PCI/MSI: Enable and mask MSI-X early
commit 43855395 upstream. The ordering of MSI-X enable in hardware is dysfunctional: 1) MSI-X is disabled in the control register 2) Various setup functions 3) pci_msi_setup_msi_irqs() is invoked which ends up accessing the MSI-X table entries 4) MSI-X is enabled and masked in the control register with the comment that enabling is required for some hardware to access the MSI-X table Step #4 obviously contradicts #3. The history of this is an issue with the NIU hardware. When #4 was introduced the table access actually happened in msix_program_entries() which was invoked after enabling and masking MSI-X. This was changed in commit d71d6432 ("PCI/MSI: Kill redundant call of irq_set_msi_desc() for MSI-X interrupts") which removed the table write from msix_program_entries(). Interestingly enough nobody noticed and either NIU still works or it did not get any testing with a kernel 3.19 or later. Nevertheless this is inconsistent and there is no reason why MSI-X can't be enabled and masked in the control register early on, i.e. move step #4 above to step #1. This preserves the NIU workaround and has no side effects on other hardware. Fixes: d71d6432 ("PCI/MSI: Kill redundant call of irq_set_msi_desc() for MSI-X interrupts") Signed-off-by:Thomas Gleixner <tglx@linutronix.de> Tested-by:
Marc Zyngier <maz@kernel.org> Reviewed-by:
Ashok Raj <ashok.raj@intel.com> Reviewed-by:
Marc Zyngier <maz@kernel.org> Acked-by:
Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210729222542.344136412@linutronix.de Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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2d2c6684
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