KVM: Allow userspace to process hypercalls which have no kernel handler

This is useful for paravirtualized graphics devices, for example.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 39cf8fd343a3..de93117f1e97 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1203,7 +1203,16 @@ int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
         }
         switch (nr) {
         default:
-                ;
+                run->hypercall.args[0] = a0;
+                run->hypercall.args[1] = a1;
+                run->hypercall.args[2] = a2;
+                run->hypercall.args[3] = a3;
+                run->hypercall.args[4] = a4;
+                run->hypercall.args[5] = a5;
+                run->hypercall.ret = ret;
+                run->hypercall.longmode = is_long_mode(vcpu);
+                kvm_arch_ops->decache_regs(vcpu);
+                return 0;
         }
         vcpu->regs[VCPU_REGS_RAX] = ret;
         kvm_arch_ops->decache_regs(vcpu);
@@ -1599,6 +1608,13 @@ static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
         vcpu->mmio_needed = 0;
 
+        if (kvm_run->exit_type == KVM_EXIT_TYPE_VM_EXIT
+            && kvm_run->exit_reason == KVM_EXIT_HYPERCALL) {
+                kvm_arch_ops->cache_regs(vcpu);
+                vcpu->regs[VCPU_REGS_RAX] = kvm_run->hypercall.ret;
+                kvm_arch_ops->decache_regs(vcpu);
+        }
+
         r = kvm_arch_ops->run(vcpu, kvm_run);
 
         vcpu_put(vcpu);