KVM: Add support for enabling capabilities per-vcpu

Some times we don't want all capabilities to be available to all
our vcpus. One example for that is the OSI interface, implemented
in the next patch.

In order to have a generic mechanism in how to enable capabilities
individually, this patch introduces a new ioctl that can be used
for this purpose. That way features we don't want in all guests or
userspace configurations can just not be enabled and we're good.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 0bb6a7e826d1..646bfd256e5d 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -150,6 +150,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_PPC_SEGSTATE:
         case KVM_CAP_PPC_PAIRED_SINGLES:
         case KVM_CAP_PPC_UNSET_IRQ:
+        case KVM_CAP_ENABLE_CAP:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
@@ -465,6 +466,23 @@ int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
         return 0;
 }
 
+static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
+                                     struct kvm_enable_cap *cap)
+{
+        int r;
+
+        if (cap->flags)
+                return -EINVAL;
+
+        switch (cap->cap) {
+        default:
+                r = -EINVAL;
+                break;
+        }
+
+        return r;
+}
+
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
                                     struct kvm_mp_state *mp_state)
 {
@@ -493,6 +511,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
                 break;
         }
+        case KVM_ENABLE_CAP:
+        {
+                struct kvm_enable_cap cap;
+                r = -EFAULT;
+                if (copy_from_user(&cap, argp, sizeof(cap)))
+                        goto out;
+                r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
+                break;
+        }
         default:
                 r = -EINVAL;
         }