genirq/msi: Silence 'set affinity failed' warning

Various PCI controllers that mux MSIs onto a single IRQ line produce these
"IRQ%d: set affinity failed" warnings when entering suspend. This has been
discussed before [1] [2] and an example test case is included at the end of
this commit message.

Controller drivers that create MSI IRQ domain with
MSI_FLAG_USE_DEF_CHIP_OPS and do not override the .irq_set_affinity()
irqchip callback get assigned the default msi_domain_set_affinity()
callback. That is not desired on controllers where it is not possible to
set affinity of each MSI IRQ line to a specific CPU core due to hardware
limitation.

Introduce flag MSI_FLAG_NO_AFFINITY, which keeps .irq_set_affinity() unset
if the controller driver did not assign it.  This way, migrate_one_irq()
can exit right away, without printing the warning. The .irq_set_affinity()
implementations which only return -EINVAL can be removed from multiple
controller drivers.

  $ grep 25 /proc/interrupts
   25:   0 0 0 0 0 0 0 0   PCIe MSI   0   Edge   PCIe PME

  $ echo core > /sys/power/pm_test ; echo mem > /sys/power/state
  ...
  Disabling non-boot CPUs ...
  IRQ25: set affinity failed(-22). <---------- This is being silenced here
  psci: CPU7 killed (polled 4 ms)
  ...

[1] https://lore.kernel.org/all/[email protected]/
[2] https://lore.kernel.org/all/[email protected]/

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Marek Vasut <[email protected]>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Manivannan Sadhasivam <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>

2 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 944979763825..b10093c4d00e 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -554,6 +554,8 @@ enum {
 	MSI_FLAG_MSIX_CONTIGUOUS	= (1 << 19),
 	/* PCI/MSI-X vectors can be dynamically allocated/freed post MSI-X enable */
 	MSI_FLAG_PCI_MSIX_ALLOC_DYN	= (1 << 20),
+	/* PCI MSIs cannot be steered separately to CPU cores */
+	MSI_FLAG_NO_AFFINITY		= (1 << 21),
 };
 
 /**
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 5fa0547ece0c..ca6e2ae6d6fc 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -832,7 +832,7 @@ static void msi_domain_update_chip_ops(struct msi_domain_info *info)
 	struct irq_chip *chip = info->chip;
 
 	BUG_ON(!chip || !chip->irq_mask || !chip->irq_unmask);
-	if (!chip->irq_set_affinity)
+	if (!chip->irq_set_affinity && !(info->flags & MSI_FLAG_NO_AFFINITY))
 		chip->irq_set_affinity = msi_domain_set_affinity;
 }