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PCI/MSI: Enable memory decoding before restoring MSI-X messages

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The current MSI-X restoration path assumes the Command register Memory bit
is enabled when writing MSI-X messages. But it's possible the last saved
and restored state of a device may not have the Memory bit enabled, even if
a device driver later enables Memory bit and MSI-X. Attempting to access
Memory space without Memory bit enabled can lead to Unsupported Request
(UR) from the device. Fix this by enabling Memory bit and restore it
afterwards.

Fixes: 41017f0cac ("[PATCH] PCI: MSI(X) save/restore for suspend/resume")
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
[bhelgaas: comment]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260805165518.794-6-alifm@linux.ibm.com
This commit is contained in:
Farhan Ali 2026-08-05 09:55:18 -07:00 committed by Bjorn Helgaas
parent ad05c16b29
commit 231c7a57d1
1 changed files with 10 additions and 0 deletions
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10
drivers/pci/msi/msi.c
View File

@ -870,6 +870,7 @@ void __pci_restore_msix_state(struct pci_dev *dev)
{
struct msi_desc *entry;
bool write_msg;
u16 cmd;
if (!dev->msix_enabled)
return;
@ -879,6 +880,14 @@ void __pci_restore_msix_state(struct pci_dev *dev)
pci_msix_clear_and_set_ctrl(dev, 0,
PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL);
/*
* The restored device state may not have Memory Space enabled.
* Since the MSI-X Table and PBA are in Memory Space, enable it
* while restoring them.
*/
pci_read_config_word(dev, PCI_COMMAND, &cmd);
pci_write_config_word(dev, PCI_COMMAND, cmd | PCI_COMMAND_MEMORY);
write_msg = arch_restore_msi_irqs(dev);
scoped_guard (msi_descs_lock, &dev->dev) {
@ -889,6 +898,7 @@ void __pci_restore_msix_state(struct pci_dev *dev)
}
}
pci_write_config_word(dev, PCI_COMMAND, cmd);
pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
}