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From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org, Alex Williamson <alex.williamson@redhat.com>,
	Pei Zhang <pezhang@redhat.com>
Subject: Re: [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device
Date: Wed, 12 May 2021 11:34:57 -0400	[thread overview]
Message-ID: <YJv1ofNKDpRF+vtu@t490s> (raw)
In-Reply-To: <YJvpNHAILLTghW1L@google.com>

On Wed, May 12, 2021 at 02:41:56PM +0000, Sean Christopherson wrote:
> On Tue, May 11, 2021, Marcelo Tosatti wrote:
> > > The KVM_REQ_UNBLOCK patch will resume execution even any such event
> > 
> > 						  even without any such event
> > 
> > > occuring. So the behaviour would be different from baremetal.
> 
> I agree with Marcelo, we don't want to spuriously unhalt the vCPU.  It's legal,
> albeit risky, to do something like
> 
> 	hlt
> 	/* #UD to triple fault if this CPU is awakened. */
> 	ud2
> 
> when offlining a CPU, in which case the spurious wake event will crash the guest.

We can avoid that by moving the check+clear of KVM_REQ_UNBLOCK from
kvm_vcpu_has_events() into kvm_vcpu_check_block() as replied in the other
thread.  But I also agree Marcelo's series should work already to fix the bug,
hence no strong opinion on this.

Thanks,

-- 
Peter Xu


  reply	other threads:[~2021-05-12 15:39 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-07 13:06 [patch 0/4] VMX: configure posted interrupt " Marcelo Tosatti
2021-05-07 13:06 ` [patch 1/4] KVM: x86: add start_assignment hook to kvm_x86_ops Marcelo Tosatti
2021-05-07 19:16   ` Peter Xu
2021-05-10 17:53     ` Marcelo Tosatti
2021-05-07 13:06 ` [patch 2/4] KVM: add arch specific vcpu_check_block callback Marcelo Tosatti
2021-05-07 13:06 ` [patch 3/4] KVM: x86: implement kvm_arch_vcpu_check_block callback Marcelo Tosatti
2021-05-07 13:06 ` [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device Marcelo Tosatti
2021-05-07 17:22   ` Sean Christopherson
2021-05-07 19:29     ` Peter Xu
2021-05-07 22:08       ` Marcelo Tosatti
2021-05-11 14:39         ` Peter Xu
2021-05-11 14:51           ` Marcelo Tosatti
2021-05-11 16:19             ` Peter Xu
2021-05-11 17:18               ` Marcelo Tosatti
2021-05-11 21:35                 ` Peter Xu
2021-05-11 23:51                   ` Marcelo Tosatti
2021-05-12  0:02                     ` Marcelo Tosatti
2021-05-12  0:38                       ` Peter Xu
2021-05-12 11:10                         ` Marcelo Tosatti
2021-05-12 14:41                       ` Sean Christopherson
2021-05-12 15:34                         ` Peter Xu [this message]
2021-05-10 17:26 [patch 0/4] VMX: configure posted interrupt descriptor when assigning device (v3) Marcelo Tosatti
2021-05-10 17:26 ` [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device Marcelo Tosatti
2021-05-24 15:55   ` Paolo Bonzini
2021-05-24 17:53     ` Marcelo Tosatti
2021-05-25 11:58       ` Paolo Bonzini
2021-05-11 23:57 [patch 0/4] VMX: configure posted interrupt descriptor when assigning device (v4) Marcelo Tosatti
2021-05-11 23:57 ` [patch 4/4] KVM: VMX: update vcpu posted-interrupt descriptor when assigning device Marcelo Tosatti

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