[PATCH v3 2/9] KVM: arm-vgic: Support KVM_CREATE_DEVICE for VGIC
Marc Zyngier
marc.zyngier at arm.com
Mon Dec 9 10:19:17 EST 2013
On 2013-11-17 04:30, Christoffer Dall wrote:
> Support creating the ARM VGIC device through the KVM_CREATE_DEVICE
> ioctl, which can then later be leveraged to use the
> KVM_{GET/SET}_DEVICE_ATTR, which is useful both for setting addresses
> in
> a more generic API than the ARM-specific one and is useful for
> save/restore of VGIC state.
>
> Adds KVM_CAP_DEVICE_CTRL to ARM capabilities.
>
> Note that we change the check for creating a VGIC from bailing out if
> any VCPUs were created, to bailing out if any VCPUs were ever run.
> This
> is an important distinction that shouldn't break anything, but allows
> creating the VGIC after the VCPUs have been created.
>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
>
> Changelog[v3]:
> - Prevent race in kvm_vgic_create by trying to take all the vcpu
> locks before creating the vgic.
>
> Changelog[v2]:
> - None
> ---
> Documentation/virtual/kvm/devices/arm-vgic.txt | 10 ++++
> arch/arm/kvm/arm.c | 1 +
> include/linux/kvm_host.h | 1 +
> include/uapi/linux/kvm.h | 1 +
> virt/kvm/arm/vgic.c | 58
> +++++++++++++++++++++++-
> virt/kvm/kvm_main.c | 6 ++-
> 6 files changed, 74 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/virtual/kvm/devices/arm-vgic.txt
>
> diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt
> b/Documentation/virtual/kvm/devices/arm-vgic.txt
> new file mode 100644
> index 0000000..38f27f7
> --- /dev/null
> +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
> @@ -0,0 +1,10 @@
> +ARM Virtual Generic Interrupt Controller (VGIC)
> +===============================================
> +
> +Device types supported:
> + KVM_DEV_TYPE_ARM_VGIC_V2 ARM Generic Interrupt Controller v2.0
> +
> +Only one VGIC instance may be instantiated through either this API
> or the
> +legacy KVM_CREATE_IRQCHIP api. The created VGIC will act as the VM
> interrupt
> +controller, requiring emulated user-space devices to inject
> interrupts to the
> +VGIC instead of directly to CPUs.
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index e80b6a1..984908d 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -190,6 +190,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> case KVM_CAP_IRQCHIP:
> r = vgic_present;
> break;
> + case KVM_CAP_DEVICE_CTRL:
> case KVM_CAP_USER_MEMORY:
> case KVM_CAP_SYNC_MMU:
> case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 9523d2a..e68d9db 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1076,6 +1076,7 @@ struct kvm_device *kvm_device_from_filp(struct
> file *filp);
> extern struct kvm_device_ops kvm_mpic_ops;
> extern struct kvm_device_ops kvm_xics_ops;
> extern struct kvm_device_ops kvm_vfio_ops;
> +extern struct kvm_device_ops kvm_arm_vgic_ops;
Can we rename this to kvm_arm_vgic_v2_ops in order to be consistent
with KVM_DEV_TYPE_ARM_VGIC_V2?
>
> #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 902f124..b647c29 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -853,6 +853,7 @@ struct kvm_device_attr {
> #define KVM_DEV_VFIO_GROUP 1
> #define KVM_DEV_VFIO_GROUP_ADD 1
> #define KVM_DEV_VFIO_GROUP_DEL 2
> +#define KVM_DEV_TYPE_ARM_VGIC_V2 5
>
> /*
> * ioctls for VM fds
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 5e9df47..e3fbb5e 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -1433,20 +1433,40 @@ out:
>
> int kvm_vgic_create(struct kvm *kvm)
> {
> - int ret = 0;
> + int i, vcpu_lock_idx = -1, ret = 0;
> + struct kvm_vcpu *vcpu;
>
> mutex_lock(&kvm->lock);
>
> - if (atomic_read(&kvm->online_vcpus) || kvm->arch.vgic.vctrl_base) {
> + if (kvm->arch.vgic.vctrl_base) {
> ret = -EEXIST;
> goto out;
> }
>
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + if (!mutex_trylock(&vcpu->mutex))
> + goto out_unlock;
> + vcpu_lock_idx = i;
> + }
I think this deserves a comment explaining that vcpu->mutex is taken by
vcpu_load...
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + if (vcpu->arch.has_run_once) {
> + ret = -EBUSY;
> + goto out_unlock;
> + }
> + }
> +
> spin_lock_init(&kvm->arch.vgic.lock);
> kvm->arch.vgic.vctrl_base = vgic_vctrl_base;
> kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
> kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
>
> +out_unlock:
> + for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
> + vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
> + mutex_unlock(&vcpu->mutex);
> + }
> +
> out:
> mutex_unlock(&kvm->lock);
> return ret;
> @@ -1510,3 +1530,37 @@ int kvm_vgic_set_addr(struct kvm *kvm,
> unsigned long type, u64 addr)
> mutex_unlock(&kvm->lock);
> return r;
> }
> +
> +static int vgic_set_attr(struct kvm_device *dev, struct
> kvm_device_attr *attr)
> +{
> + return -ENXIO;
> +}
> +
> +static int vgic_get_attr(struct kvm_device *dev, struct
> kvm_device_attr *attr)
> +{
> + return -ENXIO;
> +}
> +
> +static int vgic_has_attr(struct kvm_device *dev, struct
> kvm_device_attr *attr)
> +{
> + return -ENXIO;
> +}
> +
> +static void vgic_destroy(struct kvm_device *dev)
> +{
> + kfree(dev);
> +}
> +
> +static int vgic_create(struct kvm_device *dev, u32 type)
> +{
> + return kvm_vgic_create(dev->kvm);
> +}
> +
> +struct kvm_device_ops kvm_arm_vgic_ops = {
> + .name = "kvm-arm-vgic",
> + .create = vgic_create,
> + .destroy = vgic_destroy,
> + .set_attr = vgic_set_attr,
> + .get_attr = vgic_get_attr,
> + .has_attr = vgic_has_attr,
> +};
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 10015d6..fb8bb21 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2278,7 +2278,11 @@ static int kvm_ioctl_create_device(struct kvm
> *kvm,
> #ifdef CONFIG_KVM_VFIO
> case KVM_DEV_TYPE_VFIO:
> ops = &kvm_vfio_ops;
> - break;
> +#endif
> +#ifdef CONFIG_KVM_ARM_VGIC
> + case KVM_DEV_TYPE_ARM_VGIC_V2:
> + ops = &kvm_arm_vgic_ops;
> + break;
> #endif
> default:
> return -ENODEV;
Otherwise, looks good to me.
M.
--
Fast, cheap, reliable. Pick two.
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