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 39cf8fd343a3113a8ed9e61b075138dbcf014ab2..de93117f1e971264860258d060c787f63740c50a 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 --git a/include/linux/kvm.h b/include/linux/kvm.h
index c93cf53953afd8e92673f14ffc22930cbe746453..9151ebfa22e99ddf2ceecf990c1b1027772cad8a 100644 (file)
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -11,7 +11,7 @@
 #include <asm/types.h>
 #include <linux/ioctl.h>
 
-#define KVM_API_VERSION 6
+#define KVM_API_VERSION 7
 
 /*
  * Architectural interrupt line count, and the size of the bitmap needed
@@ -41,6 +41,7 @@ enum kvm_exit_reason {
        KVM_EXIT_UNKNOWN          = 0,
        KVM_EXIT_EXCEPTION        = 1,
        KVM_EXIT_IO               = 2,
+       KVM_EXIT_HYPERCALL        = 3,
        KVM_EXIT_DEBUG            = 4,
        KVM_EXIT_HLT              = 5,
        KVM_EXIT_MMIO             = 6,
@@ -103,6 +104,13 @@ struct kvm_run {
                        __u32 len;
                        __u8  is_write;
                } mmio;
+               /* KVM_EXIT_HYPERCALL */
+               struct {
+                       __u64 args[6];
+                       __u64 ret;
+                       __u32 longmode;
+                       __u32 pad;
+               } hypercall;
        };
 };