Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932104AbaGQKDQ (ORCPT ); Thu, 17 Jul 2014 06:03:16 -0400 Received: from mga11.intel.com ([192.55.52.93]:50394 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756175AbaGQKDN (ORCPT ); Thu, 17 Jul 2014 06:03:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,677,1400050800"; d="scan'208,223";a="563132659" Date: Thu, 17 Jul 2014 18:03:55 +0800 From: Wanpeng Li To: "Zhang, Yang Z" , Paolo Bonzini Cc: Jan Kiszka , Marcelo Tosatti , Gleb Natapov , Bandan Das , "Hu, Robert" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/3] KVM: nVMX: Fix fail to get nested ack intr's vector during nested vmexit Message-ID: <20140717100355.GB9118@kernel> Reply-To: Wanpeng Li References: <1405573011-41330-1-git-send-email-wanpeng.li@linux.intel.com> <1405573011-41330-2-git-send-email-wanpeng.li@linux.intel.com> <53C78E37.5090807@redhat.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="VrqPEDrXMn8OVzN4" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --VrqPEDrXMn8OVzN4 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Jul 17, 2014 at 09:13:56AM +0000, Zhang, Yang Z wrote: >Paolo Bonzini wrote on 2014-07-17: >> Il 17/07/2014 06:56, Wanpeng Li ha scritto: >>> && nested_exit_intr_ack_set(vcpu)) { >>> int irq = kvm_cpu_get_interrupt(vcpu); >>> + >>> + if (irq < 0 && kvm_apic_vid_enabled(vcpu->kvm)) >>> + irq = kvm_get_apic_interrupt(vcpu); >> >> There's something weird in this patch. If you "inline" >> kvm_cpu_get_interrupt, what you get is this: >> >> int irq; >> /* Beginning of kvm_cpu_get_interrupt... */ >> if (!irqchip_in_kernel(v->kvm)) >> irq = v->arch.interrupt.nr; >> else { >> irq = kvm_cpu_get_extint(v); /* PIC */ >> if (!kvm_apic_vid_enabled(v->kvm) && irq == -1) >> irq = kvm_get_apic_interrupt(v); /* APIC */ >> } >> >> /* kvm_cpu_get_interrupt done. */ >> if (irq < 0 && kvm_apic_vid_enabled(vcpu->kvm)) >> irq = kvm_get_apic_interrupt(vcpu); >> >> There are just two callers of kvm_cpu_get_interrupt, and the other is >> protected by kvm_cpu_has_injectable_intr so it won't be executed if >> virtual interrupt delivery is enabled. So you patch is effectively the same as this: >> >> diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index >> bd0da43..a1ec6a5 100644 --- a/arch/x86/kvm/irq.c +++ >> b/arch/x86/kvm/irq.c @@ -108,7 +108,7 @@ int >> kvm_cpu_get_interrupt(struct kvm_vcpu *v) >> >> vector = kvm_cpu_get_extint(v); >> - if (kvm_apic_vid_enabled(v->kvm) || vector != -1) >> + if (vector != -1) >> return vector; /* PIC */ >> >> return kvm_get_apic_interrupt(v); /* APIC */ >> But in kvm_get_apic_interrupt I have just added this comment: >> >> /* Note that we never get here with APIC virtualization >> * enabled. */ >> >> because kvm_get_apic_interrupt calls apic_set_isr, and apic_set_isr >> must never be called with APIC virtualization enabled either. With >> APIC virtualization enabled, isr_count is always 1, and >> highest_isr_cache is always -1, and apic_set_isr breaks both of these invariants. >> > >You are right. kvm_lapic_find_highest_irr should be the right one. > That is my original proposal solution of this bug. However, what I concern after more think is since kvm_lapic_find_highest_irr will not clear irr, if the intr will be injected by kvm_86_ops->hwapic_irr_update(vcpu, kvm_lapic_find_highest_irr(vcpu)) which called by vcpu_enter_guest() again? Any idea, Paolo? Regards, Wanpeng Li >> Paolo > > >Best regards, >Yang > --VrqPEDrXMn8OVzN4 Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0001-fix-warning.patch" >From b14c444e073a21560961b37be643b78c6c9cba17 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Thu, 17 Jul 2014 17:41:28 +0800 Subject: [PATCH v2] KVM: nVMX: Fix fail to get nested ack intr's vector during nested vmexit WARNING: CPU: 9 PID: 7251 at arch/x86/kvm/vmx.c:8719 nested_vmx_vmexit+0xa4/0x233 [kvm_intel]() Modules linked in: tun nfsv3 nfs_acl auth_rpcgss oid_registry nfsv4 dns_resolver nfs fscache lockd sunrpc pci_stub netconsole kvm_intel kvm bridge stp llc autofs4 8021q ipv6 uinput joydev microcode pcspkr igb i2c_algo_bit ehci_pci ehci_hcd e1000e ixgbe ptp pps_core hwmon mdio i2c_i801 i2c_core tpm_tis tpm ipmi_si ipmi_msghandler isci libsas scsi_transport_sas button dm_mirror dm_region_hash dm_log dm_mod CPU: 9 PID: 7251 Comm: qemu-system-x86 Tainted: G W 3.16.0-rc1 #2 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 000000000000220f ffff880ffd107bf8 ffffffff81493563 000000000000220f 0000000000000000 ffff880ffd107c38 ffffffff8103f0eb ffff880ffd107c48 ffffffffa059709a ffff881ffc9e0040 ffff8800b74b8000 00000000ffffffff Call Trace: [] dump_stack+0x49/0x5e [] warn_slowpath_common+0x7c/0x96 [] ? nested_vmx_vmexit+0xa4/0x233 [kvm_intel] [] warn_slowpath_null+0x15/0x17 [] nested_vmx_vmexit+0xa4/0x233 [kvm_intel] [] ? nested_vmx_exit_handled+0x6a/0x39e [kvm_intel] [] ? kvm_apic_has_interrupt+0x80/0xd5 [kvm] [] vmx_check_nested_events+0xc3/0xd3 [kvm_intel] [] inject_pending_event+0xd0/0x16e [kvm] [] vcpu_enter_guest+0x319/0x704 [kvm] After commit 77b0f5d (KVM: nVMX: Ack and write vector info to intr_info if L1 asks us to), "Acknowledge interrupt on exit" behavior can be emulated. Current logic will ask for intr vector if it is nested vmexit and VM_EXIT_ACK_INTR_ON_EXIT is set by L1. However, intr vector for posted intr can't be got by generic read pending interrupt vector and intack routine, there is a requirement to sync from pir to irr. This patch fix it by ask the intr vector after sync pir to irr. Signed-off-by: Wanpeng Li --- v1 -> v2: * replace kvm_get_apic_interrupt() by kvm_lapic_find_highest_irr() arch/x86/kvm/lapic.c | 1 + arch/x86/kvm/vmx.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 0069118..b7d45dc 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1637,6 +1637,7 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) apic_clear_irr(vector, apic); return vector; } +EXPORT_SYMBOL_GPL(kvm_get_apic_interrupt); void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 4ae5ad8..a704f71 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8697,6 +8697,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, if ((exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) && nested_exit_intr_ack_set(vcpu)) { int irq = kvm_cpu_get_interrupt(vcpu); + + if (irq < 0 && kvm_apic_vid_enabled(vcpu->kvm)) + irq = kvm_lapic_find_highest_irr(vcpu); WARN_ON(irq < 0); vmcs12->vm_exit_intr_info = irq | INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR; -- 1.9.1 --VrqPEDrXMn8OVzN4-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/