i386/tdx: Wire TDX_REPORT_FATAL_ERROR with GuestPanic facility

Integrate TDX's TDX_REPORT_FATAL_ERROR into QEMU GuestPanic facility

Originated-from: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
Changes in v5:
- mention additional error information in gpa when it presents;
- refine the documentation; (Markus)

Changes in v4:
- refine the documentation; (Markus)

Changes in v3:
- Add docmentation of new type and struct; (Daniel)
- refine the error message handling; (Daniel)

qapi/run-state.json

@@ -483,10 +483,12 @@
 #
 # @s390: s390 guest panic information type (Since: 2.12)
 #
+# @tdx: tdx guest panic information type (Since: 9.0)
+#
 # Since: 2.9
 ##
 { 'enum': 'GuestPanicInformationType',
-  'data': [ 'hyper-v', 's390' ] }
+  'data': [ 'hyper-v', 's390', 'tdx' ] }
 
 ##
 # @GuestPanicInformation:
@@ -501,7 +503,8 @@
  'base': {'type': 'GuestPanicInformationType'},
  'discriminator': 'type',
  'data': {'hyper-v': 'GuestPanicInformationHyperV',
-          's390': 'GuestPanicInformationS390'}}
+          's390': 'GuestPanicInformationS390',
+          'tdx' : 'GuestPanicInformationTdx'}}
 
 ##
 # @GuestPanicInformationHyperV:
@@ -564,6 +567,30 @@
           'psw-addr': 'uint64',
           'reason': 'S390CrashReason'}}
 
+##
+# @GuestPanicInformationTdx:
+#
+# TDX Guest panic information specific to TDX, as specified in the
+# "Guest-Hypervisor Communication Interface (GHCI) Specification",
+# section TDG.VP.VMCALL<ReportFatalError>.
+#
+# @error-code: TD-specific error code
+#
+# @message: Human-readable error message provided by the guest. Not
+#     to be trusted.
+#
+# @gpa: guest-physical address of a page that contains more verbose
+#     error information, as zero-terminated string.  Present when the
+#     "GPA valid" bit (bit 63) is set in @error-code.
+#
+#
+# Since: 9.0
+##
+{'struct': 'GuestPanicInformationTdx',
+ 'data': {'error-code': 'uint64',
+          'message': 'str',
+          '*gpa': 'uint64'}}
+
 ##
 # @MEMORY_FAILURE:
 #

system/runstate.c

@@ -519,6 +519,52 @@ static void qemu_system_wakeup(void)
     }
 }
 
+static char* tdx_parse_panic_message(char *message)
+{
+    bool printable = false;
+    char *buf = NULL;
+    int len = 0, i;
+
+    /*
+     * Although message is defined as a json string, we shouldn't
+     * unconditionally treat it as is because the guest generated it and
+     * it's not necessarily trustable.
+     */
+    if (message) {
+        /* The caller guarantees the NUL-terminated string. */
+        len = strlen(message);
+
+        printable = len > 0;
+        for (i = 0; i < len; i++) {
+            if (!(0x20 <= message[i] && message[i] <= 0x7e)) {
+                printable = false;
+                break;
+            }
+        }
+    }
+
+    if (!printable && len) {
+        /* 3 = length of "%02x " */
+        buf = g_malloc(len * 3);
+        for (i = 0; i < len; i++) {
+            if (message[i] == '\0') {
+                break;
+            } else {
+                sprintf(buf + 3 * i, "%02x ", message[i]);
+            }
+        }
+        if (i > 0)
+            /* replace the last ' '(space) to NUL */
+            buf[i * 3 - 1] = '\0';
+        else
+            buf[0] = '\0';
+
+        return buf;
+    }
+
+    return message;
+}
+
 void qemu_system_guest_panicked(GuestPanicInformation *info)
 {
     qemu_log_mask(LOG_GUEST_ERROR, "Guest crashed");
@@ -560,7 +606,19 @@ void qemu_system_guest_panicked(GuestPanicInformation *info)
                           S390CrashReason_str(info->u.s390.reason),
                           info->u.s390.psw_mask,
                           info->u.s390.psw_addr);
+        } else if (info->type == GUEST_PANIC_INFORMATION_TYPE_TDX) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          " TDX guest reports fatal error:"
+                          " error code: 0x%#" PRIx64 " error message:\"%s\"\n",
+                          info->u.tdx.error_code,
+                          tdx_parse_panic_message(info->u.tdx.message));
+            if (info->u.tdx.error_code & (1ull << 63)) {
+                qemu_log_mask(LOG_GUEST_ERROR, "Additional error information "
+                              "can be found at gpa page: 0x%#" PRIx64 "\n",
+                              info->u.tdx.gpa);
+            }
         }
+
         qapi_free_GuestPanicInformation(info);
     }
 }

target/i386/kvm/tdx.c

@@ -20,6 +20,7 @@
 #include "qom/object_interfaces.h"
 #include "standard-headers/asm-x86/kvm_para.h"
 #include "sysemu/kvm.h"
+#include "sysemu/runstate.h"
 #include "sysemu/sysemu.h"
 #include "exec/ramblock.h"
 
@@ -1092,11 +1093,26 @@ static int tdx_handle_get_quote(X86CPU *cpu, struct kvm_tdx_vmcall *vmcall)
     return 0;
 }
 
+static void tdx_panicked_on_fatal_error(X86CPU *cpu, uint64_t error_code,
+                                        char *message, uint64_t gpa)
+{
+    GuestPanicInformation *panic_info;
+
+    panic_info = g_new0(GuestPanicInformation, 1);
+    panic_info->type = GUEST_PANIC_INFORMATION_TYPE_TDX;
+    panic_info->u.tdx.error_code = error_code;
+    panic_info->u.tdx.message = message;
+    panic_info->u.tdx.gpa = gpa;
+
+    qemu_system_guest_panicked(panic_info);
+}
+
 static int tdx_handle_report_fatal_error(X86CPU *cpu,
                                          struct kvm_tdx_vmcall *vmcall)
 {
     uint64_t error_code = vmcall->in_r12;
     char *message = NULL;
+    uint64_t gpa = -1ull;
 
     if (error_code & 0xffff) {
         error_report("TDX: REPORT_FATAL_ERROR: invalid error code: "
@@ -1125,7 +1141,13 @@ static int tdx_handle_report_fatal_error(X86CPU *cpu,
         assert((char *)tmp == message + GUEST_PANIC_INFO_TDX_MESSAGE_MAX);
     }
 
-    error_report("TD guest reports fatal error. %s\n", message ? : "");
+#define TDX_REPORT_FATAL_ERROR_GPA_VALID    BIT_ULL(63)
+    if (error_code & TDX_REPORT_FATAL_ERROR_GPA_VALID) {
+        gpa = vmcall->in_r13;
+    }
+
+    tdx_panicked_on_fatal_error(cpu, error_code, message, gpa);
+
     return -1;
 }