KVM: arm64: Add vm fd device attribute accessors

A subsequent change will allow userspace to convey a filter for
hypercalls through a vm device attribute. Add the requisite boilerplate
for vm attribute accessors.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230404154050.2270077-4-oliver.upton@linux.dev

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3bd732e..b6e26c0 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1439,11 +1439,28 @@ static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
        }
 }
 
+static int kvm_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+       switch (attr->group) {
+       default:
+               return -ENXIO;
+       }
+}
+
+static int kvm_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
+{
+       switch (attr->group) {
+       default:
+               return -ENXIO;
+       }
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
                       unsigned int ioctl, unsigned long arg)
 {
        struct kvm *kvm = filp->private_data;
        void __user *argp = (void __user *)arg;
+       struct kvm_device_attr attr;
 
        switch (ioctl) {
        case KVM_CREATE_IRQCHIP: {
@@ -1479,6 +1496,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
                        return -EFAULT;
                return kvm_vm_ioctl_mte_copy_tags(kvm, &copy_tags);
        }
+       case KVM_HAS_DEVICE_ATTR: {
+               if (copy_from_user(&attr, argp, sizeof(attr)))
+                       return -EFAULT;
+
+               return kvm_vm_has_attr(kvm, &attr);
+       }
+       case KVM_SET_DEVICE_ATTR: {
+               if (copy_from_user(&attr, argp, sizeof(attr)))
+                       return -EFAULT;
+
+               return kvm_vm_set_attr(kvm, &attr);
+       }
        default:
                return -EINVAL;
        }