KVM: Emulate hlt on real mode for Intel

This has two use cases: the bios can't boot from disk, and guest smp
bootstrap.

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

3 files changed, 12 insertions, 2 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index ac358b8d3de8..d49b16cae27a 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -347,6 +347,7 @@ struct kvm_vcpu {
                         u32 ar;
                 } tr, es, ds, fs, gs;
         } rmode;
+        int halt_request; /* real mode on Intel only */
 
         int cpuid_nent;
         struct kvm_cpuid_entry cpuid_entries[KVM_MAX_CPUID_ENTRIES];
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 90abd3c58c65..a1f51b9d482d 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1608,8 +1608,13 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
         if (vcpu->rmode.active &&
             handle_rmode_exception(vcpu, intr_info & INTR_INFO_VECTOR_MASK,
-                                                                error_code))
+                                                                error_code)) {
+                if (vcpu->halt_request) {
+                        vcpu->halt_request = 0;
+                        return kvm_emulate_halt(vcpu);
+                }
                 return 1;
+        }
 
         if ((intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK)) == (INTR_TYPE_EXCEPTION | 1)) {
                 kvm_run->exit_reason = KVM_EXIT_DEBUG;
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 6123c0292b22..a4a84817b274 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -143,7 +143,8 @@ static u8 opcode_table[256] = {
         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         /* 0xF0 - 0xF7 */
         0, 0, 0, 0,
-        0, 0, ByteOp | DstMem | SrcNone | ModRM, DstMem | SrcNone | ModRM,
+        ImplicitOps, 0,
+        ByteOp | DstMem | SrcNone | ModRM, DstMem | SrcNone | ModRM,
         /* 0xF8 - 0xFF */
         0, 0, 0, 0,
         0, 0, ByteOp | DstMem | SrcNone | ModRM, DstMem | SrcNone | ModRM
@@ -1149,6 +1150,9 @@ special_insn:
         case 0xae ... 0xaf:     /* scas */
                 DPRINTF("Urk! I don't handle SCAS.\n");
                 goto cannot_emulate;
+        case 0xf4:              /* hlt */
+                ctxt->vcpu->halt_request = 1;
+                goto done;
         }
         goto writeback;