Re: [PATCH v8 2/4] s390/pci: Reuse FMB buffer and preserve state in device re-enablement

[sashiko-bot@kernel.org]

> Don't free the FMB buffer when disabling measurement in
> zpci_fmb_disable_device(). Instead, make the buffer persistent for the
> lifetime of the device and reuse it across enable/disable cycles. Defer
> freeing the buffer until teardown in zpci_release_device().
> 
> To support the persistent buffers, add the fmb_enabled bool to struct
> zpci_dev to decouple whether FMB is enabled from whether the buffer has
> been allocated. Audit the only consumer of zdev->fmb as a liveness check
> and update it to reflect this change.
> 
> Introduce the function zpci_fmb_reenable_device() to ensure that the FMB
> is enabled. If it was already enabled, disable it, zero the counters,
> and re-enable it. This allows the function to be used in both first-time
> enabling and re-enabling measurement. Call it in zpci_reenable_device()
> to preserve the FMB enablement if it had been implicitly disabled by
> firmware in zpci_disable_device().
> 
> Signed-off-by: Omar Elghoul <oelghoul@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261005154557.57801-1-oelghoul@linux.ibm.com?part=2