Re: [Xen-devel] [PATCH v4 15/17] x86/VPMU: NMI-based VPMU support

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.02.14 at 17:31, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 02/04/2014 06:48 AM, Jan Beulich wrote:
>> And then I'm still missing a reasonable level of analysis that the
>> previously non-NMI-only interrupt handler is now safe to use in NMI
>> context.
> 
> How about this?

Looks okay, except ...

> With send_guest_vcpu_virq() and hvm_get_segment_register() for PV(H) and 
> vlapic accesses for HVM moved to sofint, the only routines/macros that 
> vpmu_do_interrupt() calls in NMI mode are:
> * memcpy()
> * querying domain type (is_XX_domain())
> * guest_cpu_user_regs()
> * XLAT_cpu_user_regs()
> * raise_softirq()
> * vcpu_vpmu()
> * vpmu_ops->arch_vpmu_save()
> * vpmu_ops->do_interrupt() (in the future for PVH support)
> 
> The latter two can only access PMU MSRs.

... that this additionally needs to exclude things like
{rd,wr}msr_safe() (i.e. stuff raising exceptions that normally
get recovered from).

Jan


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