From 4467c6c118b85133846785f517e5733112e811b4 Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Mon, 22 Feb 2016 12:13:02 +0300 Subject: [PATCH] hyperv: cpu hotplug fix with HyperV enabled MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 check 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 Färber" Reviewed-by: Eduardo Habkost Signed-off-by: Eduardo Habkost --- target-i386/kvm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 7974acb399f..08d64447413 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 |= HV_X64_GUEST_CRASH_MSR_AVAILABLE; } + c->edx |= HV_X64_CPU_DYNAMIC_PARTITIONING_AVAILABLE; if (cpu->hyperv_reset && has_msr_hv_reset) { c->eax |= HV_X64_MSR_RESET_AVAILABLE; } -- 2.39.5