x86/traps: Refactor exc_general_protection()

TDX brings a new exception -- Virtualization Exception (#VE). Handling
of #VE structurally very similar to handling #GP.

Extract two helpers from exc_general_protection() that can be reused for
handling #VE.

No functional changes.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220405232939.73860-7-kirill.shutemov@linux.intel.com

Author: kiryl

arch/x86/kernel/traps.c

@@ -686,13 +686,40 @@ static bool try_fixup_enqcmd_gp(void)
 #endif
 }
 
+static bool gp_try_fixup_and_notify(struct pt_regs *regs, int trapnr,
+				    unsigned long error_code, const char *str)
+{
+	if (fixup_exception(regs, trapnr, error_code, 0))
+		return true;
+
+	current->thread.error_code = error_code;
+	current->thread.trap_nr = trapnr;
+
+	/*
+	 * To be potentially processing a kprobe fault and to trust the result
+	 * from kprobe_running(), we have to be non-preemptible.
+	 */
+	if (!preemptible() && kprobe_running() &&
+	    kprobe_fault_handler(regs, trapnr))
+		return true;
+
+	return notify_die(DIE_GPF, str, regs, error_code, trapnr, SIGSEGV) == NOTIFY_STOP;
+}
+
+static void gp_user_force_sig_segv(struct pt_regs *regs, int trapnr,
+				   unsigned long error_code, const char *str)
+{
+	current->thread.error_code = error_code;
+	current->thread.trap_nr = trapnr;
+	show_signal(current, SIGSEGV, "", str, regs, error_code);
+	force_sig(SIGSEGV);
+}
+
 DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
 {
 	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
 	enum kernel_gp_hint hint = GP_NO_HINT;
-	struct task_struct *tsk;
 	unsigned long gp_addr;
-	int ret;
 
 	if (user_mode(regs) && try_fixup_enqcmd_gp())
 		return;
@@ -711,40 +738,18 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
 		return;
 	}
 
-	tsk = current;
-
 	if (user_mode(regs)) {
 		if (fixup_iopl_exception(regs))
 			goto exit;
 
-		tsk->thread.error_code = error_code;
-		tsk->thread.trap_nr = X86_TRAP_GP;
-
 		if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0))
 			goto exit;
 
-		show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
-		force_sig(SIGSEGV);
+		gp_user_force_sig_segv(regs, X86_TRAP_GP, error_code, desc);
 		goto exit;
 	}
 
-	if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
-		goto exit;
-
-	tsk->thread.error_code = error_code;
-	tsk->thread.trap_nr = X86_TRAP_GP;
-
-	/*
-	 * To be potentially processing a kprobe fault and to trust the result
-	 * from kprobe_running(), we have to be non-preemptible.
-	 */
-	if (!preemptible() &&
-	    kprobe_running() &&
-	    kprobe_fault_handler(regs, X86_TRAP_GP))
-		goto exit;
-
-	ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);
-	if (ret == NOTIFY_STOP)
+	if (gp_try_fixup_and_notify(regs, X86_TRAP_GP, error_code, desc))
 		goto exit;
 
 	if (error_code)