From 99b48ecc8e800983b6e00a2350daaeceba1f7406 Mon Sep 17 00:00:00 2001 From: Jon Doron Date: Fri, 17 Jul 2020 15:52:38 +0300 Subject: [PATCH] x86/kvm/hyper-v: Synic default SCONTROL MSR needs to be enabled Based on an analysis of the HyperV firmwares (Gen1 and Gen2) it seems like the SCONTROL is not being set to the ENABLED state as like we have thought. Also from a test done by Vitaly Kuznetsov, running a nested HyperV it was concluded that the first access to the SCONTROL MSR with a read resulted with the value of 0x1, aka HV_SYNIC_CONTROL_ENABLE. It's important to note that this diverges from the value states in the HyperV TLFS of 0. Signed-off-by: Jon Doron Message-Id: <20200717125238.1103096-2-arilou@gmail.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/hyperv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index af9cdb4..814d3ae 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -900,6 +900,7 @@ int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages) kvm_request_apicv_update(vcpu->kvm, false, APICV_INHIBIT_REASON_HYPERV); synic->active = true; synic->dont_zero_synic_pages = dont_zero_synic_pages; + synic->control = HV_SYNIC_CONTROL_ENABLE; return 0; } -- 2.7.4