Re: vpmu=1 and running 'perf top' within a PVHVM guest eventually hangs dom0 and hypervisor has stuck vCPUS. Romley-EP (model=45, stepping=2)

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Mar 13, 2013 at 08:28:57AM +0000, Jan Beulich wrote:
> >>> On 12.03.13 at 19:50, Boris Ostrovsky <boris.ostrovsky@oracle.com> wrote:
> > On 03/12/2013 01:30 PM, Konrad Rzeszutek Wilk wrote:
> >> This issue I am encountering seems to only happen on multi-socket
> >> machines.
> > 
> > I believe I was able to reproduce this (once) on my laptop.
> > 
> >> It also does not help that the only multi-socket box I have is
> >> an Romley-EP (so two socket SandyBridge CPUs). The other
> >> SandyBridge boxes I've (one socket) are not showing this. Granted
> >> they are also a different model (42).
> >>
> >> The problem is that when I run 'perf top' within an SMP PVHVM
> >> guest, after a couple of seconds or minutes the guest hangs.
> >> Hypervisor ends up stuck too looping, and then the dom0 ends
> >> up hanging as well.
> >>
> >> Dumping the cpu registers (Ctrl-A x3, then 'd'
> >> shows that the guest is pretty firmly stuck in vmx_vmexit_handler:
> >>
> >> (XEN)    [<ffff82c4c01d386f>] vmx_vmexit_handler+0x22f/0x174
> > 
> > And in my case this address is the second instruction after STI, i.e. we
> > are right at the point where interrupts got enabled.
> 
> As I didn't notice anything regarding the top commit of the tree
> you used - was this with 7dd3b06 already included?

I did include Tim's patch in the tree (this was before it got committed
in). I had these right above
ba9ef879973f9bee4b72c8f1d3ef816bc58e5fdc (x86: minor fix for rdmsrl):

b77cd15 trace: Add reason for NMI exit TRAP
ad8523a trace: Add the other variant of do_block.
4fb1793 trace: Add trace events for IRQ activities.
e71031c trace: Use correct trace class for power management changes.
7b185ec vmx/nmi: Do not use self_nmi() in VMEXIT handler]
020ad4c vpmu intel: pass through cpuid bits when BTS is enabled
650f7f0 Always save/restore performance counters when HVM guest switching VCPU

and also without them.

> 
> Jan
> 
> 
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