[Xen-devel] [PATCH v11 5/5] x86emul: Raise #UD when emulating an unimplemented instruction.

[Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>]

Modified the behavior of hvm_emulate_one_insn and
vmx_realmode_emulate_one to generate an Invalid Opcode trap when
X86EMUL_UNIMPLEMENTED is returned by the emulator instead of just
crashing the domain.

Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/io.c           |  6 +++++-
 xen/arch/x86/hvm/vmx/realmode.c | 11 ++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 7152c28..a78ab05 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -96,10 +96,14 @@ bool hvm_emulate_one_insn(hvm_emulate_validate_t *validate, 
const char *descr)
     switch ( rc )
     {
     case X86EMUL_UNHANDLEABLE:
-    case X86EMUL_UNIMPLEMENTED:
         hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt, rc);
         return false;
 
+    case X86EMUL_UNIMPLEMENTED:
+        hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt, rc);
+        hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
+        break;
+
     case X86EMUL_EXCEPTION:
         hvm_inject_event(&ctxt.ctxt.event);
         break;
diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c
index c4815ed..dfd5833 100644
--- a/xen/arch/x86/hvm/vmx/realmode.c
+++ b/xen/arch/x86/hvm/vmx/realmode.c
@@ -106,12 +106,21 @@ void vmx_realmode_emulate_one(struct hvm_emulate_ctxt 
*hvmemul_ctxt)
     if ( hvm_vcpu_io_need_completion(vio) || vio->mmio_retry )
         vio->io_completion = HVMIO_realmode_completion;
 
-    if ( rc == X86EMUL_UNHANDLEABLE || rc == X86EMUL_UNIMPLEMENTED )
+    if ( rc == X86EMUL_UNHANDLEABLE )
     {
         gdprintk(XENLOG_ERR, "Failed to emulate insn.\n");
         goto fail;
     }
 
+    if ( rc == X86EMUL_UNIMPLEMENTED )
+    {
+        gdprintk(XENLOG_ERR, "Unimplemented insn.\n");
+        if ( curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE )
+            goto fail;
+
+        realmode_deliver_exception(TRAP_invalid_op, 0, hvmemul_ctxt);
+    }
+
     if ( rc == X86EMUL_EXCEPTION )
     {
         if ( unlikely(curr->domain->debugger_attached) &&
-- 
2.7.4


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