Commit 74be2fcd authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Greg Kroah-Hartman

s390/early: improve machine detection

commit 03aa047ef2db4985e444af6ee1c1dd084ad9fb4c upstream.

Right now the early machine detection code check stsi 3.2.2 for "KVM"
and set MACHINE_IS_VM if this is different. As the console detection
uses diagnose 8 if MACHINE_IS_VM returns true this will crash Linux
early for any non z/VM system that sets a different value than KVM.
So instead of assuming z/VM, do not set any of MACHINE_IS_LPAR,

Reviewed-by: default avatarHeiko Carstens <>
Signed-off-by: default avatarChristian Borntraeger <>
Signed-off-by: default avatarMartin Schwidefsky <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent c25a126d
......@@ -224,10 +224,10 @@ static noinline __init void detect_machine_type(void)
if (stsi(vmms, 3, 2, 2) || !vmms->count)
/* Running under KVM? If not we assume z/VM */
/* Detect known hypervisors */
if (!memcmp(vmms->vm[0].cpi, "\xd2\xe5\xd4", 3))
S390_lowcore.machine_flags |= MACHINE_FLAG_KVM;
else if (!memcmp(vmms->vm[0].cpi, "\xa9\x61\xe5\xd4", 4))
S390_lowcore.machine_flags |= MACHINE_FLAG_VM;
......@@ -833,6 +833,8 @@ void __init setup_arch(char **cmdline_p)
pr_info("Linux is running under KVM in 64-bit mode\n");
pr_info("Linux is running natively in 64-bit mode\n");
pr_info("Linux is running as a guest in 64-bit mode\n");
/* Have one command line that is parsed and saved in /proc/cmdline */
/* boot_command_line has been already set up in early.c */
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