2023-01-04 01:58:02

by Shanker Donthineni

Subject: [PATCH] arm64: gic: increase the number of IRQ descriptors

The default value of NR_IRQS is not sufficient to support GICv4.1
features and ~64K 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 64K LPIs and 262144
vSGIs (16K vPEs x 16).

Signed-off-by: Shanker Donthineni <[email protected]>
---
arch/arm64/include/asm/irq.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index 168d710a7b70..741e0e9148ed 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/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>
#include <linux/irqchip/arm-gic-common.h>

--
2.25.1

2023-01-04 02:41:06

by Shanker Donthineni

Subject: Re: [PATCH] arm64: gic: increase the number of IRQ descriptors

Hi,

On 1/3/23 19:22, Shanker Donthineni wrote:
> The default value of NR_IRQS is not sufficient to support GICv4.1
> features and ~64K 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 64K LPIs and 262144
> vSGIs (16K vPEs x 16).

Sorry, created a patch from the wrong kernel branch.
Please review v2 patch.