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s390/early: improve machine detection

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commit 03aa047ef2 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,
MACHINE_IS_VM, or MACHINE_IS_KVM.

CC: stable@vger.kernel.org
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christian Borntraeger
2018-11-09 09:21:47 +01:00
committed by Greg Kroah-Hartman
parent 04af9475e2
commit bd9759a4a4
2 changed files with 4 additions and 2 deletions
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4
arch/s390/kernel/early.c
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@@ -226,10 +226,10 @@ static noinline __init void detect_machine_type(void)
if (stsi(vmms, 3, 2, 2) || !vmms->count)
return;
/* 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
else if (!memcmp(vmms->vm[0].cpi, "\xa9\x61\xe5\xd4", 4))
S390_lowcore.machine_flags |= MACHINE_FLAG_VM;
}

2
arch/s390/kernel/setup.c
View File

@@ -884,6 +884,8 @@ void __init setup_arch(char **cmdline_p)
pr_info("Linux is running under KVM in 64-bit mode\n");
else if (MACHINE_IS_LPAR)
pr_info("Linux is running natively in 64-bit mode\n");
else
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 */