini wrote:
>>
> Ah no, it's a bug in Cathy's patch and it's a weird one.
>
> The problem is that on AMD you exit guest mode with the NMI latched and
> GIF=0. So check_nested_events should enable the NMI window in addition
> to causing a vmexit.
>
> So why does it work? Because on AMD we don't have (yet)
> nested_run_pending, so we just check if we already have a vmexit
> scheduled and if so return -EBUSY. The second call causes
> inject_pending_event to return -EBUSY and thus go through KVM_REQ_EVENT
> again, which enables the NMI window.
... and this means that suddenly your event handling series has become
twice as large so I'm taking it over.
Paolo
next prev parent reply other threads:[~2020-04-23 18:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 20:11 [PATCH 0/2] KVM: SVM: Implement check_nested_events for NMI Cathy Avery
2020-04-14 20:11 ` [PATCH 1/2] " Cathy Avery
2020-04-14 20:11 ` [PATCH 2/2] KVM: x86: check_nested_events if there is an injectable NMI Cathy Avery
2020-04-23 14:42 ` Sean Christopherson
2020-04-23 15:10 ` Paolo Bonzini
2020-04-23 15:35 ` Sean Christopherson
2020-04-23 15:43 ` Paolo Bonzini
2020-04-23 18:32 ` Paolo Bonzini [this message]
2020-04-23 15:36 ` Cathy Avery
2020-04-23 15:45 ` Paolo Bonzini
2020-04-23 18:33 ` Sean Christopherson
2020-04-23 18:47 ` Paolo Bonzini
2020-04-15 9:49 ` [PATCH 0/2] KVM: SVM: Implement check_nested_events for NMI Vitaly Kuznetsov
2020-04-15 12:45 ` Paolo Bonzini
2020-04-23 13:43 ` Paolo Bonzini
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