From patchwork Fri Feb 9 13:01:33 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 10208945 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 59E3F602D8 for ; Fri, 9 Feb 2018 13:01:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4C70829845 for ; Fri, 9 Feb 2018 13:01:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4147629848; Fri, 9 Feb 2018 13:01:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DBC5C29845 for ; Fri, 9 Feb 2018 13:01:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751077AbeBINBh (ORCPT ); Fri, 9 Feb 2018 08:01:37 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44968 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750993AbeBINBg (ORCPT ); Fri, 9 Feb 2018 08:01:36 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A85894040093; Fri, 9 Feb 2018 13:01:35 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.43.2.155]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8ECAB2166BAE; Fri, 9 Feb 2018 13:01:34 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Peter Xu Subject: [PATCH] KVM: lapic: stop advertising DIRECTED_EOI when in-kernel IOAPIC is in use Date: Fri, 9 Feb 2018 14:01:33 +0100 Message-Id: <20180209130133.28387-1-vkuznets@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 09 Feb 2018 13:01:35 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Fri, 09 Feb 2018 13:01:35 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'vkuznets@redhat.com' RCPT:'' Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Devices which use level-triggered interrupts under Windows 2016 with Hyper-V role enabled don't work: Windows disables EOI broadcast in SPIV unconditionally. Our in-kernel IOAPIC implementation emulates an old IOAPIC version which has no EOI register so EOI never happens. The issue was discovered and discussed a while ago: https://www.spinics.net/lists/kvm/msg148098.html While this is a guest OS bug (it should check that IOAPIC has the required capabilities before disabling EOI broadcast) we can workaround it in KVM: advertising DIRECTED_EOI with in-kernel IOAPIC makes little sense anyway. Signed-off-by: Vitaly Kuznetsov --- - Radim's suggestion was to disable DIRECTED_EOI unconditionally but I'm not that radical :-) In theory, we may have multiple IOAPICs in userspace in future and DIRECTED_EOI can be leveraged. --- arch/x86/kvm/lapic.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 924ac8ce9d50..5339287fee63 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -321,8 +321,16 @@ void kvm_apic_set_version(struct kvm_vcpu *vcpu) if (!lapic_in_kernel(vcpu)) return; + /* + * KVM emulates 82093AA datasheet (with in-kernel IOAPIC implementation) + * which doesn't have EOI register; Some buggy OSes (e.g. Windows with + * Hyper-V role) disable EOI broadcast in lapic not checking for IOAPIC + * version first and level-triggered interrupts never get EOIed in + * IOAPIC. + */ feat = kvm_find_cpuid_entry(apic->vcpu, 0x1, 0); - if (feat && (feat->ecx & (1 << (X86_FEATURE_X2APIC & 31)))) + if (feat && (feat->ecx & (1 << (X86_FEATURE_X2APIC & 31))) && + !ioapic_in_kernel(vcpu->kvm)) v |= APIC_LVR_DIRECTED_EOI; kvm_lapic_set_reg(apic, APIC_LVR, v); }