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From: Greg KH <gregkh@linuxfoundation.org>
To: Haozhong Zhang <haozhong.zhang@intel.com>
Cc: stable@vger.kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Ramamurthy, Venkatesh" <venkatesh.ramamurthy@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>
Subject: Re: [PATCH-for-4.13 1/2] KVM: VMX: do not change SN bit in vmx_update_pi_irte()
Date: Tue, 3 Oct 2017 10:53:33 +0200	[thread overview]
Message-ID: <20171003085333.GD15659@kroah.com> (raw)
In-Reply-To: <20170927032240.21406-2-haozhong.zhang@intel.com>

On Wed, Sep 27, 2017 at 11:22:39AM +0800, Haozhong Zhang wrote:
> commit dc91f2eb1a4021eb6705c15e474942f84ab9b211 upstream.
> 
> In kvm_vcpu_trigger_posted_interrupt() and pi_pre_block(), KVM
> assumes that PI notification events should not be suppressed when the
> target vCPU is not blocked.
> 
> vmx_update_pi_irte() sets the SN field before changing an interrupt
> from posting to remapping, but it does not check the vCPU mode.
> Therefore, the change of SN field may break above the assumption.
> Besides, I don't see reasons to suppress notification events here, so
> remove the changes of SN field to avoid race condition.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
> Reported-by: "Ramamurthy, Venkatesh" <venkatesh.ramamurthy@intel.com>
> Reported-by: Dan Williams <dan.j.williams@intel.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: 28b835d60fcc ("KVM: Update Posted-Interrupts Descriptor when vCPU is preempted")

Also applied to 4.9 and 4.4 stable trees, as that's what this patch
fixes.

thanks,

greg k-h

  reply	other threads:[~2017-10-03  8:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-27  3:22 [PATCH-for-4.13 0/2] VT-d PI: fix race condition Haozhong Zhang
2017-09-27  3:22 ` [PATCH-for-4.13 1/2] KVM: VMX: do not change SN bit in vmx_update_pi_irte() Haozhong Zhang
2017-10-03  8:53   ` Greg KH [this message]
2017-09-27  3:22 ` [PATCH-for-4.13 2/2] KVM: VMX: remove WARN_ON_ONCE in kvm_vcpu_trigger_posted_interrupt Haozhong Zhang
2017-10-03  8:54   ` Greg KH
2017-09-27  8:16 ` [PATCH-for-4.13 0/2] VT-d PI: fix race condition Paolo Bonzini
2017-09-27  8:23   ` Haozhong Zhang

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