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From: Paolo Bonzini <pbonzini@redhat.com>
To: Liran Alon <liran.alon@oracle.com>
Cc: rkrcmar@redhat.com, kvm@vger.kernel.org,
	sean.j.christopherson@intel.com, jmattson@google.com,
	vkuznets@redhat.com, Joao Martins <joao.m.martins@oracle.com>
Subject: Re: [PATCH 2/2] KVM: nVMX: Update vmcs01 TPR_THRESHOLD if L2 changed L1 TPR
Date: Mon, 11 Nov 2019 16:59:36 +0100	[thread overview]
Message-ID: <58163b3f-d4ac-6091-a0f8-7e987c224118@redhat.com> (raw)
In-Reply-To: <6CAEE592-02B0-4E25-B2D2-20E5B55A5D19@oracle.com>

On 11/11/19 16:24, Liran Alon wrote:
> Because when L1 don’t use TPR-Shadow, L0 configures vmcs02 without TPR-Shadow.
> Thus, writing to vmcs02->tpr_threshold doesn’t have any effect.

Uh, sorry that was obvious:

 	if (exec_control & CPU_BASED_TPR_SHADOW)
 		vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold);

Paolo

> If l1 do use TPR-Shadow, then VMX’s update_cr8_intercept() doesn’t write to vmcs at all,
> because it means L1 defines a vTPR for L2 and thus doesn’t provide it direct access to L1 TPR.


  reply	other threads:[~2019-11-11 15:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-11 12:30 [PATCH 0/2] KVM: nVMX: Update vmcs01 TPR_THRESHOLD if L2 changed L1 TPR Liran Alon
2019-11-11 12:30 ` [PATCH 1/2] KVM: VMX: Refactor update_cr8_intercept() Liran Alon
2019-11-11 14:57   ` Paolo Bonzini
2019-11-11 15:00     ` Liran Alon
2019-11-11 16:01       ` Paolo Bonzini
2019-11-11 16:02         ` Liran Alon
2019-11-11 12:30 ` [PATCH 2/2] KVM: nVMX: Update vmcs01 TPR_THRESHOLD if L2 changed L1 TPR Liran Alon
2019-11-11 15:02   ` Paolo Bonzini
2019-11-11 15:24     ` Liran Alon
2019-11-11 15:59       ` Paolo Bonzini [this message]
2019-11-11 16:07       ` Paolo Bonzini
2019-11-11 16:17         ` Liran Alon
2019-11-11 16:50           ` Paolo Bonzini

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