Re: [PATCH v5 04/13] xen: extend domctl interface for cache coloring

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.01.2024 10:51, Carlo Nonato wrote:
> --- a/xen/arch/arm/llc-coloring.c
> +++ b/xen/arch/arm/llc-coloring.c
> @@ -9,6 +9,7 @@
>   *    Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
>   */
>  #include <xen/errno.h>
> +#include <xen/guest_access.h>
>  #include <xen/keyhandler.h>
>  #include <xen/llc-coloring.h>
>  #include <xen/param.h>
> @@ -278,6 +279,22 @@ int dom0_set_llc_colors(struct domain *d)
>      return domain_check_colors(d);
>  }
>  
> +int domain_set_llc_colors_domctl(struct domain *d,
> +                                 const struct xen_domctl_set_llc_colors 
> *config)
> +{
> +    if ( d->num_llc_colors )
> +        return -EEXIST;
> +
> +    if ( domain_alloc_colors(d, config->num_llc_colors) )
> +        return -ENOMEM;
> +
> +    if ( copy_from_guest(d->llc_colors, config->llc_colors,
> +                         config->num_llc_colors) )
> +        return -EFAULT;
> +
> +    return domain_check_colors(d);
> +}

What part of this is Arm-specific? I ask in particular because while you
place this in an Arm-specific source file, ...

> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -8,6 +8,7 @@
>  
>  #include <xen/types.h>
>  #include <xen/lib.h>
> +#include <xen/llc-coloring.h>
>  #include <xen/err.h>
>  #include <xen/mm.h>
>  #include <xen/sched.h>
> @@ -858,6 +859,16 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> u_domctl)
>                  __HYPERVISOR_domctl, "h", u_domctl);
>          break;
>  
> +    case XEN_DOMCTL_set_llc_colors:
> +        if ( !llc_coloring_enabled )
> +            break;
> +
> +        ret = domain_set_llc_colors_domctl(d, &op->u.set_llc_colors);
> +        if ( ret == -EEXIST )
> +            printk(XENLOG_ERR
> +                   "Can't set LLC colors on an already created domain\n");
> +        break;
> +
>      default:
>          ret = arch_do_domctl(op, d, u_domctl);
>          break;

... you don't handle the new domctl in Arm's arch_do_domctl().

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -21,7 +21,7 @@
>  #include "hvm/save.h"
>  #include "memory.h"
>  
> -#define XEN_DOMCTL_INTERFACE_VERSION 0x00000016
> +#define XEN_DOMCTL_INTERFACE_VERSION 0x00000017

There's no need for such a bump when ...

> @@ -1190,6 +1190,12 @@ struct xen_domctl_vmtrace_op {
>  typedef struct xen_domctl_vmtrace_op xen_domctl_vmtrace_op_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_domctl_vmtrace_op_t);
>  
> +struct xen_domctl_set_llc_colors {
> +    /* IN LLC coloring parameters */
> +    unsigned int num_llc_colors;
> +    XEN_GUEST_HANDLE_64(uint) llc_colors;
> +};
> +
>  struct xen_domctl {
>      uint32_t cmd;
>  #define XEN_DOMCTL_createdomain                   1
> @@ -1277,6 +1283,7 @@ struct xen_domctl {
>  #define XEN_DOMCTL_vmtrace_op                    84
>  #define XEN_DOMCTL_get_paging_mempool_size       85
>  #define XEN_DOMCTL_set_paging_mempool_size       86
> +#define XEN_DOMCTL_set_llc_colors                87
>  #define XEN_DOMCTL_gdbsx_guestmemio            1000
>  #define XEN_DOMCTL_gdbsx_pausevcpu             1001
>  #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
> @@ -1339,6 +1346,7 @@ struct xen_domctl {
>          struct xen_domctl_vuart_op          vuart_op;
>          struct xen_domctl_vmtrace_op        vmtrace_op;
>          struct xen_domctl_paging_mempool    paging_mempool;
> +        struct xen_domctl_set_llc_colors    set_llc_colors;
>          uint8_t                             pad[128];
>      } u;
>  };

... all you do is add a new domctl.

As to the new struct - you'll want to use uint<N>_t there, not
unsigned int.

Jan