From a4888486c5d755118a3c8a30416d7e0febdfb298 Mon Sep 17 00:00:00 2001 From: "Jan H. Schönherr" Date: Wed, 25 Oct 2017 16:43:26 +0200 Subject: KVM: VMX: Do not fully reset PI descriptor on vCPU reset MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Parts of the posted interrupt descriptor configure host behavior, such as the notification vector and destination. Overwriting them with zero as done during vCPU reset breaks posted interrupts. KVM (re-)writes these fields on certain occasions and belatedly fixes the situation in many cases. However, if you have a guest configured with "idle=poll", for example, the fields might stay zero forever. Do not reset the full descriptor in vmx_vcpu_reset(). Instead, reset only the outstanding notifications and leave everything else untouched. Signed-off-by: Jan H. Schönherr Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 95a01609d7ee..e0b4b64f211a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5619,8 +5619,10 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); - if (kvm_vcpu_apicv_active(vcpu)) - memset(&vmx->pi_desc, 0, sizeof(struct pi_desc)); + if (kvm_vcpu_apicv_active(vcpu)) { + pi_clear_on(&vmx->pi_desc); + memset(vmx->pi_desc.pir, 0, sizeof(vmx->pi_desc.pir)); + } if (vmx->vpid != 0) vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid); -- cgit v1.2.3-59-g8ed1b