linux-kernel - Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since race

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Date:	Fri, 4 Jul 2014 14:08:31 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Jan Kiszka <jan.kiszka@...mens.com>
Cc:	Bandan Das <bsd@...hat.com>, Paolo Bonzini <pbonzini@...hat.com>,
	Gleb Natapov <gleb@...nel.org>,
	Hu Robert <robert.hu@...el.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1
 since race

On Fri, Jul 04, 2014 at 07:43:14AM +0200, Jan Kiszka wrote:
>On 2014-07-04 04:52, Wanpeng Li wrote:
>> On Thu, Jul 03, 2014 at 01:27:05PM -0400, Bandan Das wrote:
>> [...]
>>> # modprobe kvm_intel ept=0 nested=1 enable_shadow_vmcs=0
>>>
>>> The Host CPU - Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
>>> qemu cmd to run L1 - 
>>> # qemu-system-x86_64 -drive file=level1.img,if=virtio,id=disk0,format=raw,cache=none,werror=stop,rerror=stop,aio=threads -drive file=level2.img,if=virtio,id=disk1,format=raw,cache=none,werror=stop,rerror=stop,aio=threads -vnc :2 --enable-kvm -monitor stdio -m 4G -net nic,macaddr=00:23:32:45:89:10 -net tap,ifname=tap0,script=/etc/qemu-ifup,downscript=no -smp 4 -cpu Nehalem,+vmx -serial pty
>>>
>>> qemu cmd to run L2 -
>>> # sudo qemu-system-x86_64 -hda VM/level2.img -vnc :0 --enable-kvm -monitor stdio -m 2G -smp 2 -cpu Nehalem -redir tcp:5555::22
>>>
>>> Additionally,
>>> L0 is FC19 with 3.16-rc3
>>> L1 and L2 are Ubuntu 14.04 with 3.13.0-24-generic
>>>
>>> Then start a kernel compilation inside L2 with "make -j3"
>>>
>>> There's no call trace on L0, both L0 and L1 are hung (or rather really slow) and
>>> L1 serial spews out CPU softlock up errors. Enabling panic on softlockup on L1 will give
>>> a trace with smp_call_function_many() I think the corresponding code in kernel/smp.c that
>>> triggers this is
>>>
>>> WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
>>>                      && !oops_in_progress && !early_boot_irqs_disabled);
>>>
>>> I know in most cases this is usually harmless, but in this specific case,
>>> it seems it's stuck here forever.
>>>
>>> Sorry, I don't have a L1 call trace handy atm, I can post that if you are interested.
>>>
>>> Note that this can take as much as 30 to 40 minutes to appear but once it does,
>>> you will know because both L1 and L2 will be stuck with the serial messages as I mentioned
>>> before. From my side, let me try this on another system to rule out any machine specific
>>> weirdness going on..
>>>
>> 
>> Thanks for your pointing out. 
>> 
>>> Please let me know if you need any further information.
>>>
>> 
>> I just run kvm-unit-tests w/ vmx.flat and eventinj.flat.
>> 
>> 
>> w/ vmx.flat and w/o my patch applied 
>> 
>> [...]
>> 
>> Test suite : interrupt
>> FAIL: direct interrupt while running guest
>> PASS: intercepted interrupt while running guest
>> FAIL: direct interrupt + hlt
>> FAIL: intercepted interrupt + hlt
>> FAIL: direct interrupt + activity state hlt
>> FAIL: intercepted interrupt + activity state hlt
>> PASS: running a guest with interrupt acknowledgement set
>> SUMMARY: 69 tests, 6 failures
>> 
>> w/ vmx.flat and w/ my patch applied 
>> 
>> [...]
>> 
>> Test suite : interrupt
>> PASS: direct interrupt while running guest
>> PASS: intercepted interrupt while running guest
>> PASS: direct interrupt + hlt
>> FAIL: intercepted interrupt + hlt
>> PASS: direct interrupt + activity state hlt
>> PASS: intercepted interrupt + activity state hlt
>> PASS: running a guest with interrupt acknowledgement set
>> 
>> SUMMARY: 69 tests, 2 failures 
>
>Which version (hash) of kvm-unit-tests are you using? All tests up to
>307621765a are running fine here, but since a0e30e712d not much is
>completing successfully anymore:
>

I just git pull my kvm-unit-tests to latest, the last commit is daeec9795d.

>enabling apic
>paging enabled
>cr0 = 80010011
>cr3 = 7fff000
>cr4 = 20
>PASS: test vmxon with FEATURE_CONTROL cleared
>PASS: test vmxon without FEATURE_CONTROL lock
>PASS: test enable VMX in FEATURE_CONTROL
>PASS: test FEATURE_CONTROL lock bit
>PASS: test vmxon
>FAIL: test vmptrld
>PASS: test vmclear
>init_vmcs : make_vmcs_current error
>FAIL: test vmptrst
>init_vmcs : make_vmcs_current error
>vmx_run : vmlaunch failed.
>FAIL: test vmlaunch
>FAIL: test vmlaunch
>
>SUMMARY: 10 tests, 4 unexpected failures


/opt/qemu/bin/qemu-system-x86_64 -enable-kvm -device pc-testdev -serial stdio 
-device isa-debug-exit,iobase=0xf4,iosize=0x4 -kernel ./x86/vmx.flat -cpu host

Test suite : interrupt
PASS: direct interrupt while running guest
PASS: intercepted interrupt while running guest
PASS: direct interrupt + hlt
FAIL: intercepted interrupt + hlt
PASS: direct interrupt + activity state hlt
PASS: intercepted interrupt + activity state hlt
PASS: running a guest with interrupt acknowledgement set

SUMMARY: 69 tests, 2 failures

However, interrupted interrupt + hlt always fail w/ and w/o my patch.

Regards,
Wanpeng Li 

>
>
>Jan
>
>-- 
>Siemens AG, Corporate Technology, CT RTC ITP SES-DE
>Corporate Competence Center Embedded Linux
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