vfio/pci: Lock external INTx masking ops

mainline inclusion
from mainline-v6.9-rc1
commit 810cd4bb53456d0503cc4e7934e063835152c1b7
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9E6TS
CVE: CVE-2024-26810

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=810cd4bb53456d0503cc4e7934e063835152c1b7



-------------------------------------------

Mask operations through config space changes to DisINTx may race INTx
configuration changes via ioctl.  Create wrappers that add locking for
paths outside of the core interrupt code.

In particular, irq_type is updated holding igate, therefore testing
is_intx() requires holding igate.  For example clearing DisINTx from
config space can otherwise race changes of the interrupt configuration.

This aligns interfaces which may trigger the INTx eventfd into two
camps, one side serialized by igate and the other only enabled while
INTx is configured.  A subsequent patch introduces synchronization for
the latter flows.

Cc:  <stable@vger.kernel.org>
Fixes: 89e1f7d4 ("vfio: Add PCI device driver")
Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-3-alex.williamson@redhat.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Conflicts:
	drivers/vfio/pci/vfio_pci_intrs.c
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>