Re: [Qemu-devel] [RFC 2/3] intc/arm_gic: Support PPI injection for more than 256 vpus

[Zenghui Yu <yuzenghui@huawei.com>]

Hi Eric,

On 2019/8/28 0:05, Eric Auger wrote:
> Host kernels that expose the KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 capability
> allow injection of PPIs along with vcpu ids larger than 255. Let's
> encode the vpcu id on 12 bits according to the upgraded KVM_IRQ_LINE
> ABI when needed.
> 
> Without that patch qemu exits with "kvm_set_irq: Invalid argument"
> message.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reported-by: Zenghui Yu <yuzenghui@huawei.com>
> ---
>   hw/intc/arm_gic_kvm.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
> index b56fda144f..889293e97f 100644
> --- a/hw/intc/arm_gic_kvm.c
> +++ b/hw/intc/arm_gic_kvm.c
> @@ -56,6 +56,7 @@ void kvm_arm_gic_set_irq(uint32_t num_irq, int irq, int level)
>        * CPU number and interrupt number.
>        */
>       int kvm_irq, irqtype, cpu;
> +    int cpu_idx1 = 0, cpu_idx2 = 0;
>   
>       if (irq < (num_irq - GIC_INTERNAL)) {
>           /* External interrupt. The kernel numbers these like the GIC
> @@ -63,17 +64,20 @@ void kvm_arm_gic_set_irq(uint32_t num_irq, int irq, int level)
>            * internal ones.
>            */
>           irqtype = KVM_ARM_IRQ_TYPE_SPI;
> -        cpu = 0;
>           irq += GIC_INTERNAL;
>       } else {
>           /* Internal interrupt: decode into (cpu, interrupt id) */
>           irqtype = KVM_ARM_IRQ_TYPE_PPI;
>           irq -= (num_irq - GIC_INTERNAL);
>           cpu = irq / GIC_INTERNAL;
> +        cpu_idx2 = cpu / 256;
> +        cpu_idx1 = cpu % 256;
>           irq %= GIC_INTERNAL;
>       }
> -    kvm_irq = (irqtype << KVM_ARM_IRQ_TYPE_SHIFT)
> -        | (cpu << KVM_ARM_IRQ_VCPU_SHIFT) | irq;
> +    kvm_irq = (irqtype << KVM_ARM_IRQ_TYPE_SHIFT) |
> +              (cpu_idx1 << KVM_ARM_IRQ_VCPU_SHIFT) |
> +              ((cpu_idx2 & KVM_ARM_IRQ_VCPU2_MASK) << KVM_ARM_IRQ_VCPU2_SHIFT) |
> +              irq;
>   
>       kvm_set_irq(kvm_state, kvm_irq, !!level);
>   }
> 

For confirmation, should we also adjust the vcpu_index in
arm_cpu_kvm_set_irq(), just like above?


Thanks,
zenghui