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

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 04/26/2014 04:33 AM, Tian, Kevin wrote:
>> From: Boris Ostrovsky [mailto:boris.ostrovsky@oracle.com]
>> 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@oracle.com>
>> ---
>>   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@intel.com>