[tip: irq/urgent] PCI/MSI: Prevent MSI hardware interrupt number truncation

[tip-bot2 for Vidya Sagar]

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     db744ddd59be798c2627efbfc71f707f5a935a40
Gitweb:        https://git.kernel.org/tip/db744ddd59be798c2627efbfc71f707f5a935a40
Author:        Vidya Sagar <vidyas@xxxxxxxxxx>
AuthorDate:    Mon, 15 Jan 2024 19:26:49 +05:30
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 19 Feb 2024 16:11:01 +01:00

PCI/MSI: Prevent MSI hardware interrupt number truncation

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: 3878eaefb89a ("PCI/MSI: Enhance core to support hierarchy irqdomain")
Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20240115135649.708536-1-vidyas@xxxxxxxxxx
---
 drivers/pci/msi/irqdomain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index c8be056..cfd84a8 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/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,