From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38167) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1pFL-0008EH-Iq for qemu-devel@nongnu.org; Tue, 23 Jul 2013 22:56:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V1pFK-0004oe-Kr for qemu-devel@nongnu.org; Tue, 23 Jul 2013 22:56:11 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:20206) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1pFI-0004nK-Vw for qemu-devel@nongnu.org; Tue, 23 Jul 2013 22:56:10 -0400 Message-ID: <51EF4201.9040802@huawei.com> Date: Wed, 24 Jul 2013 10:54:57 +0800 From: "Peter Huang(Peng)" MIME-Version: 1.0 References: <51ED1668.7030205@huawei.com> <20130722134138.GE19826@otherpad.lan.raisama.net> <51EDEE20.4060206@huawei.com> <20130723112712.GF4718@orkuz.home> <51EF2469.1090402@huawei.com> In-Reply-To: <51EF2469.1090402@huawei.com> Content-Type: multipart/alternative; boundary="------------000104080503030705040204" Subject: [Qemu-devel] [Solved]FYI//Re: [Question] why x2apic's set by default without host support(on Nehalem CPU). List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost , libvir-list@redhat.com, qemu-devel@nongnu.org, Jiri Denemark --------------000104080503030705040204 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit FYI, just for information sharing. KVM emulated x2apic feature no matter host supports it or not. You can get the code from arch/x86/kvm/cpuid.c. kvm_dev_ioctl_get_supported_cpuid ()->do_cpuid_ent() /* we support x2apic emulation even if host does not support * it since we emulate x2apic in software */ entry->ecx |= F(*X2APIC*); QEMU will get this feature through kvm_ioctl(). On 2013-07-24 8:48, Peter Huang(Peng) wrote: > Hi,Jiri > > Thanks for replying. > > So why VM identified different features from host is due to the hypervisor filtering. > I will dig into the hypervisor of how it filter features, and update status later. > > Thanks again. --------------000104080503030705040204 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit FYI, just for information sharing.

KVM emulated x2apic feature no matter host supports it or not.
You can get the code from arch/x86/kvm/cpuid.c.
kvm_dev_ioctl_get_supported_cpuid ()->do_cpuid_ent()

  /* we support x2apic emulation even if host does not support

                 * it since we emulate x2apic in software */

                entry->ecx |= F(X2APIC);


QEMU will get this feature through kvm_ioctl().

On 2013-07-24 8:48, Peter Huang(Peng) wrote: 
Hi,Jiri

Thanks for replying.

So why VM identified different features from host is due to the hypervisor filtering.
I will dig into the hypervisor of how it filter features, and update status later.

Thanks again.
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