From c7da6fa43cb1c5e649da0f478a491feb9208cae7 Mon Sep 17 00:00:00 2001 From: Pavel Fedin Date: Fri, 18 Dec 2015 14:38:43 +0300 Subject: arm/arm64: KVM: Detect vGIC presence at runtime Before commit 662d9715840aef44dcb573b0f9fab9e8319c868a ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}") is was possible to compile the kernel without vGIC and vTimer support. Commit message says about possibility to detect vGIC support in runtime, but this has never been implemented. This patch introduces runtime check, restoring the lost functionality. It again allows to use KVM on hardware without vGIC. Interrupt controller has to be emulated in userspace in this case. -ENODEV return code from probe function means there's no GIC at all. -ENXIO happens when, for example, there is GIC node in the device tree, but it does not specify vGIC resources. Any other error code is still treated as full stop because it might mean some really serious problems. Signed-off-by: Pavel Fedin Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier --- arch/arm/kvm/arm.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'arch/arm/kvm') diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index f6bcc2e4a133..dda1959f0dde 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -63,6 +63,8 @@ static u32 kvm_next_vmid; static unsigned int kvm_vmid_bits __read_mostly; static DEFINE_SPINLOCK(kvm_vmid_lock); +static bool vgic_present; + static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu) { BUG_ON(preemptible()); @@ -134,7 +136,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.vmid_gen = 0; /* The maximum number of VCPUs is limited by the host's GIC model */ - kvm->arch.max_vcpus = kvm_vgic_get_max_vcpus(); + kvm->arch.max_vcpus = vgic_present ? + kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; return ret; out_free_stage2_pgd: @@ -174,6 +177,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) int r; switch (ext) { case KVM_CAP_IRQCHIP: + r = vgic_present; + break; case KVM_CAP_IOEVENTFD: case KVM_CAP_DEVICE_CTRL: case KVM_CAP_USER_MEMORY: @@ -917,6 +922,8 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, switch (dev_id) { case KVM_ARM_DEVICE_VGIC_V2: + if (!vgic_present) + return -ENXIO; return kvm_vgic_addr(kvm, type, &dev_addr->addr, true); default: return -ENODEV; @@ -931,6 +938,8 @@ long kvm_arch_vm_ioctl(struct file *filp, switch (ioctl) { case KVM_CREATE_IRQCHIP: { + if (!vgic_present) + return -ENXIO; return kvm_vgic_create(kvm, KVM_DEV_TYPE_ARM_VGIC_V2); } case KVM_ARM_SET_DEVICE_ADDR: { @@ -1121,8 +1130,17 @@ static int init_hyp_mode(void) * Init HYP view of VGIC */ err = kvm_vgic_hyp_init(); - if (err) + switch (err) { + case 0: + vgic_present = true; + break; + case -ENODEV: + case -ENXIO: + vgic_present = false; + break; + default: goto out_free_context; + } /* * Init HYP architected timer support -- cgit v1.2.3