From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49096) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXmYS-0006F9-8T for qemu-devel@nongnu.org; Mon, 22 Feb 2016 04:13:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aXmYP-0005Me-1l for qemu-devel@nongnu.org; Mon, 22 Feb 2016 04:13:20 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:44399 helo=relay.sw.ru) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aXmYO-0005Le-M1 for qemu-devel@nongnu.org; Mon, 22 Feb 2016 04:13:16 -0500 From: "Denis V. Lunev" Date: Mon, 22 Feb 2016 12:13:02 +0300 Message-Id: <1456132382-25327-1-git-send-email-den@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v3 1/1] hyperv: cpu hotplug fix with HyperV enabled List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , qemu-devel@nongnu.org, Paolo Bonzini , "Denis V. Lunev" , =?UTF-8?q?Andreas=20F=C3=A4rber?= , Richard Henderson With Hyper-V enabled CPU hotplug stops working. The CPU appears in device manager on Windows but does not appear in peformance monitor and control panel. The root of the problem is the following. Windows checks HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE bit in CPUID. The presence of this bit is enough to cure the situation. The bit should be set when CPU hotplug is allowed for HyperV VM. The chec= k that hot_add_cpu callback is defined is enough from the protocol point of view. Though this callback is defined almost always thus there is no need to export that knowledge in the other way. Signed-off-by: Denis V. Lunev Reviewed-by: Roman Kagan CC: Paolo Bonzini CC: Richard Henderson CC: Eduardo Habkost CC: "Andreas F=C3=A4rber" --- Changes from v2: - bit set unconditionally upon the discussion Changes from v1: - dropped command line option and set the bit if HyperV is enabled and hot_add_cpu callback is present target-i386/kvm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 7974acb..08d6444 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -639,6 +639,7 @@ int kvm_arch_init_vcpu(CPUState *cs) if (cpu->hyperv_crash && has_msr_hv_crash) { c->edx |=3D HV_X64_GUEST_CRASH_MSR_AVAILABLE; } + c->edx |=3D HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE; if (cpu->hyperv_reset && has_msr_hv_reset) { c->eax |=3D HV_X64_MSR_RESET_AVAILABLE; } --=20 2.1.4