Re: [PATCH v11 2/5] s390/pci: Improve function measurement state management

[Niklas Schnelle]

On Wed, 2026-10-28 at 11:43 -0400, Omar Elghoul wrote:
> When a zPCI function is disabled and re-enabled, the firmware implicitly
> disables function measurement while the kernel still believes it is
> enabled, leading to a disconnect between the user-visible state and the
> actual device state.
> 
> Add the statistics_on field to struct zpci_dev to track the desired FMB
> state. Introduce the functions zpci_fmb_request_on() and off(), which
> defer to zpci_fmb_enable() or disable() to perform the actual firmware

Super nit: "off()" on its own reads as if that was the actual name. I'd
either use "…_off()", "zpci_fmb_request_on()/_off()" or just the full
name for both. Same for "disable()". If this is all it's probably not
enough of a reason to respin.

> change. This decouples the enablement or disablement step from managing
> the user's requested state.
> 
> Preserve the state in pcibios_enable_device(), pcibios_disable_device(),

Nit: Not a native speaker but I think this isn't really "preserve" but
rather "restore" with the word changed you could drop the second half
of the sentence.

> and zpci_reenable_device(), so measurement is restored automatically
> after a re-enable. New devices start with measurement on by default,
> unchanged from before.
> 
> Signed-off-by: Omar Elghoul <oelghoul@xxxxxxxxxxxxx>
> ---
>  arch/s390/include/asm/pci.h |  7 +++--
>  arch/s390/pci/pci.c         | 60 +++++++++++++++++++++++++++++++++----
>  arch/s390/pci/pci_debug.c   |  6 ++--
>  3 files changed, 63 insertions(+), 10 deletions(-)
> 

The patch looks good but I think there is an interaction with patch 3
that may cause a change in this patch. That said, I think one can also
just fix it in patch 3 or maybe me and Sashiko are just confused.
So since this patch itself is fine and may stay unchanged feel free to
add the below:

Reviewed-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>

Thanks,
Niklas