Re: [Xen-devel] [PATCH v5 RESEND 12/17] x86/VPMU: Handle PMU interrupts for PV guests

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 04/26/2014 04:33 AM, Tian, Kevin wrote:
> > From: Boris Ostrovsky [mailto:boris.ostrovsky@xxxxxxxxxx]
> > Sent: Wednesday, April 23, 2014 8:51 PM
> >
> > Add support for handling PMU interrupts for PV guests.
> >
> > VPMU for the interrupted VCPU is unloaded until the guest issues
> > XENPMU_flush
> > hypercall. This allows the guest to access PMU MSR values that are stored in
> > VPMU context which is shared between hypervisor and domain, thus avoiding
> > traps to hypervisor.
> >
> > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > ---
> >   xen/arch/x86/hvm/vpmu.c  | 110
> > ++++++++++++++++++++++++++++++++++++++++++++---
> >   xen/include/public/pmu.h |   7 +++
> >   2 files changed, 112 insertions(+), 5 deletions(-)
> >
> > diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c
> > index 789eb2a..abc4c1f 100644
> > --- a/xen/arch/x86/hvm/vpmu.c
> > +++ b/xen/arch/x86/hvm/vpmu.c
> >   int vpmu_do_interrupt(struct cpu_user_regs *regs)
> >   {
> >       struct vcpu *v = current;
> > -    struct vpmu_struct *vpmu = vcpu_vpmu(v);
> > +    struct vpmu_struct *vpmu;
> > +
> > +    /* dom0 will handle this interrupt */
> > +    if ( v->domain->domain_id >= DOMID_FIRST_RESERVED )
> > +        v = dom0->vcpu[smp_processor_id() % dom0->max_vcpus];
> > +
> > +    vpmu = vcpu_vpmu(v);
> > +    if ( !is_hvm_domain(v->domain) )
> > +    {
> > +        /* PV guest or dom0 is doing system profiling */
> > +        const struct cpu_user_regs *gregs;
> > +        int err;
> a bit misleading. if non-dom0, it should be guest profiling only, right?
Right. I meant that either a regular PV guest profiling itself or dom0 
profiling itself and the hypervisor. I possibly also meant here 
XENPMU_MODE_PRIV mode (where dom0 profiles everyone --- itself, 
hypervisor and all guests) but that it introduced in a later patch and 
shouldn't be here yet)
I'll re-phrase it.

-boris

> Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

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