Re: commit f8f559422b (KVM: MMU: fast invalidate all mmio sptes) causes hang

[Markus Trippelsdorf <markus@trippelsdorf.de>]

On 2013.07.17 at 19:42 +0300, Gleb Natapov wrote:
> On Wed, Jul 17, 2013 at 06:32:15PM +0200, Markus Trippelsdorf wrote:
> > The following commit:
> >  commit f8f559422b6c6a05469dfde614b67789b6142cb5
> >  Author: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
> >  Date:   Fri Jun 7 16:51:26 2013 +0800
> > 
> >     KVM: MMU: fast invalidate all mmio sptes
> > 
> > causes my kvm qemu qcow2 images to hang when they switch from the boot
> > console to the desktop. For example:
> >  qemu-system-x86_64 -enable-kvm -net nic,vlan=0,model=virtio -net user -drive file=ubuntu,if=virtio,cache=unsafe -smp 2 -m 1024
> > boots normally at first, but then hangs as soon as Xorg gets started.`
> > 
> Which guest is is exactly and how reproducible is this?

Ubuntu 12.04.
It's 100% reproducible or else it wouldn't have been so easily
bisectable.

> > Perf top shows:
> >  20.99%  [kernel]                                  [k] svm_vcpu_run
> >  17.24%  [kernel]                                  [k] handle_mmio_page_fault_common
> >  15.61%  [kernel]                                  [k] kvm_arch_vcpu_ioctl_run
> >  12.49%  [kernel]                                  [k] fast_page_fault.part.78
> > 
> > I'm running:
> > QEMU emulator version 1.4.2 
> > on an AMD PhenomII X4 CPU.
> > 
> What is the output of "cat /proc/cpuinfo"?


processor	: 0
vendor_id	: AuthenticAMD
cpu family	: 16
model		: 4
model name	: AMD Phenom(tm) II X4 955 Processor
stepping	: 2
microcode	: 0x10000db
cpu MHz		: 800.000
cache size	: 512 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 4
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 5
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock nrip_save
bogomips	: 6424.73
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate
...
*4

-- 
Markus