Change in coreboot[master]: mb/emulation/qemu: Fix SMP boot

[Patrick Rudolph (Code Review)]

Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/50235 )

Change subject: mb/emulation/qemu: Fix SMP boot
......................................................................

mb/emulation/qemu: Fix SMP boot

Fix booting with SMP enabled, when specifying more CPUs than supported
by the code.

Change-Id: Ib3d7c1a1a7a8633d4d434ccbd46cf92b0074b724
Signed-off-by: Patrick Rudolph 
---
M src/cpu/qemu-x86/Kconfig
M src/mainboard/emulation/qemu-i440fx/northbridge.c
2 files changed, 8 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/35/50235/1

diff --git a/src/cpu/qemu-x86/Kconfig b/src/cpu/qemu-x86/Kconfig
index 641cea8..a22d7f9 100644
--- a/src/cpu/qemu-x86/Kconfig
+++ b/src/cpu/qemu-x86/Kconfig
@@ -44,8 +44,8 @@

config MAX_CPUS
    int
-	default 4 if SMM_ASEG
-	default 32
+	default 32 if SMM_TSEG
+	default 4

config CPU_QEMU_X86_64
    bool "Experimental 64bit support"
diff --git a/src/mainboard/emulation/qemu-i440fx/northbridge.c b/src/mainboard/emulation/qemu-i440fx/northbridge.c
index f49d47da..80fba1d 100644
--- a/src/mainboard/emulation/qemu-i440fx/northbridge.c
+++ b/src/mainboard/emulation/qemu-i440fx/northbridge.c
@@ -271,6 +271,12 @@

if (max_cpus < 0)
    	return;
+	/*
+	 * Do not install more CPUs than supported by coreboot.
+	 * This will cause a buffer overflow where fixed arrays of CONFIG_MAX_CPUS
+	 * are used and might result in a boot failure.
+	 */
+	max_cpus = MIN(max_cpus, CONFIG_MAX_CPUS);

/*
     * TODO: This only handles the simple "qemu -smp $nr" case