x86emul: Add return code information to error messages

- print the return code of the last failed emulator operation
in hvm_dump_emulation_state.
- print the return code in sh_page_fault (SHADOW_PRINTK) to make the
distiction between X86EMUL_UNHANDLEABLE and X86EMUL_UNIMPLEMENTED.

Signed-off-by: Petre Pircalabu <ppircalabu@bitdefender.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

xen/arch/x86/hvm/emulate.c

@@ -2056,7 +2056,7 @@ int hvm_emulate_one_mmio(unsigned long mfn, unsigned long gla)
     {
     case X86EMUL_UNHANDLEABLE:
     case X86EMUL_UNIMPLEMENTED:
-        hvm_dump_emulation_state(XENLOG_G_WARNING, "MMCFG", &ctxt);
+        hvm_dump_emulation_state(XENLOG_G_WARNING, "MMCFG", &ctxt, rc);
         break;
     case X86EMUL_EXCEPTION:
         hvm_inject_event(&ctxt.ctxt.event);
@@ -2115,7 +2115,7 @@ void hvm_emulate_one_vm_event(enum emul_kind kind, unsigned int trapnr,
         return;
     case X86EMUL_UNIMPLEMENTED:
     case X86EMUL_UNHANDLEABLE:
-        hvm_dump_emulation_state(XENLOG_G_DEBUG, "Mem event", &ctx);
+        hvm_dump_emulation_state(XENLOG_G_DEBUG, "Mem event", &ctx, rc);
         hvm_inject_hw_exception(trapnr, errcode);
         break;
     case X86EMUL_EXCEPTION:
@@ -2243,16 +2243,17 @@ static const char *guest_x86_mode_to_str(int mode)
 }
 
 void hvm_dump_emulation_state(const char *loglvl, const char *prefix,
-                              struct hvm_emulate_ctxt *hvmemul_ctxt)
+                              struct hvm_emulate_ctxt *hvmemul_ctxt, int rc)
 {
     struct vcpu *curr = current;
     const char *mode_str = guest_x86_mode_to_str(hvm_guest_x86_mode(curr));
     const struct segment_register *cs =
         hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt);
 
-    printk("%s%s emulation failed: %pv %s @ %04x:%08lx -> %*ph\n",
-           loglvl, prefix, curr, mode_str, cs->sel, hvmemul_ctxt->insn_buf_eip,
-           hvmemul_ctxt->insn_buf_bytes, hvmemul_ctxt->insn_buf);
+    printk("%s%s emulation failed (%d): %pv %s @ %04x:%08lx -> %*ph\n",
+           loglvl, prefix, rc, curr, mode_str, cs->sel,
+           hvmemul_ctxt->insn_buf_eip, hvmemul_ctxt->insn_buf_bytes,
+           hvmemul_ctxt->insn_buf);
 }
 
 /*

xen/arch/x86/hvm/io.c

@@ -96,11 +96,11 @@ bool hvm_emulate_one_insn(hvm_emulate_validate_t *validate, const char *descr)
     switch ( rc )
     {
     case X86EMUL_UNHANDLEABLE:
-        hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt);
+        hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt, rc);
         return false;
 
     case X86EMUL_UNRECOGNIZED:
-        hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt);
+        hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt, rc);
         hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
         break;
 

xen/arch/x86/hvm/vmx/realmode.c

@@ -147,7 +147,7 @@ void vmx_realmode_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt)
     return;
 
  fail:
-    hvm_dump_emulation_state(XENLOG_G_ERR, "Real-mode", hvmemul_ctxt);
+    hvm_dump_emulation_state(XENLOG_G_ERR, "Real-mode", hvmemul_ctxt, rc);
     domain_crash(curr->domain);
 }
 

xen/arch/x86/mm/shadow/multi.c

@@ -3498,8 +3498,8 @@ static int sh_page_fault(struct vcpu *v,
             v->arch.paging.last_write_emul_ok = 0;
         }
 #endif
-        SHADOW_PRINTK("emulator failure, unshadowing mfn %#lx\n",
-                       mfn_x(gmfn));
+        SHADOW_PRINTK("emulator failure (rc=%d), unshadowing mfn %#lx\n",
+                       r, mfn_x(gmfn));
         /* If this is actually a page table, then we have a bug, and need
          * to support more operations in the emulator.  More likely,
          * though, this is a hint that this page should not be shadowed. */

xen/include/asm-x86/hvm/emulate.h

@@ -92,7 +92,7 @@ int hvmemul_do_pio_buffer(uint16_t port,
                           void *buffer);
 
 void hvm_dump_emulation_state(const char *loglvl, const char *prefix,
-                              struct hvm_emulate_ctxt *hvmemul_ctxt);
+                              struct hvm_emulate_ctxt *hvmemul_ctxt, int rc);
 
 #endif /* __ASM_X86_HVM_EMULATE_H__ */