Re: [PATCH V3] x86/monitor: Disallow setting mem_access_emulate_each_rep when vm_event is NULL

[Tamas K Lengyel <tamas@tklengyel.com>]

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On Tue, May 3, 2016 at 2:18 AM, Razvan Cojocaru <rcojocaru@bitdefender.com>
wrote:

> On 05/03/2016 11:14 AM, Jan Beulich wrote:
> >>>> On 29.04.16 at 18:12, <rcojocaru@bitdefender.com> wrote:
> >> On 04/09/16 08:54, Razvan Cojocaru wrote:
> >>> It is meaningless (and potentially dangerous - see
> hvmemul_virtual_to_linear())
> >>> to set mem_access_emulate_each_rep before xc_monitor_enable() (which
> allocates
> >>> vcpu->arch.vm_event) has been called, so return an error from the
> >>> XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP hypercall when that is the case.
> >>>
> >>> Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
> >>> Reviewed-by: Andrew Cooper <andrew.cooper3@citirx.com>
> >>>
> >>> ---
> >>> Changes since V2:
> >>>  - Updated the if() condition as recommended by Andrew Cooper.
> >>>  - Added Andrew Cooper's Reviewed-by.
> >>> ---
> >>>  xen/include/asm-x86/monitor.h | 16 +++++++++++++---
> >>>  1 file changed, 13 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/xen/include/asm-x86/monitor.h
> b/xen/include/asm-x86/monitor.h
> >>> index 0954b59..d367099 100644
> >>> --- a/xen/include/asm-x86/monitor.h
> >>> +++ b/xen/include/asm-x86/monitor.h
> >>> @@ -32,19 +32,29 @@
> >>>  static inline
> >>>  int arch_monitor_domctl_op(struct domain *d, struct
> xen_domctl_monitor_op *mop)
> >>>  {
> >>> +    int rc = 0;
> >>> +
> >>>      switch ( mop->op )
> >>>      {
> >>>      case XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP:
> >>>          domain_pause(d);
> >>> -        d->arch.mem_access_emulate_each_rep = !!mop->event;
> >>> +        /*
> >>> +         * Enabling mem_access_emulate_each_rep without a vm_event
> subscriber
> >>> +         * is meaningless.
> >>> +         */
> >>> +        if ( d->max_vcpus && d->vcpu[0] && d->vcpu[0]->arch.vm_event )
> >>> +            d->arch.mem_access_emulate_each_rep = !!mop->event;
> >>> +        else
> >>> +            rc = -EINVAL;
> >>> +
> >>>          domain_unpause(d);
> >>>          break;
> >>>
> >>>      default:
> >>> -        return -EOPNOTSUPP;
> >>> +        rc = -EOPNOTSUPP;
> >>>      }
> >>>
> >>> -    return 0;
> >>> +    return rc;
> >>>  }
> >>>
> >>>  int arch_monitor_domctl_event(struct domain *d,
> >>
> >> According to the previous list discussion with Andrew Cooper, this fix
> >> might be considered for the 4.7 release, so CC-ing Wei for a release
> >> ack, as suggested.
> >
> > Even if - without the pending ./MAINTAINERS adjustment - not
> > formally required, I don't understand why you didn't Cc Tamas on
> > this patch. I don't think this should go in without his ack.
>
> Of course, I was under the impression that he was in the recipients list
> (I let scripts/maintaners.pl do the work and didn't pay much attention
> to its output).
>
> By all means.
>

The maintainers file wasn't covering this header properly. Fixed in my
other patch-set.

Acked-by: Tamas K Lengyel <tamas@tklengyel.com>

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