Re: [XEN PATCH v1] xen: mem_access: conditionally compile vm_event.c & monitor.c

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 30 Dec 2024, Sergiy Kibrik wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> 
> Extend coverage of CONFIG_MEM_ACCESS option and make the build of VM events
> and monitoring support optional.
> This is to reduce code size on Arm when this option isn't enabled.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>

I would add my reviewed-by but I wrote an early draft of this patch...

That said, it looks OK to me.

> ---
>  xen/arch/arm/Makefile      |  4 ++--
>  xen/arch/arm/vsmc.c        |  3 ++-
>  xen/common/Makefile        |  4 ++--
>  xen/include/xen/monitor.h  |  9 +++++++++
>  xen/include/xen/vm_event.h | 14 +++++++++++---
>  5 files changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 43ab5e8f25..8903eb0bf2 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -39,7 +39,7 @@ obj-$(CONFIG_LIVEPATCH) += livepatch.o
>  obj-$(CONFIG_LLC_COLORING) += llc-coloring.o
>  obj-$(CONFIG_MEM_ACCESS) += mem_access.o
>  obj-y += mm.o
> -obj-y += monitor.o
> +obj-$(CONFIG_MEM_ACCESS) += monitor.o
>  obj-y += p2m.o
>  obj-y += platform.o
>  obj-y += platform_hypercall.o
> @@ -65,7 +65,7 @@ obj-$(CONFIG_VGICV2) += vgic-v2.o
>  obj-$(CONFIG_GICV3) += vgic-v3.o
>  obj-$(CONFIG_HAS_ITS) += vgic-v3-its.o
>  endif
> -obj-y += vm_event.o
> +obj-$(CONFIG_MEM_ACCESS) += vm_event.o
>  obj-y += vtimer.o
>  obj-$(CONFIG_SBSA_VUART_CONSOLE) += vpl011.o
>  obj-y += vsmc.o
> diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
> index 62d8117a12..1c13326bdf 100644
> --- a/xen/arch/arm/vsmc.c
> +++ b/xen/arch/arm/vsmc.c
> @@ -330,7 +330,8 @@ void do_trap_smc(struct cpu_user_regs *regs, const union 
> hsr hsr)
>      }
>  
>      /* If monitor is enabled, let it handle the call. */
> -    if ( current->domain->arch.monitor.privileged_call_enabled )
> +    if ( IS_ENABLED(CONFIG_MEM_ACCESS) &&
> +         current->domain->arch.monitor.privileged_call_enabled )
>          rc = monitor_smc();
>  
>      if ( rc == 1 )
> diff --git a/xen/common/Makefile b/xen/common/Makefile
> index cba3b32733..e3c6a857ab 100644
> --- a/xen/common/Makefile
> +++ b/xen/common/Makefile
> @@ -54,7 +54,7 @@ obj-y += timer.o
>  obj-$(CONFIG_TRACEBUFFER) += trace.o
>  obj-y += version.o
>  obj-y += virtual_region.o
> -obj-y += vm_event.o
> +obj-$(CONFIG_MEM_ACCESS) += vm_event.o
>  obj-$(CONFIG_HAS_VMAP) += vmap.o
>  obj-y += vsprintf.o
>  obj-y += wait.o
> @@ -68,7 +68,7 @@ obj-$(CONFIG_COMPAT) += $(addprefix compat/,domain.o 
> memory.o multicall.o xlat.o
>  
>  ifneq ($(CONFIG_PV_SHIM_EXCLUSIVE),y)
>  obj-y += domctl.o
> -obj-y += monitor.o
> +obj-$(CONFIG_MEM_ACCESS) += monitor.o
>  obj-y += sysctl.o
>  endif
>  
> diff --git a/xen/include/xen/monitor.h b/xen/include/xen/monitor.h
> index 713d54f7c1..f1359abb94 100644
> --- a/xen/include/xen/monitor.h
> +++ b/xen/include/xen/monitor.h
> @@ -27,8 +27,17 @@
>  struct domain;
>  struct xen_domctl_monitor_op;
>  
> +#ifdef CONFIG_MEM_ACCESS
>  int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop);
>  void monitor_guest_request(void);
> +#else
> +static inline int monitor_domctl(struct domain *d,
> +                                 struct xen_domctl_monitor_op *mop)
> +{
> +    return -EINVAL;
> +}
> +static inline void monitor_guest_request(void) {}
> +#endif
>  
>  int monitor_traps(struct vcpu *v, bool sync, vm_event_request_t *req);
>  
> diff --git a/xen/include/xen/vm_event.h b/xen/include/xen/vm_event.h
> index 9a86358b42..72e720e378 100644
> --- a/xen/include/xen/vm_event.h
> +++ b/xen/include/xen/vm_event.h
> @@ -50,9 +50,6 @@ struct vm_event_domain
>      unsigned int last_vcpu_wake_up;
>  };
>  
> -/* Clean up on domain destruction */
> -void vm_event_cleanup(struct domain *d);
> -
>  /* Returns whether a ring has been set up */
>  bool vm_event_check_ring(struct vm_event_domain *ved);
>  
> @@ -88,7 +85,18 @@ void vm_event_cancel_slot(struct domain *d, struct 
> vm_event_domain *ved);
>  void vm_event_put_request(struct domain *d, struct vm_event_domain *ved,
>                            vm_event_request_t *req);
>  
> +#ifdef CONFIG_MEM_ACCESS
> +/* Clean up on domain destruction */
> +void vm_event_cleanup(struct domain *d);
>  int vm_event_domctl(struct domain *d, struct xen_domctl_vm_event_op *vec);
> +#else
> +static inline void vm_event_cleanup(struct domain *d) {}
> +static inline int vm_event_domctl(struct domain *d,
> +                                  struct xen_domctl_vm_event_op *vec)
> +{
> +    return -EINVAL;
> +}
> +#endif
>  
>  void vm_event_vcpu_pause(struct vcpu *v);
>  void vm_event_vcpu_unpause(struct vcpu *v);
> -- 
> 2.25.1
>