[PATCH kernel v4 1/6] PCI: Add a new PCI_BUS_FLAGS_MSI_REMAP flag

[Alexey Kardashevskiy <aik@ozlabs.ru>]

From: Yongji Xie <elohimes@gmail.com>

We introduce a new pci_bus_flags, PCI_BUS_FLAGS_MSI_REMAP
which indicates interrupts of all devices on the bus are
managed by the hardware enabling IRQ remapping (intel naming).
When the capability is enabled, a given PCI device can only
shoot the MSIs assigned for it. In other words, the hardware
can protect system from invalid MSIs of the device by checking
the target address and data when there is something wrong
with MSI part in device or device driver.

The new flag will be set by when the kernel decides that it is safe to
do so. With this flag enabled, we can easily know whether it's safe
to expose MSI-X tables of PCI BARs to userspace. Some usespace
drivers such as VFIO may benefit from this.

Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 include/linux/pci.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8039f9f0ca05..2c6dbb3dd0da 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -200,6 +200,7 @@ enum pci_bus_flags {
 	PCI_BUS_FLAGS_NO_MSI	= (__force pci_bus_flags_t) 1,
 	PCI_BUS_FLAGS_NO_MMRBC	= (__force pci_bus_flags_t) 2,
 	PCI_BUS_FLAGS_NO_AERSID	= (__force pci_bus_flags_t) 4,
+	PCI_BUS_FLAGS_MSI_REMAP = (__force pci_bus_flags_t) 8,
 };
 
 /* These values come from the PCI Express Spec */
-- 
2.11.0