[PATCH 02/10] KVM: arm-vgic: Support KVM_CREATE_DEVICE for VGIC
Christoffer Dall
christoffer.dall at linaro.org
Mon Dec 16 12:08:56 EST 2013
On Mon, Dec 16, 2013 at 11:45:21AM +0000, Marc Zyngier wrote:
> On 12/12/13 19:55, 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[v4]:
> > - Rename kvm_arm_vgic_ops to kvm_arm_vgic_v2_ops
> > - Add comment to kvm_vgic_create about locking vcpu->mutex
> >
> > 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 | 63 +++++++++++++++++++++++++-
> > virt/kvm/kvm_main.c | 6 ++-
> > 6 files changed, 79 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 c9fe9d7..cc7c41a 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..521dd76 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_v2_ops;
> >
> > #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..b15d6c1 100644
> > --- a/virt/kvm/arm/vgic.c
> > +++ b/virt/kvm/arm/vgic.c
> > @@ -1433,20 +1433,45 @@ 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;
> > }
> >
> > + /*
> > + * Any time a vcpu is run, vcpu_load is called which tries to grab the
> > + * vcpu->mutex. By grabbing the vcpu->mutex of all VCPUs we ensure
> > + * that no other VCPUs are run while we create the vgic.
> > + */
> > + kvm_for_each_vcpu(i, vcpu, kvm) {
> > + if (!mutex_trylock(&vcpu->mutex))
> > + goto out_unlock;
> > + vcpu_lock_idx = i;
> > + }
> > +
> > + 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 +1535,37 @@ 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_v2_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 a0aa84b..954a0ba 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -2279,7 +2279,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
> > #ifdef CONFIG_KVM_VFIO
> > case KVM_DEV_TYPE_VFIO:
> > ops = &kvm_vfio_ops;
> > - break;
>
> I think you just broke VFIO.
>
Yeah, I'm tired of thinking about VFIO for platform devices so I just
deided to get rid of that stuff ;)
> > +#endif
> > +#ifdef CONFIG_KVM_ARM_VGIC
> > + case KVM_DEV_TYPE_ARM_VGIC_V2:
> > + ops = &kvm_arm_vgic_v2_ops;
> > + break;
>
> Indentation?
>
I have no idea what was in that coffee...
> > #endif
> > default:
> > return -ENODEV;
> >
>
> Provided that you fix the above:
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>
>
Thanks,
--
Christoffer
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