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

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> 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?

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

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