Re: [PATCH] xen/keyhandler: Move key_table[] into __ro_after_init

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Sep 12, 2024 at 01:51:54PM +0100, Andrew Cooper wrote:
> All registration is done at boot.  Almost...
> 
> iommu_dump_page_tables() is registered in iommu_hwdom_init(), which is called
> twice when LATE_HWDOM is in use.
> 
> register_irq_keyhandler() has an ASSERT() guarding againt multiple
> registration attempts, and the absence of bug reports hints at how many
> configurations use LATE_HWDOM in practice.
> 
> Move the registration into iommu_setup() just after printing the overall
> status of the IOMMU.  For starters, the hardware domain is specifically
> excluded by iommu_dump_page_tables().
> 
> ept_dump_p2m_table is registered in setup_ept_dump() which is non-__init, but
> whose sole caller, start_vmx(), is __init.  Move setup_ept_dump() to match.
> 
> With these two tweeks, all keyhandler reigstration is from __init functions,
> so register_{,irq_}keyhandler() can move, and key_table[] can become
> __ro_after_init.
> 
> No practical change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Daniel Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> CC: Jason Andryuk <jandryuk@xxxxxxxxx>
> 
> CC'ing some OpenXT folks just FYI.
> ---
>  xen/arch/x86/mm/p2m-ept.c       |  2 +-
>  xen/common/keyhandler.c         | 10 +++++-----
>  xen/drivers/passthrough/iommu.c |  4 ++--
>  3 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
> index 2ea574ca6aef..21728397f9ac 100644
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -1497,7 +1497,7 @@ static void cf_check ept_dump_p2m_table(unsigned char 
> key)
>      rcu_read_unlock(&domlist_read_lock);
>  }
>  
> -void setup_ept_dump(void)
> +void __init setup_ept_dump(void)

I would be tempted to just drop this function altogether and open-code
the call to register_keyhandler().

Thanks, Roger.