Re: [PATCH v1] x86/domain: revisit logging in arch_domain_create()

["Roger Pau Monné" <roger.pau@citrix.com>]

On Mon, Mar 31, 2025 at 09:34:24PM +0000, dmkhn@proton.me wrote:
> From: Denis Mukhin <dmukhin@ford.com>
> 
> Use %pd in all logs issued from arch_domain_create().
> 
> Also, expand error message in arch_domain_create() under
> !emulation_flags_ok() case to help debugging.
> 
> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> ---
> The origin of the patch is:
>   https://lore.kernel.org/xen-devel/20250103-vuart-ns8250-v3-v1-6-c5d36b31d66c@ford.com/
> ---
>  xen/arch/x86/domain.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index a42fa54805..15c5e2a652 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -798,13 +798,12 @@ int arch_domain_create(struct domain *d,
>      {
>          if ( !opt_allow_unsafe )
>          {
> -            printk(XENLOG_G_ERR "Xen does not allow DomU creation on this CPU"
> -                   " for security reasons.\n");
> +            printk(XENLOG_G_ERR "%pd: Xen does not allow DomU creation on this CPU"
> +                   " for security reasons.\n", d);

Since you are already touching this, I would switch to gprintk, and
avoid splitting the lines:

            gprintk(XENLOG_ERR,
                    "%pd: Xen does not allow DomU creation on this CPU for security reasons.\n",
                    d);

Same for the other messages below.

>              return -EPERM;
>          }
>          printk(XENLOG_G_WARNING
> -               "Dom%d may compromise security on this CPU.\n",
> -               d->domain_id);
> +               "%pd: domain may compromise security on this CPU.\n", d);
>      }
>  
>      emflags = config->arch.emulation_flags;
> @@ -814,16 +813,19 @@ int arch_domain_create(struct domain *d,
>  
>      if ( emflags & ~XEN_X86_EMU_ALL )
>      {
> -        printk(XENLOG_G_ERR "d%d: Invalid emulation bitmap: %#x\n",
> -               d->domain_id, emflags);
> +        printk(XENLOG_G_ERR "%pd: Invalid emulation bitmap: %#x\n",
> +               d, emflags);
>          return -EINVAL;
>      }
>  
>      if ( !emulation_flags_ok(d, emflags) )
>      {
> -        printk(XENLOG_G_ERR "d%d: Xen does not allow %s domain creation "
> +        printk(XENLOG_G_ERR "%pd: Xen does not allow %s %sdomain creation "
>                 "with the current selection of emulators: %#x\n",
> -               d->domain_id, is_hvm_domain(d) ? "HVM" : "PV", emflags);
> +               d,
> +               is_hvm_domain(d) ? "HVM" : "PV",
> +               is_hardware_domain(d) ? "(hardware) " : "",

I wouldn't use parentheses around hardware, but that's just my taste.

Thanks, Roger.