[RFC PATCH 35/45] KVM: arm/arm64: vgic-new: Add userland access to VGIC dist registers

Andre Przywara
2016-03-25T02:05:18Z

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
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 d9f2383..2e2f8b6 100644
--- a/virt/kvm/arm/vgic/vgic_kvm_device.c
+++ b/virt/kvm/arm/vgic/vgic_kvm_device.c
@@ -264,7 +264,55 @@ 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().
+ */
+ 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_access(vcpu, is_write, addr, 4, reg);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+out:
+ mutex_unlock(&dev->kvm->lock);
+ return ret;
}

/* V2 ops */
--
2.7.3