From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v4] KVM: VMX: Enable MSR-BASED TPR shadow even if APICv is inactive Date: Fri, 23 Sep 2016 01:13:50 +0200 Message-ID: <20160922231350.GB7554@potion> References: <1474501405-8312-1-git-send-email-wanpeng.li@hotmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Wanpeng Li , Paolo Bonzini , Wincy Van , Yang Zhang To: Wanpeng Li Return-path: Content-Disposition: inline In-Reply-To: <1474501405-8312-1-git-send-email-wanpeng.li@hotmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 2016-09-22 07:43+0800, Wanpeng Li: > From: Wanpeng Li > > I observed that kvmvapic(to optimize flexpriority=N or AMD) is used > to boost TPR access when testing kvm-unit-test/eventinj.flat tpr case > on my haswell desktop (w/ flexpriority, w/o APICv). Commit (8d14695f9542 > x86, apicv: add virtual x2apic support) disable virtual x2apic mode > completely if w/o APICv, and the author also told me that windows guest > can't enter into x2apic mode when he developed the APICv feature several > years ago. However, it is not truth currently, Interrupt Remapping and > vIOMMU is added to qemu and the developers from Intel test windows 8 can > work in x2apic mode w/ Interrupt Remapping enabled recently. > > This patch enables TPR shadow for virtual x2apic mode to boost > windows guest in x2apic mode even if w/o APICv. > > Can pass the kvm-unit-test. > > Suggested-by: Radim Krčmář > Suggested-by: Wincy Van > Reviewed-by: Radim Krčmář > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: Wincy Van > Cc: Yang Zhang > Signed-off-by: Wanpeng Li > --- Applied to kvm/queue, thanks.