PCI/MSI: Prevent MSI hardware interrupt number truncation

BugLink: https://bugs.launchpad.net/bugs/2065721

While calculating the hardware interrupt number for a MSI interrupt, the
higher bits (i.e. from bit-5 onwards a.k.a domain_nr >= 32) of the PCI
domain number gets truncated because of the shifted value casting to return
type of pci_domain_nr() which is 'int'. This for example is resulting in
same hardware interrupt number for devices 0019:00:00.0 and 0039:00:00.0.

To address this cast the PCI domain number to 'irq_hw_number_t' before left
shifting it to calculate the hardware interrupt number.

Please note that this fixes the issue only on 64-bit systems and doesn't
change the behavior for 32-bit systems i.e. the 32-bit systems continue to
have the issue. Since the issue surfaces only if there are too many PCIe
controllers in the system which usually is the case in modern server
systems and they don't tend to run 32-bit kernels.

Fixes: 3878eae ("PCI/MSI: Enhance core to support hierarchy irqdomain")
Signed-off-by: Vidya Sagar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Shanker Donthineni <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
(cherry-picked from commit db744dd)
Signed-off-by: Jamie Nguyen <[email protected]>
Acked-by: Brad Figg <[email protected]>
Acked-by: Jacob Martin <[email protected]>
Acked-by: Noah Wagner <[email protected]>
Signed-off-by: Brad Figg <[email protected]>

drivers/pci/msi/irqdomain.c

@@ -61,7 +61,7 @@ static irq_hw_number_t pci_msi_domain_calc_hwirq(struct msi_desc *desc)
 
 	return (irq_hw_number_t)desc->msi_index |
 		pci_dev_id(dev) << 11 |
-		(pci_domain_nr(dev->bus) & 0xFFFFFFFF) << 27;
+		((irq_hw_number_t)(pci_domain_nr(dev->bus) & 0xFFFFFFFF)) << 27;
 }
 
 static void pci_msi_domain_set_desc(msi_alloc_info_t *arg,