From fbdeb4af75d022c237ff48cb3021451d7e8c5328 Mon Sep 17 00:00:00 2001
From: Patrick Rudolph <siro@das-labor.org>
Date: Thu, 14 Feb 2019 19:47:03 +0100
Subject: [PATCH] qemu-q35: die if started on wrong machine
MIME-Version: 1.0
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The QEMU machine "PC" doesn't support MCFG.
Die after console init if the user selected the wrong qemu machine
and print a message to use the correct machine type.

Without this patch ramstage dies with non-helpful message:
"get_pbus: dev is NULL!"

Change-Id: I9d1b24176de971c5f827091bc5bc1bac8426f3f6
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31425
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
---
 src/mainboard/emulation/qemu-q35/bootblock.c |  7 +++++++
 src/mainboard/emulation/qemu-q35/romstage.c  | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/mainboard/emulation/qemu-q35/bootblock.c b/src/mainboard/emulation/qemu-q35/bootblock.c
index 13550f7e3d..d5ca7f9ce7 100644
--- a/src/mainboard/emulation/qemu-q35/bootblock.c
+++ b/src/mainboard/emulation/qemu-q35/bootblock.c
@@ -14,6 +14,7 @@
 #include <device/pci_ops.h>
 #include <bootblock_common.h>
 #include <southbridge/intel/i82801ix/i82801ix.h>
+#include <console/console.h>
 
 /* Just define these here, there is no gm35.h file to include. */
 #define D0F0_PCIEXBAR_LO 0x60
@@ -39,6 +40,12 @@ static void bootblock_northbridge_init(void)
 	pci_io_write_config32(PCI_DEV(0,0,0), D0F0_PCIEXBAR_HI, reg);
 	reg = CONFIG_MMCONF_BASE_ADDRESS | 1; /* 256MiB - 0-255 buses. */
 	pci_io_write_config32(PCI_DEV(0,0,0), D0F0_PCIEXBAR_LO, reg);
+
+	/* MCFG is now active. If it's not qemu was started for machine PC */
+	if (CONFIG(BOOTBLOCK_CONSOLE) &&
+	    (pci_read_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_LO) !=
+	     (CONFIG_MMCONF_BASE_ADDRESS | 1)))
+		die("You must run qemu for machine Q35 (-M q35)");
 }
 
 static void enable_spi_prefetch(void)
diff --git a/src/mainboard/emulation/qemu-q35/romstage.c b/src/mainboard/emulation/qemu-q35/romstage.c
index e409ad1e5f..dbaead982a 100644
--- a/src/mainboard/emulation/qemu-q35/romstage.c
+++ b/src/mainboard/emulation/qemu-q35/romstage.c
@@ -22,6 +22,18 @@
 #include <timestamp.h>
 #include <southbridge/intel/i82801ix/i82801ix.h>
 #include <program_loading.h>
+#include <device/pci_ops.h>
+
+#define D0F0_PCIEXBAR_LO 0x60
+
+static void mainboard_machine_check(void)
+{
+	/* Check that MCFG is active. If it's not qemu was started for machine PC */
+	if (!CONFIG(BOOTBLOCK_CONSOLE) &&
+	    (pci_read_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_LO) !=
+	     (CONFIG_MMCONF_BASE_ADDRESS | 1)))
+		die("You must run qemu for machine Q35 (-M q35)");
+}
 
 asmlinkage void car_stage_entry(void)
 {
@@ -29,6 +41,8 @@ asmlinkage void car_stage_entry(void)
 	i82801ix_early_init();
 	console_init();
 
+	mainboard_machine_check();
+
 	cbmem_recovery(0);
 
 	timestamp_add_now(TS_START_ROMSTAGE);