linux-kernel - RE: [PATCH 2/3] KVM: nVMX: Fix fail to get nested ack intr's vector during nested vmexit

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Message-ID: <A9667DDFB95DB7438FA9D7D576C3D87E0AB31AE4@SHSMSX104.ccr.corp.intel.com>
Date:	Thu, 17 Jul 2014 05:15:35 +0000
From:	"Zhang, Yang Z" <yang.z.zhang@...el.com>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	Gleb Natapov <gleb@...nel.org>, Bandan Das <bsd@...hat.com>,
	"Hu, Robert" <robert.hu@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/3] KVM: nVMX: Fix fail to get nested ack intr's vector
 during nested vmexit 

Wanpeng Li wrote on 2014-07-17:
> 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: [<ffffffff81493563>] dump_stack+0x49/0x5e 
>  [<ffffffff8103f0eb>]
> warn_slowpath_common+0x7c/0x96  [<ffffffffa059709a>] ?
> nested_vmx_vmexit+0xa4/0x233 [kvm_intel]  [<ffffffff8103f11a>]
> warn_slowpath_null+0x15/0x17  [<ffffffffa059709a>]
> nested_vmx_vmexit+0xa4/0x233 [kvm_intel]  [<ffffffffa0594295>] ?
> nested_vmx_exit_handled+0x6a/0x39e [kvm_intel]  [<ffffffffa0537931>] ?
> kvm_apic_has_interrupt+0x80/0xd5 [kvm]  [<ffffffffa05972ec>]
> vmx_check_nested_events+0xc3/0xd3 [kvm_intel]  [<ffffffffa051ebe9>]
> inject_pending_event+0xd0/0x16e [kvm]  [<ffffffffa051efa0>]
> 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 <wanpeng.li@...ux.intel.com>

Reviewed-by: Yang Zhang <yang.z.zhang@...el.com>

> ---
>  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..31f1479 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_get_apic_interrupt(vcpu);
>  		WARN_ON(irq < 0);
>  		vmcs12->vm_exit_intr_info = irq |
>  			INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR;


Best regards,
Yang


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