Re: [PATCH v3] KVM: Extend MAX_IRQ_ROUTES to 4096 for all archs

[Christian Borntraeger]

On 04/27/2018 02:55 AM, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> 
> Our virtual machines make use of device assignment by configuring
> 12 NVMe disks for high I/O performance. Each NVMe device has 129 
> MSI-X Table entries:
> Capabilities: [50] MSI-X: Enable+ Count=129 Masked-Vector table: BAR=0 offset=00002000
> The windows virtual machines fail to boot since they will map the number of 
> MSI-table entries that the NVMe hardware reported to the bus to msi routing 
> table, this will exceed the 1024. This patch extends MAX_IRQ_ROUTES to 4096
> for all archs, in the future this might be extended again if needed.
> 
> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> Signed-off-by: Tonny Lu <tonnylu@xxxxxxxxxxx>

Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>

> ---
> v2 -> v3:
>  * update comments in the code
> v1 -> v2:
>  * extend MAX_IRQ_ROUTES to 4096 for all archs 
> 
>  include/linux/kvm_host.h | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 6930c63..6d6e79c 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1045,13 +1045,7 @@ static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
>  
>  #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
>  
> -#ifdef CONFIG_S390
> -#define KVM_MAX_IRQ_ROUTES 4096 //FIXME: we can have more than that...
> -#elif defined(CONFIG_ARM64)
> -#define KVM_MAX_IRQ_ROUTES 4096
> -#else
> -#define KVM_MAX_IRQ_ROUTES 1024
> -#endif
> +#define KVM_MAX_IRQ_ROUTES 4096 /* might need extension/rework in the future */
>  
>  bool kvm_arch_can_set_irq_routing(struct kvm *kvm);
>  int kvm_set_irq_routing(struct kvm *kvm,
>