x86/hvm: Corrections and improvements to unhandled vmexit logging

* Use gprintk rather than gdprintk.  These logging messages shouldn't
   disappear in release builds, as they usually happen immediately before a
   domain crash.  Raise them from WARNING to ERR.
 * Format the vmexit reason in the same base as is used in the vendor
   manuals (decimal for Intel, hex for AMD), and consistently use 0x for hex
   numbers.
 * Consistently use "Unexpected vmexit" terminology.

In particular, this corrects the information printed for nested VT-x, and
actually prints information for nested SVM.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Release-acked-by: Julien Grall <julien.grall@arm.com>

xen/arch/x86/hvm/svm/nestedsvm.c

@@ -1406,6 +1406,8 @@ nestedsvm_check_intercepts(struct vcpu *v, struct cpu_user_regs *regs,
         /* Always let the guest handle VMMCALL/VMCALL */
         return NESTEDHVM_VMEXIT_INJECT;
     default:
+        gprintk(XENLOG_ERR, "Unexpected nested vmexit: reason %#"PRIx64"\n",
+                exitcode);
         break;
     }
 

xen/arch/x86/hvm/svm/svm.c

@@ -2833,10 +2833,9 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
 
     default:
     unexpected_exit_type:
-        gdprintk(XENLOG_ERR, "unexpected VMEXIT: exit reason = %#"PRIx64", "
-                 "exitinfo1 = %#"PRIx64", exitinfo2 = %#"PRIx64"\n",
-                 exit_reason, 
-                 (u64)vmcb->exitinfo1, (u64)vmcb->exitinfo2);
+        gprintk(XENLOG_ERR, "Unexpected vmexit: reason %#"PRIx64", "
+                "exitinfo1 %#"PRIx64", exitinfo2 %#"PRIx64"\n",
+                exit_reason, vmcb->exitinfo1, vmcb->exitinfo2);
         svm_crash_or_fault(v);
         break;
     }

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

@@ -4106,7 +4106,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
     /* fall through */
     default:
     exit_and_crash:
-        gdprintk(XENLOG_WARNING, "Bad vmexit (reason %#lx)\n", exit_reason);
+        gprintk(XENLOG_ERR, "Unexpected vmexit: reason %lu\n", exit_reason);
 
         if ( vmx_get_cpl() )
             hvm_inject_hw_exception(TRAP_invalid_op,

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

@@ -2550,8 +2550,8 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
             nvcpu->nv_vmexit_pending = 1;
         break;
     default:
-        gdprintk(XENLOG_WARNING, "Unknown nested vmexit reason %x.\n",
-                 exit_reason);
+        gprintk(XENLOG_ERR, "Unexpected nested vmexit: reason %u\n",
+                exit_reason);
     }
 
     return ( nvcpu->nv_vmexit_pending == 1 );