crypto: qat - keep VFs enabled during reset

crypto: qat - keep VFs enabled during reset

When a reset is triggered via sysfs, the PCI core invokes the
reset_prepare() callback while holding pci_dev_lock(), which includes
the PCI configuration space access semaphore. If reset_prepare() calls
adf_dev_down(), the call chain adf_dev_stop() -> adf_disable_sriov()
-> pci_disable_sriov() attempts to acquire the same semaphore,
resulting in a deadlock.

Avoid this by skipping pci_disable_sriov() when ADF_STATUS_RESTARTING
is set. During reset the PCI topology is preserved, so VF devices
remain valid and enumerated across the reset. VF notification and the
quiesce handshake via adf_pf2vf_notify_restarting() are still
performed unconditionally so that VFs stop submitting work before the
PF shuts down.

Correspondingly, skip pci_enable_sriov() in adf_enable_sriov() when
VFs are already present, since their PCI devices were preserved from
before the restart.

This is in preparation for adding reset_prepare() and reset_done()
callbacks in adf_aer.c.

Cc: stable@vger.kernel.org
Signed-off-by: Ahsan Atta <ahsan.atta@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Damian Muszynski <damian.muszynski@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>