Alex, On 16/09/16 06:16, Alexander Graf wrote: > While adding the new vgic implementation, apparently nobody tested > the non-vgic path where user space controls the vgic, so two functions > slipped through the cracks that get called in generic code but don't > check whether hardware support is enabled. > > This patch guards them with proper checks to ensure we only try to > use vgic data structures if they are available. Without this, I get > a stack trace: > > [ 74.363037] Unable to handle kernel paging request at virtual address ffffffffffffffe8 > [...] > [ 74.929654] [<ffff000008824bcc>] _raw_spin_lock+0x1c/0x58 > [ 74.935133] [<ffff0000080b7f20>] kvm_vgic_flush_hwstate+0x88/0x288 > [ 74.941406] [<ffff0000080ab0b4>] kvm_arch_vcpu_ioctl_run+0xfc/0x630 > [ 74.947766] [<ffff0000080a15bc>] kvm_vcpu_ioctl+0x2f4/0x710 > [ 74.953420] [<ffff0000082788a8>] do_vfs_ioctl+0xb0/0x728 > [ 74.958807] [<ffff000008278fb4>] SyS_ioctl+0x94/0xa8 > [ 74.963844] [<ffff000008083744>] el0_svc_naked+0x38/0x3c > > Fixes: 0919e84c0 > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Alexander Graf <agraf@xxxxxxx> > --- > virt/kvm/arm/vgic/vgic.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c > index e83b7fe..9f312ba 100644 > --- a/virt/kvm/arm/vgic/vgic.c > +++ b/virt/kvm/arm/vgic/vgic.c > @@ -645,6 +645,9 @@ next: > /* Sync back the hardware VGIC state into our emulation after a guest's run. */ > void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu) > { > + if (!vcpu->kvm->arch.vgic.enabled) > + return; > + > vgic_process_maintenance_interrupt(vcpu); > vgic_fold_lr_state(vcpu); > vgic_prune_ap_list(vcpu); > @@ -653,6 +656,9 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu) > /* Flush our emulation state into the GIC hardware before entering the guest. */ > void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu) > { > + if (!vcpu->kvm->arch.vgic.enabled) > + return; > + > spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock); > vgic_flush_lr_state(vcpu); > spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock); > I hate that fix, because it papers over the fact that we have uninitialized structures all over the shop, and that's not exactly great. How about the following instead: diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index c94b90d..0961128 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -472,6 +472,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) return ret; } + if (unlikely(!irqchip_in_kernel(kvm))) + kvm_no_vgic_init(kvm); + /* * Enable the arch timers only if we have an in-kernel VGIC * and it has been properly initialized, since we cannot handle diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index bb46c03..1b70b1e 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -327,4 +327,6 @@ int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi); */ int kvm_vgic_setup_default_irq_routing(struct kvm *kvm); +void kvm_no_vgic_init(struct kvm *kvm); + #endif /* __KVM_ARM_VGIC_H */ diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c index 83777c1..7b8f12b 100644 --- a/virt/kvm/arm/vgic/vgic-init.c +++ b/virt/kvm/arm/vgic/vgic-init.c @@ -151,9 +151,11 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis) INIT_LIST_HEAD(&dist->lpi_list_head); spin_lock_init(&dist->lpi_list_lock); - dist->spis = kcalloc(nr_spis, sizeof(struct vgic_irq), GFP_KERNEL); - if (!dist->spis) - return -ENOMEM; + if (nr_spis) { + dist->spis = kcalloc(nr_spis, sizeof(struct vgic_irq), GFP_KERNEL); + if (!dist->spis) + return -ENOMEM; + } /* * In the following code we do not take the irq struct lock since @@ -325,6 +327,21 @@ int vgic_lazy_init(struct kvm *kvm) return ret; } +void kvm_no_vgic_init(struct kvm *kvm) +{ + mutex_lock(&kvm->lock); + if (unlikely(!vgic_initialized(kvm))) { + struct kvm_vcpu *vcpu; + int i; + + kvm_vgic_dist_init(kvm, 0); + kvm_for_each_vcpu(i, vcpu, kvm) + kvm_vgic_vcpu_init(vcpu); + kvm->arch.vgic.initialized = true; + } + mutex_unlock(&kvm->lock); +} + /* RESOURCE MAPPING */ /** Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html