x86/irq: Add a Kconfig option for posted MSI

This option will be used to support delivering MSIs as posted
interrupts. Interrupt remapping is required.

Signed-off-by: Jacob Pan <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Jacob Pan

arch/x86/Kconfig

@@ -464,6 +464,17 @@ config X86_X2APIC
 
 	  If you don't know what to do here, say N.
 
+config X86_POSTED_MSI
+	bool "Enable MSI and MSI-x delivery by posted interrupts"
+	depends on X86_64 && IRQ_REMAP
+	help
+	  This enables MSIs that are under interrupt remapping to be delivered as
+	  posted interrupts to the host kernel. Interrupt throughput can
+	  potentially be improved by coalescing CPU notifications during high
+	  frequency bursts.
+
+	  If you don't know what to do here, say N.
+
 config X86_MPPARSE
 	bool "Enable MPS table" if ACPI
 	default y