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Commit e0d573a0 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Greg Kroah-Hartman
Browse files

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,
MACHINE_IS_VM, or MACHINE_IS_KVM.

CC: stable@vger.kernel.org
Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b5637644

arch/s390/kernel/early.c

+2 −2
Original line number Diff line number Diff line
@@ -64,10 +64,10 @@ 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;

}

arch/s390/kernel/setup.c

+2 −0
Original line number Diff line number Diff line
@@ -882,6 +882,8 @@ 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 */