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>

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 39cf8fd..de93117 100644 (file)
--- 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);

diff --cc include/linux/kvm.h
Simple merge