vfio/pci: Disable auto-enable of exclusive INTx IRQ

stable inclusion
from stable-v5.15.154
commit b7a2f0955ffceffadfe098b40b50307431f45438
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9E6TU
CVE: CVE-2024-27437

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b7a2f0955ffceffadfe098b40b50307431f45438



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

[ Upstream commit fe9a7082684eb059b925c535682e68c34d487d43 ]

Currently for devices requiring masking at the irqchip for INTx, ie.
devices without DisINTx support, the IRQ is enabled in request_irq()
and subsequently disabled as necessary to align with the masked status
flag.  This presents a window where the interrupt could fire between
these events, resulting in the IRQ incrementing the disable depth twice.
This would be unrecoverable for a user since the masked flag prevents
nested enables through vfio.

Instead, invert the logic using IRQF_NO_AUTOEN such that exclusive INTx
is never auto-enabled, then unmask as required.

Cc:  <stable@vger.kernel.org>
Fixes: 89e1f7d4 ("vfio: Add PCI device driver")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-2-alex.williamson@redhat.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>