On 15/10/14 17:27, Christoffer Dall wrote:
> On Thu, Aug 21, 2014 at 02:06:47PM +0100, Andre Przywara wrote:
>> Currently the maximum number of vCPUs supported is a global value
>> limited by the used GIC model. GICv3 will lift this limit, but we
>> still need to observe it for guests using GICv2.
>> So the maximum number of vCPUs is per-VM value, depending on the
>> GIC model the guest uses.
>> Store and check the value in struct kvm_arch, but keep it down to
>> 8 for now.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> ---
>> arch/arm/include/asm/kvm_host.h | 1 +
>> arch/arm/kvm/arm.c | 6 ++++++
>> arch/arm64/include/asm/kvm_host.h | 3 +++
>> virt/kvm/arm/vgic-v2.c | 5 +++++
>> virt/kvm/arm/vgic-v3.c | 6 ++++++
>> 5 files changed, 21 insertions(+)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index cf99ad0..0638419 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -67,6 +67,7 @@ struct kvm_arch {
>>
>> /* Interrupt controller */
>> struct vgic_dist vgic;
>> + int max_vcpus;
>> };
>>
>> #define KVM_NR_MEM_OBJS 40
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index 157e1b6..190f05f 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -142,6 +142,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>
>> /* Mark the initial VMID generation invalid */
>> kvm->arch.vmid_gen = 0;
>> + kvm->arch.max_vcpus = CONFIG_KVM_ARM_MAX_VCPUS;
>>
>> return ret;
>> out_free_stage2_pgd:
>> @@ -223,6 +224,11 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
>> int err;
>> struct kvm_vcpu *vcpu;
>>
>> + if (id >= kvm->arch.max_vcpus) {
>> + err = -EINVAL;
>> + goto out;
>> + }
>> +
>> vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
>> if (!vcpu) {
>> err = -ENOMEM;
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 017fbae..a325161 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -58,6 +58,9 @@ struct kvm_arch {
>> /* VTTBR value associated with above pgd and vmid */
>> u64 vttbr;
>>
>> + /* The maximum number of vCPUs depends on the used GIC model */
>> + int max_vcpus;
>> +
>> /* Interrupt controller */
>> struct vgic_dist vgic;
>>
>> diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
>> index 90947c6..c7362ff 100644
>> --- a/virt/kvm/arm/vgic-v2.c
>> +++ b/virt/kvm/arm/vgic-v2.c
>> @@ -177,11 +177,16 @@ static struct vgic_params vgic_v2_params;
>> static bool vgic_v2_init_emul(struct kvm *kvm, int type)
>> {
>> struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops;
>> + int nr_vcpus;
>>
>> switch (type) {
>> case KVM_DEV_TYPE_ARM_VGIC_V2:
>> + nr_vcpus = atomic_read(&kvm->online_vcpus);
>> + if (nr_vcpus > 8)
>> + return false;
>> vm_ops->get_lr = vgic_v2_get_lr;
>> vm_ops->set_lr = vgic_v2_set_lr;
>> + kvm->arch.max_vcpus = 8;
>> return true;
>> }
>>
>> diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
>> index a38339e..86e8b99 100644
>> --- a/virt/kvm/arm/vgic-v3.c
>> +++ b/virt/kvm/arm/vgic-v3.c
>> @@ -171,11 +171,17 @@ static const struct vgic_ops vgic_v3_ops = {
>> static bool vgic_v3_init_emul_compat(struct kvm *kvm, int type)
>> {
>> struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops;
>> + int nr_vcpus;
>>
>> switch (type) {
>> case KVM_DEV_TYPE_ARM_VGIC_V2:
>> + nr_vcpus = atomic_read(&kvm->online_vcpus);
>> + if (nr_vcpus > 8)
>> + return false;
>> +
>
> I have a feeling we could be seeing this error a bit, could we dedicate
> an error code for the purpose or print a ratelimited warning or
> something?
Did the latter. To be found in an inbox near you very soon.
Cheers,
Andre.
>
>> vm_ops->get_lr = vgic_v3_get_lr;
>> vm_ops->set_lr = vgic_v3_set_lr;
>> + kvm->arch.max_vcpus = 8;
>> return true;
>> }
>> return false;
>> --
>> 1.7.9.5
>>
> Thanks,
> -Christoffer
>
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