KVM: Refactor hypercall infrastructure (v3)

This patch refactors the current hypercall infrastructure to better
support live migration and SMP.  It eliminates the hypercall page by
trapping the UD exception that would occur if you used the wrong hypercall
instruction for the underlying architecture and replacing it with the right
one lazily.

A fall-out of this patch is that the unhandled hypercalls no longer trap to
userspace.  There is very little reason though to use a hypercall to
communicate with userspace as PIO or MMIO can be used.  There is no code
in tree that uses userspace hypercalls.

[avi: fix #ud injection on vmx]

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index ced4ac1955db..794d95416f7b 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -476,7 +476,8 @@ static void init_vmcb(struct vmcb *vmcb)
                                         INTERCEPT_DR5_MASK |
                                         INTERCEPT_DR7_MASK;
 
-        control->intercept_exceptions = 1 << PF_VECTOR;
+        control->intercept_exceptions = (1 << PF_VECTOR) |
+                                        (1 << UD_VECTOR);
 
 
         control->intercept =    (1ULL << INTERCEPT_INTR) |
@@ -979,6 +980,17 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
         return 0;
 }
 
+static int ud_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+        int er;
+
+        er = emulate_instruction(&svm->vcpu, kvm_run, 0, 0);
+        if (er != EMULATE_DONE)
+                inject_ud(&svm->vcpu);
+
+        return 1;
+}
+
 static int nm_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 {
         svm->vmcb->control.intercept_exceptions &= ~(1 << NM_VECTOR);
@@ -1045,7 +1057,8 @@ static int vmmcall_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 {
         svm->next_rip = svm->vmcb->save.rip + 3;
         skip_emulated_instruction(&svm->vcpu);
-        return kvm_hypercall(&svm->vcpu, kvm_run);
+        kvm_emulate_hypercall(&svm->vcpu);
+        return 1;
 }
 
 static int invalid_op_interception(struct vcpu_svm *svm,
@@ -1241,6 +1254,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm,
         [SVM_EXIT_WRITE_DR3]                    = emulate_on_interception,
         [SVM_EXIT_WRITE_DR5]                    = emulate_on_interception,
         [SVM_EXIT_WRITE_DR7]                    = emulate_on_interception,
+        [SVM_EXIT_EXCP_BASE + UD_VECTOR]        = ud_interception,
         [SVM_EXIT_EXCP_BASE + PF_VECTOR]        = pf_interception,
         [SVM_EXIT_EXCP_BASE + NM_VECTOR]        = nm_interception,
         [SVM_EXIT_INTR]                         = nop_on_interception,
@@ -1675,7 +1689,6 @@ svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
         hypercall[0] = 0x0f;
         hypercall[1] = 0x01;
         hypercall[2] = 0xd9;
-        hypercall[3] = 0xc3;
 }
 
 static void svm_check_processor_compat(void *rtn)