arm64: gic: increase the number of IRQ descriptors

The default value of NR_IRQS is not sufficient to support GICv4.1
features and ~56K LPIs. This parameter would be too small for certain
server platforms where it has many IO devices and is capable of
direct injection of vSGI and vLPI features.

Currently, maximum of 64 + 8192 (IRQ_BITMAP_BITS) IRQ descriptors
are allowed. The vCPU creation fails after reaching count ~400 with
kvm-arm.vgic_v4_enable=1.

This patch increases NR_IRQS to 1^19 to cover 56K LPIs and 262144
vSGIs (16K vPEs x 16).

Reviewed-by: Rohit Khanna <[email protected]>
Reviewed-by: Jason Sequeira <[email protected]>
Signed-off-by: Shanker Donthineni <[email protected]>

arch/arm64/include/asm/irq.h

@@ -4,6 +4,10 @@
 
 #ifndef __ASSEMBLER__
 
+#if defined(CONFIG_ARM_GIC_V3_ITS)
+#define  NR_IRQS  (1 << 19)
+#endif
+
 #include <asm-generic/irq.h>
 
 struct pt_regs;