On Mon, May 16, 2016 at 10:53:34AM +0100, Andre Przywara wrote:
> Userland may want to save and restore the state of the in-kernel VGIC,
> so we provide the code which takes a userland request and translate
> that into calls to our MMIO framework.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> virt/kvm/arm/vgic/vgic-kvm-device.c | 50 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
> index 78621283..c3ec453 100644
> --- a/virt/kvm/arm/vgic/vgic-kvm-device.c
> +++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
> @@ -238,7 +238,55 @@ static int vgic_attr_regs_access(struct kvm_device *dev,
> struct kvm_device_attr *attr,
> u32 *reg, bool is_write)
> {
> - return -ENXIO;
> + gpa_t addr;
> + int cpuid, ret, c;
> + struct kvm_vcpu *vcpu, *tmp_vcpu;
> +
> + cpuid = (attr->attr & KVM_DEV_ARM_VGIC_CPUID_MASK) >>
> + KVM_DEV_ARM_VGIC_CPUID_SHIFT;
> + vcpu = kvm_get_vcpu(dev->kvm, cpuid);
> + addr = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
> +
> + mutex_lock(&dev->kvm->lock);
> +
> + ret = vgic_init(dev->kvm);
> + if (ret)
> + goto out;
> +
> + if (cpuid >= atomic_read(&dev->kvm->online_vcpus)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + /*
> + * Ensure that no other VCPU is running by checking the vcpu->cpu
> + * field. If no other VPCUs are running we can safely access the VGIC
> + * state, because even if another VPU is run after this point, that
> + * VCPU will not touch the vgic state, because it will block on
> + * getting the vgic->lock in kvm_vgic_sync_hwstate().
> + */
We still have a problem here. Want me to write a patch?
-Christoffer
> + kvm_for_each_vcpu(c, tmp_vcpu, dev->kvm) {
> + if (unlikely(tmp_vcpu->cpu != -1)) {
> + ret = -EBUSY;
> + goto out;
> + }
> + }
> +
> + switch (attr->group) {
> + case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
> + ret = -EINVAL;
> + break;
> + case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
> + ret = vgic_v2_dist_uaccess(vcpu, is_write, addr, reg);
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +
> +out:
> + mutex_unlock(&dev->kvm->lock);
> + return ret;
> }
>
> /* V2 ops */
> --
> 2.8.2
>
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