Re: [Xen-devel] [PATCH V5] vm_event: Allow subscribing to write events for specific MSR-s

[Julien Grall <julien.grall@xxxxxxx>]

Hi Razvan,

On 26/04/2016 09:49, Razvan Cojocaru wrote:
> diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
> index 2906407..1ba12cb 100644
> --- a/xen/common/vm_event.c
> +++ b/xen/common/vm_event.c
> @@ -27,6 +27,7 @@
>   #include <xen/mem_access.h>
>   #include <asm/p2m.h>
>   #include <asm/altp2m.h>
> +#include <asm/monitor.h>
>   #include <asm/vm_event.h>
>   #include <xsm/xsm.h>
>
> @@ -665,6 +666,9 @@ int vm_event_domctl(struct domain *d, 
> xen_domctl_vm_event_op_t *vec,
>           {
>           case XEN_VM_EVENT_ENABLE:
>               /* domain_pause() not required here, see XSA-99 */
> +            rc = arch_monitor_init_domain(d);
For x86, this function will allocate memory unconditionally. I cannot 
find anything which could prevent someone to call XEN_VM_EVENT_ENABLE 
twice. So Xen would leak memory for the previous allocation.
> +            if ( rc )
> +                break;
>               rc = vm_event_enable(d, vec, ved, _VPF_mem_access,
>                                    HVM_PARAM_MONITOR_RING_PFN,
>                                    monitor_notification);
> @@ -675,6 +679,7 @@ int vm_event_domctl(struct domain *d, 
> xen_domctl_vm_event_op_t *vec,
>               {
>                   domain_pause(d);
>                   rc = vm_event_disable(d, ved);
> +                arch_monitor_cleanup_domain(d);
>                   domain_unpause(d);
>               }
>               break;
> diff --git a/xen/include/asm-arm/monitor.h b/xen/include/asm-arm/monitor.h
> index 6e36e99..57a9d91 100644
> --- a/xen/include/asm-arm/monitor.h
> +++ b/xen/include/asm-arm/monitor.h
> @@ -46,4 +46,17 @@ int arch_monitor_domctl_event(struct domain *d,
>       return -EOPNOTSUPP;
>   }
>
> +static inline
> +int arch_monitor_init_domain(struct domain *d)
> +{
> +    /* No arch-specific domain initialization on ARM. */
> +    return -EOPNOTSUPP;
Shouldn't we return 0 in this case?

> +}
> +
> +static inline
> +void arch_monitor_cleanup_domain(struct domain *d)
> +{
> +    /* No arch-specific domain cleanup on ARM. */
> +}
> +
>   #endif /* __ASM_ARM_MONITOR_H__ */
Regards,

--
Julien Grall

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