x86/pci: disable MSI(-X) on all devices at shutdown

x86/pci: disable MSI(-X) on all devices at shutdown

Attempt to disable MSI(-X) capabilities on all PCI devices know by Xen at
shutdown.  Doing such disabling should facilitate kexec chained kernel from
booting more reliably, as device MSI(-X) interrupt generation should be
quiesced.

Only attempt to disable MSI(-X) on all devices in the crash context if the
PCI lock is not taken, otherwise the PCI device list could be in an
inconsistent state.  This requires introducing a new pcidevs_trylock()
helper to check whether the lock is currently taken.

Disabling MSI(-X) should prevent "Receive accept error" being raised as a
result of non-disabled interrupts targeting offline CPUs.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 7ab6951981231b4c576a3588248c303001272588
master date: 2025-02-12 15:56:07 +0100